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diff --git a/documentation/mega-manual/mega-manual.html b/documentation/mega-manual/mega-manual.html deleted file mode 100644 index 1b4419f3b9..0000000000 --- a/documentation/mega-manual/mega-manual.html +++ /dev/null @@ -1,12646 +0,0 @@ -<?xml version="1.0" encoding="UTF-8"?> -<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> -<html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title></title><link rel="stylesheet" href="mega-style.css" type="text/css" /><meta name="generator" content="DocBook XSL Stylesheets V1.75.2" /></head><body><div xml:lang="en" class="book" lang="en"><div class="titlepage"><hr /></div> - - <div class="article"><div class="titlepage"><hr /></div><table border="0" summary="manufactured viewport for HTML img" cellspacing="0" cellpadding="0" width="540"><tr style="height: 90px"><td align="right"><img src="figures/yocto-project-transp.png" align="right" width="135" /></td></tr></table><div class="section" title="1. The Yocto Project Quick Start"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="fake-title"></a>1. The Yocto Project Quick Start</h2></div></div></div><p>Copyright © 2010-2012 Linux Foundation</p></div><div class="section" title="2. Welcome!"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="welcome"></a>2. Welcome!</h2></div></div></div><p> - Welcome to the Yocto Project! - The Yocto Project is an open-source collaboration project focused on embedded Linux - developers. - Among other things, the Yocto Project uses a build system based on the Poky project - to construct complete Linux images. - The Poky project, in turn, draws from and contributes back to the OpenEmbedded project. - </p><p> - If you don't have a system that runs Linux and you want to give the Yocto Project a test run, - you might consider using the Yocto Project Build Appliance. - The Build Appliance allows you to build and boot a custom embedded Linux image with the Yocto - Project using a non-Linux development system. - See the <a class="ulink" href="http://www.yoctoproject.org/documentation/build-appliance" target="_top">Yocto - Project Build Appliance</a> for more information. - </p><p> - On the other hand, if you know all about open-source development, Linux development environments, - Git source repositories and the like and you just want some quick information that lets you try out - the Yocto Project on your Linux system, skip right to the - "<a class="link" href="#super-user" title="6. Super User">Super User</a>" section at the end of this quick start. - </p><p> - For the rest of you, this short document will give you some basic information about the environment and - let you experience it in its simplest form. - After reading this document, you will have a basic understanding of what the Yocto Project is - and how to use some of its core components. - This document steps you through a simple example showing you how to build a small image - and run it using the Quick EMUlator (QEMU emulator). - </p><p> - For more detailed information on the Yocto Project, you should check out these resources: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><span class="emphasis"><em>Website:</em></span> The <a class="ulink" href="http://www.yoctoproject.org" target="_top">Yocto Project Website</a> - provides the latest builds, breaking news, full development documentation, and a rich Yocto - Project Development Community into which you can tap. - </p></li><li class="listitem"><p><span class="emphasis"><em>FAQs:</em></span> Lists commonly asked Yocto Project questions and answers. - You can find two FAQs: <a class="ulink" href="https://wiki.yoctoproject.org/wiki/FAQ" target="_top">Yocto Project FAQ</a> on - a wiki, and the - <a class="link" href="#faq" target="_top">FAQ</a> chapter in - the Yocto Project Reference Manual. - </p></li><li class="listitem"><p><span class="emphasis"><em>Developer Screencast:</em></span> The - <a class="ulink" href="http://vimeo.com/36450321" target="_top">Getting Started with the Yocto Project - New - Developer Screencast Tutorial</a> provides a 30-minute video for the user - new to the Yocto Project but familiar with Linux build systems.</p></li></ul></div><p> - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3> - Due to production processes, there could be differences between the Yocto Project - documentation bundled in a released tarball and the - Yocto Project Quick Start on - the <a class="ulink" href="http://www.yoctoproject.org" target="_top">Yocto Project</a> website. - For the latest version of this manual, see the manual on the website. - </div></div><div class="section" title="3. Introducing the Yocto Project Development Environment"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="yp-intro"></a>3. Introducing the Yocto Project Development Environment</h2></div></div></div><p> - The Yocto Project through the OpenEmbedded build system provides an open source development - environment targeting the ARM, MIPS, PowerPC and x86 architectures for a variety of - platforms including x86-64 and emulated ones. - You can use components from the Yocto Project to design, develop, build, debug, simulate, - and test the complete software stack using Linux, the X Window System, GNOME Mobile-based - application frameworks, and Qt frameworks. - </p><div class="mediaobject" align="center"><table border="0" summary="manufactured viewport for HTML img" cellspacing="0" cellpadding="0" width="100%"><tr><td align="center"><img src="figures/yocto-environment.png" align="middle" width="100%" /></td></tr></table><div class="caption"><p>The Yocto Project Development Environment</p></div></div><p> - Here are some highlights for the Yocto Project: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>Provides a recent Linux kernel along with a set of system commands and libraries suitable for the embedded environment.</p></li><li class="listitem"><p>Makes available system components such as X11, Matchbox, GTK+, Pimlico, Clutter, - GuPNP and Qt (among others) so you can create a richer user interface experience on - devices that use displays or have a GUI. - For devices that don't have a GUI or display, you simply would not employ these - components.</p></li><li class="listitem"><p>Creates a focused and stable core compatible with the OpenEmbedded - project with which you can easily and reliably build and develop.</p></li><li class="listitem"><p>Fully supports a wide range of hardware and device emulation through the QEMU - Emulator.</p></li></ul></div><p> - The Yocto Project can generate images for many kinds of devices. - However, the standard example machines target QEMU full-system emulation for x86, x86-64, ARM, MIPS, - and PPC-based architectures as well as specific hardware such as the - <span class="trademark">Intel</span>® Desktop Board DH55TC. - Because an image developed with the Yocto Project can boot inside a QEMU emulator, the - development environment works nicely as a test platform for developing embedded software. - </p><p> - Another important Yocto Project feature is the Sato reference User Interface. - This optional GNOME mobile-based UI, which is intended for devices with - restricted screen sizes, sits neatly on top of a device using the - GNOME Mobile Stack and provides a well-defined user experience. - Implemented in its own layer, it makes it clear to developers how they can implement - their own user interface on top of a Linux image created with the Yocto Project. - </p></div><div class="section" title="4. What You Need and How You Get It"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="yp-resources"></a>4. What You Need and How You Get It</h2></div></div></div><p> - You need these things to develop in the Yocto Project environment: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>A host system running a supported Linux distribution (i.e. recent releases of - Fedora, openSUSE, CentOS, and Ubuntu). - If the host system supports multiple cores and threads, you can configure the - Yocto Project build system to decrease the time needed to build images - significantly. - </p></li><li class="listitem"><p>The right packages.</p></li><li class="listitem"><p>A release of the Yocto Project.</p></li></ul></div><div class="section" title="4.1. The Linux Distribution"><div class="titlepage"><div><div><h3 class="title"><a id="the-linux-distro"></a>4.1. The Linux Distribution</h3></div></div></div><p> - The Yocto Project team is continually verifying more and more Linux - distributions with each release. - In general, if you have the current release minus one of the following - distributions you should have no problems. - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>Ubuntu</p></li><li class="listitem"><p>Fedora</p></li><li class="listitem"><p>openSUSE</p></li><li class="listitem"><p>CentOS</p></li></ul></div><p> - For a list of the distributions under validation and their status, see the - <a class="ulink" href="https://wiki.yoctoproject.org/wiki/Distribution_Support" target="_top">Distribution - Support</a> wiki page. - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3> - For notes about using the Yocto Project on a RHEL 4-based host, see the - <a class="ulink" href="https://wiki.yoctoproject.org/wiki/BuildingOnRHEL4" target="_top">BuildingOnRHEL4</a> - wiki page. - </div><p> - </p><p> - The OpenEmbedded build system should be able to run on any modern distribution with Python 2.6 or 2.7. - Earlier releases of Python are known to not work and the system does not support Python 3 at this time. - This document assumes you are running one of the previously noted distributions on your Linux-based - host systems. - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p> - If you attempt to use a distribution not in the above list, you may or may not have success - you - are venturing into untested territory. - Refer to - <a class="ulink" href="http://www.openembedded.org/index.php?title=OEandYourDistro&action=historysubmit&diff=4309&okdid=4225" target="_top">OE and Your Distro</a> and - <a class="ulink" href="http://www.openembedded.org/index.php?title=Required_software&action=historysubmit&diff=4311&oldid=4251" target="_top">Required Software</a> - for information for other distributions used with the OpenEmbedded project, which might be - a starting point for exploration. - If you go down this path, you should expect problems. - When you do, please go to <a class="ulink" href="http://bugzilla.yoctoproject.org" target="_top">Yocto Project Bugzilla</a> - and submit a bug. - We are interested in hearing about your experience. - </p></div></div><div class="section" title="4.2. The Packages"><div class="titlepage"><div><div><h3 class="title"><a id="packages"></a>4.2. The Packages</h3></div></div></div><p> - Packages and package installation vary depending on your development system. - In general, you need to have root access and then install the required packages. - The next few sections show you how to get set up with the right packages for - Ubuntu, Fedora, openSUSE, and CentOS. - </p><div class="section" title="4.2.1. Ubuntu"><div class="titlepage"><div><div><h4 class="title"><a id="ubuntu"></a>4.2.1. Ubuntu</h4></div></div></div><p> - The packages you need for a supported Ubuntu distribution are shown in the following command: - </p><pre class="literallayout"> - $ sudo apt-get install sed wget subversion git-core coreutils \ - unzip texi2html texinfo libsdl1.2-dev docbook-utils fop gawk \ - python-pysqlite2 diffstat make gcc build-essential xsltproc \ - g++ desktop-file-utils chrpath libgl1-mesa-dev libglu1-mesa-dev \ - autoconf automake groff libtool xterm libxml-parser-perl dblatex - </pre></div><div class="section" title="4.2.2. Fedora"><div class="titlepage"><div><div><h4 class="title"><a id="fedora"></a>4.2.2. Fedora</h4></div></div></div><p> - The packages you need for a supported Fedora distribution are shown in the following - commands: - </p><pre class="literallayout"> - $ sudo yum groupinstall "development tools" - $ sudo yum install python m4 make wget curl ftp tar bzip2 gzip \ - unzip perl texinfo texi2html diffstat openjade \ - docbook-style-dsssl sed docbook-style-xsl docbook-dtds fop libxslt \ - docbook-utils sed bc eglibc-devel ccache pcre pcre-devel quilt \ - groff linuxdoc-tools patch cmake \ - perl-ExtUtils-MakeMaker tcl-devel gettext chrpath ncurses apr \ - SDL-devel mesa-libGL-devel mesa-libGLU-devel gnome-doc-utils \ - autoconf automake libtool xterm dblatex - </pre></div><div class="section" title="4.2.3. openSUSE"><div class="titlepage"><div><div><h4 class="title"><a id="opensuse"></a>4.2.3. openSUSE</h4></div></div></div><p> - The packages you need for a supported openSUSE distribution are shown in the following - command: - </p><pre class="literallayout"> - $ sudo zypper install python gcc gcc-c++ libtool fop \ - subversion git chrpath automake make wget xsltproc \ - diffstat texinfo freeglut-devel libSDL-devel dblatex - </pre></div><div class="section" title="4.2.4. CentOS"><div class="titlepage"><div><div><h4 class="title"><a id="centos"></a>4.2.4. CentOS</h4></div></div></div><p> - The packages you need for a supported CentOS distribution are shown in the following - commands: - </p><pre class="literallayout"> - $ sudo yum -y groupinstall "development tools" - $ sudo yum -y install tetex gawk sqlite-devel vim-common redhat-lsb xz \ - m4 make wget curl ftp tar bzip2 gzip python-devel \ - unzip perl texinfo texi2html diffstat openjade zlib-devel \ - docbook-style-dsssl sed docbook-style-xsl docbook-dtds \ - docbook-utils bc glibc-devel pcre pcre-devel \ - groff linuxdoc-tools patch cmake \ - tcl-devel gettext ncurses apr \ - SDL-devel mesa-libGL-devel mesa-libGLU-devel gnome-doc-utils \ - autoconf automake libtool xterm dblatex - </pre><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p> - Depending on the CentOS version you are using, other requirements and dependencies - might exist. - For details, you should look at the CentOS sections on the - <a class="ulink" href="https://wiki.yoctoproject.org/wiki/Poky/GettingStarted/Dependencies" target="_top">Poky/GettingStarted/Dependencies</a> - wiki page. - </p></div></div></div><div class="section" title="4.3. Yocto Project Release"><div class="titlepage"><div><div><h3 class="title"><a id="releases"></a>4.3. Yocto Project Release</h3></div></div></div><p> - You can download the latest Yocto Project release by going to the - <a class="ulink" href="http://www.yoctoproject.org/download" target="_top">Yocto Project Download page</a>. - Just go to the page and click the "Yocto Downloads" link found in the "Download" - navigation pane to the right to view all available Yocto Project releases. - Then, click the "Yocto Release" link for the release you want from the list to - begin the download. - Nightly and developmental builds are also maintained at - <a class="ulink" href="http://autobuilder.yoctoproject.org/nightly/" target="_top">http://autobuilder.yoctoproject.org/nightly/</a>. - However, for this document a released version of Yocto Project is used. - </p><p> - You can also get the Yocto Project files you need by setting up (cloning in Git terms) - a local copy of the <code class="filename">poky</code> Git repository on your host development - system. - Doing so allows you to contribute back to the Yocto Project project. - For information on how to get set up using this method, see the - "<a class="link" href="#local-yp-release" target="_top">Yocto - Project Release</a>" item in the Yocto Project Development Manual. - </p></div></div><div class="section" title="5. A Quick Test Run"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="test-run"></a>5. A Quick Test Run</h2></div></div></div><p> - Now that you have your system requirements in order, you can give the Yocto Project a try. - This section presents some steps that let you do the following: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>Build an image and run it in the QEMU emulator</p></li><li class="listitem"><p>Use a pre-built image and run it in the QEMU emulator</p></li></ul></div><div class="section" title="5.1. Building an Image"><div class="titlepage"><div><div><h3 class="title"><a id="building-image"></a>5.1. Building an Image</h3></div></div></div><p> - In the development environment you will need to build an image whenever you change hardware - support, add or change system libraries, or add or change services that have dependencies. - </p><div class="mediaobject" align="center"><img src="figures/building-an-image.png" align="middle" /><div class="caption"><p>Building an Image</p></div></div><p> - Use the following commands to build your image. - The OpenEmbedded build process creates an entire Linux distribution, including the toolchain, - from source. - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p> - The build process using Sato currently consumes about 50GB of disk space. - To allow for variations in the build process and for future package expansion, we - recommend having at least 100GB of free disk space. - </p></div><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p> - By default, the build process searches for source code using a pre-determined order - through a set of locations. - If you encounter problems with the build process finding and downloading source code, see the - "<a class="link" href="#how-does-the-yocto-project-obtain-source-code-and-will-it-work-behind-my-firewall-or-proxy-server" target="_top">How does the OpenEmbedded build system obtain source code and will it work behind my - firewall or proxy server?</a>" in the Yocto Project Reference Manual. - </p></div><p> - </p><pre class="literallayout"> - $ wget http://downloads.yoctoproject.org/releases/yocto/yocto-1.3/poky-1.2+snapshot-8.0.tar.bz2 - $ tar xjf poky-1.2+snapshot-8.0.tar.bz2 - $ source poky-1.2+snapshot-8.0/oe-init-build-env poky-1.2+snapshot-8.0-build - </pre><p> - </p><div class="tip" title="Tip" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Tip</h3><p> - To help conserve disk space during builds, you can add the following statement - to your project's configuration file, which for this example - is <code class="filename">poky-1.2+snapshot-8.0-build/conf/local.conf</code>. - Adding this statement deletes the work directory used for building a package - once the package is built. - </p><pre class="literallayout"> - INHERIT += "rm_work" - </pre><p> - </p></div><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>In the previous example, the first command retrieves the Yocto Project - release tarball from the source repositories using the - <code class="filename">wget</code> command. - Alternatively, you can go to the - <a class="ulink" href="http://www.yoctoproject.org/download" target="_top">Yocto Project website's Downloads page</a> - to retrieve the tarball.</p></li><li class="listitem"><p>The second command extracts the files from the tarball and places - them into a directory named <code class="filename">poky-1.2+snapshot-8.0</code> in the current - directory.</p></li><li class="listitem"><p>The third command runs the Yocto Project environment setup script. - Running this script defines OpenEmbedded build environment settings needed to - complete the build. - The script also creates the - <a class="link" href="#build-directory" target="_top">build directory</a>, - which is <code class="filename">poky-1.2+snapshot-8.0-build</code> in this case. - After the script runs, your current working directory is set - to the build directory. - Later, when the build completes, the build directory contains all the files - created during the build. - </p></li></ul></div><p> - Take some time to examine your <code class="filename">local.conf</code> file - in your project's configuration directory. - The defaults in that file should work fine. - However, there are some variables of interest at which you might look. - </p><p> - By default, the target architecture for the build is <code class="filename">qemux86</code>, - which produces an image that can be used in the QEMU emulator and is targeted at an - <span class="trademark">Intel</span>® 32-bit based architecture. - To change this default, edit the value of the <code class="filename">MACHINE</code> variable - in the configuration file before launching the build. - </p><p> - Another couple of variables of interest are the - <a class="link" href="#var-BB_NUMBER_THREADS" target="_top"><code class="filename">BB_NUMBER_THREADS</code></a> and the - <a class="link" href="#var-PARALLEL_MAKE" target="_top"><code class="filename">PARALLEL_MAKE</code></a> variables. - By default, these variables are commented out. - However, if you have a multi-core CPU you might want to uncomment - the lines and set both variables equal to twice the number of your - host's processor cores. - Setting these variables can significantly shorten your build time. - </p><p> - Another consideration before you build is the package manager used when creating - the image. - By default, the OpenEmbedded build system uses the RPM package manager. - You can control this configuration by using the - <code class="filename"><a class="link" href="#var-PACKAGE_CLASSES" target="_top"><code class="filename">PACKAGE_CLASSES</code></a></code> variable. - For additional package manager selection information, see - "<a class="link" href="#ref-classes-package" target="_top">Packaging - <code class="filename">package*.bbclass</code></a>" - in the Yocto Project Reference Manual. - </p><p> - Continue with the following command to build an OS image for the target, which is - <code class="filename">core-image-sato</code> in this example. - For information on the <code class="filename">-k</code> option use the - <code class="filename">bitbake --help</code> command or see the - "<a class="link" href="#usingpoky-components-bitbake" target="_top">BitBake</a>" section in - the Yocto Project Reference Manual. - </p><pre class="literallayout"> - $ bitbake -k core-image-sato - </pre><p> - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p> - BitBake requires Python 2.6 or 2.7. For more information on this requirement, - see the - <a class="link" href="#faq" target="_top">FAQ</a> in the Yocto Project Reference - Manual. - </p></div><p> - The final command runs the image: - </p><pre class="literallayout"> - $ runqemu qemux86 - </pre><p> - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p> - Depending on the number of processors and cores, the amount or RAM, the speed of your - Internet connection and other factors, the build process could take several hours the first - time you run it. - Subsequent builds run much faster since parts of the build are cached. - </p></div><p> - </p></div><div class="section" title="5.2. Using Pre-Built Binaries and QEMU"><div class="titlepage"><div><div><h3 class="title"><a id="using-pre-built"></a>5.2. Using Pre-Built Binaries and QEMU</h3></div></div></div><p> - If hardware, libraries and services are stable, you can get started by using a pre-built binary - of the filesystem image, kernel, and toolchain and run it using the QEMU emulator. - This scenario is useful for developing application software. - </p><div class="mediaobject" align="center"><img src="figures/using-a-pre-built-image.png" align="middle" /><div class="caption"><p>Using a Pre-Built Image</p></div></div><p> - For this scenario, you need to do several things: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>Install the appropriate stand-alone toolchain tarball.</p></li><li class="listitem"><p>Download the pre-built image that will boot with QEMU. - You need to be sure to get the QEMU image that matches your target machine’s - architecture (e.g. x86, ARM, etc.).</p></li><li class="listitem"><p>Download the filesystem image for your target machine's architecture. - </p></li><li class="listitem"><p>Set up the environment to emulate the hardware and then start the QEMU emulator. - </p></li></ul></div><div class="section" title="5.2.1. Installing the Toolchain"><div class="titlepage"><div><div><h4 class="title"><a id="installing-the-toolchain"></a>5.2.1. Installing the Toolchain</h4></div></div></div><p> - You can download a tarball with the pre-built toolchain, which includes the - <code class="filename">runqemu</code> - script and support files, from the appropriate directory under - <a class="ulink" href="http://downloads.yoctoproject.org/releases/yocto/yocto-1.3/toolchain/" target="_top">http://downloads.yoctoproject.org/releases/yocto/yocto-1.3/toolchain/</a>. - Toolchains are available for 32-bit and 64-bit development systems from the - <code class="filename">i686</code> and <code class="filename">x86-64</code> directories, respectively. - Each type of development system supports five target architectures. - The names of the tarballs are such that a string representing the host system appears - first in the filename and then is immediately followed by a string representing - the target architecture. - </p><pre class="literallayout"> - poky-eglibc-<<span class="emphasis"><em>host_system</em></span>>-<<span class="emphasis"><em>arch</em></span>>-toolchain-gmae-<<span class="emphasis"><em>release</em></span>>.tar.bz2 - - Where: - <<span class="emphasis"><em>host_system</em></span>> is a string representing your development system: - i686 or x86_64. - - <<span class="emphasis"><em>arch</em></span>> is a string representing the target architecture: - i586, x86_64, powerpc, mips, or arm. - - <<span class="emphasis"><em>release</em></span>> is the version of Yocto Project. - </pre><p> - For example, the following toolchain tarball is for a 64-bit development - host system and a 32-bit target architecture: - </p><pre class="literallayout"> - poky-eglibc-x86_64-i586-toolchain-gmae-1.3.tar.bz2 - </pre><p> - The toolchain tarballs are self-contained and must be installed into <code class="filename">/opt/poky</code>. - The following commands show how you install the toolchain tarball given a 64-bit development - host system and a 32-bit target architecture. - The example assumes the toolchain tarball is located in <code class="filename">~/toolchains/</code>. - You must have your working directory set to root before unpacking the tarball: - </p><p> - </p><pre class="literallayout"> - $ cd / - $ sudo tar -xvjf ~/toolchains/poky-eglibc-x86_64-i586-toolchain-gmae-1.3.tar.bz2 - </pre><p> - </p><p> - For more information on how to install tarballs, see the - "<a class="link" href="#using-an-existing-toolchain-tarball" target="_top">Using a Cross-Toolchain Tarball</a>" and - "<a class="link" href="#using-the-toolchain-from-within-the-build-tree" target="_top">Using BitBake and the Build Directory</a>" sections in the Yocto Project Application Developer's Guide. - </p></div><div class="section" title="5.2.2. Downloading the Pre-Built Linux Kernel"><div class="titlepage"><div><div><h4 class="title"><a id="downloading-the-pre-built-linux-kernel"></a>5.2.2. Downloading the Pre-Built Linux Kernel</h4></div></div></div><p> - You can download the pre-built Linux kernel suitable for running in the QEMU emulator from - <a class="ulink" href="http://downloads.yoctoproject.org/releases/yocto/yocto-1.3/machines/qemu" target="_top">http://downloads.yoctoproject.org/releases/yocto/yocto-1.3/machines/qemu</a>. - Be sure to use the kernel that matches the architecture you want to simulate. - Download areas exist for the five supported machine architectures: - <code class="filename">qemuarm</code>, <code class="filename">qemumips</code>, <code class="filename">qemuppc</code>, - <code class="filename">qemux86</code>, and <code class="filename">qemux86-64</code>. - </p><p> - Most kernel files have one of the following forms: - </p><pre class="literallayout"> - *zImage-qemu<<span class="emphasis"><em>arch</em></span>>.bin - vmlinux-qemu<<span class="emphasis"><em>arch</em></span>>.bin - - Where: - <<span class="emphasis"><em>arch</em></span>> is a string representing the target architecture: - x86, x86-64, ppc, mips, or arm. - </pre><p> - </p><p> - You can learn more about downloading a Yocto Project kernel in the - "<a class="link" href="#local-kernel-files" target="_top">Yocto Project Kernel</a>" - bulleted item in the Yocto Project Development Manual. - </p></div><div class="section" title="5.2.3. Downloading the Filesystem"><div class="titlepage"><div><div><h4 class="title"><a id="downloading-the-filesystem"></a>5.2.3. Downloading the Filesystem</h4></div></div></div><p> - You can also download the filesystem image suitable for your target architecture from - <a class="ulink" href="http://downloads.yoctoproject.org/releases/yocto/yocto-1.3/machines/qemu" target="_top">http://downloads.yoctoproject.org/releases/yocto/yocto-1.3/machines/qemu</a>. - Again, be sure to use the filesystem that matches the architecture you want - to simulate. - </p><p> - The filesystem image has two tarball forms: <code class="filename">ext3</code> and - <code class="filename">tar</code>. - You must use the <code class="filename">ext3</code> form when booting an image using the - QEMU emulator. - The <code class="filename">tar</code> form can be flattened out in your host development system - and used for build purposes with the Yocto Project. - </p><pre class="literallayout"> - core-image-<<span class="emphasis"><em>profile</em></span>>-qemu<<span class="emphasis"><em>arch</em></span>>.ext3 - core-image-<<span class="emphasis"><em>profile</em></span>>-qemu<<span class="emphasis"><em>arch</em></span>>.tar.bz2 - - Where: - <<span class="emphasis"><em>profile</em></span>> is the filesystem image's profile: - lsb, lsb-dev, lsb-sdk, lsb-qt3, minimal, minimal-dev, sato, sato-dev, or sato-sdk. - For information on these types of image profiles, see the - "<a class="link" href="#ref-images" target="_top">Images</a>" chapter - in the Yocto Project Reference Manual. - - <<span class="emphasis"><em>arch</em></span>> is a string representing the target architecture: - x86, x86-64, ppc, mips, or arm. - </pre><p> - </p></div><div class="section" title="5.2.4. Setting Up the Environment and Starting the QEMU Emulator"><div class="titlepage"><div><div><h4 class="title"><a id="setting-up-the-environment-and-starting-the-qemu-emulator"></a>5.2.4. Setting Up the Environment and Starting the QEMU Emulator</h4></div></div></div><p> - Before you start the QEMU emulator, you need to set up the emulation environment. - The following command form sets up the emulation environment. - </p><pre class="literallayout"> - $ source /opt/poky/1.3/environment-setup-<<span class="emphasis"><em>arch</em></span>>-poky-linux-<<span class="emphasis"><em>if</em></span>> - - Where: - <<span class="emphasis"><em>arch</em></span>> is a string representing the target architecture: - i586, x86_64, ppc603e, mips, or armv5te. - - <<span class="emphasis"><em>if</em></span>> is a string representing an embedded application binary interface. - Not all setup scripts include this string. - </pre><p> - </p><p> - Finally, this command form invokes the QEMU emulator - </p><pre class="literallayout"> - $ runqemu <<span class="emphasis"><em>qemuarch</em></span>> <<span class="emphasis"><em>kernel-image</em></span>> <<span class="emphasis"><em>filesystem-image</em></span>> - - Where: - <<span class="emphasis"><em>qemuarch</em></span>> is a string representing the target architecture: qemux86, qemux86-64, - qemuppc, qemumips, or qemuarm. - - <<span class="emphasis"><em>kernel-image</em></span>> is the architecture-specific kernel image. - - <<span class="emphasis"><em>filesystem-image</em></span>> is the .ext3 filesystem image. - - </pre><p> - </p><p> - Continuing with the example, the following two commands setup the emulation - environment and launch QEMU. - This example assumes the root filesystem (<code class="filename">.ext3</code> file) and - the pre-built kernel image file both reside in your home directory. - The kernel and filesystem are for a 32-bit target architecture. - </p><pre class="literallayout"> - $ cd $HOME - $ source /opt/poky/1.3/environment-setup-i586-poky-linux - $ runqemu qemux86 bzImage-qemux86.bin \ - core-image-sato-qemux86.ext3 - </pre><p> - </p><p> - The environment in which QEMU launches varies depending on the filesystem image and on the - target architecture. - For example, if you source the environment for the ARM target - architecture and then boot the minimal QEMU image, the emulator comes up in a new - shell in command-line mode. - However, if you boot the SDK image, QEMU comes up with a GUI. - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>Booting the PPC image results in QEMU launching in the same shell in - command-line mode.</div><p> - </p></div></div></div><div class="section" title="6. Super User"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="super-user"></a>6. Super User -</h2></div></div></div><p> - This section - <sup>[<a id="id1482592" href="#ftn.id1482592" class="footnote">1</a>]</sup> - gives you a very fast description of how to use the Yocto Project to build images - for a BeagleBoard xM starting from scratch. - The steps were performed on a 64-bit Ubuntu 10.04 system. - </p><div class="section" title="6.1. Getting the Yocto Project"><div class="titlepage"><div><div><h3 class="title"><a id="getting-yocto"></a>6.1. Getting the Yocto Project</h3></div></div></div><p> - Set up your <a class="link" href="#source-directory" target="_top">source directory</a> - one of two ways: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><span class="emphasis"><em>Tarball:</em></span> - Use if you want the latest stable release: - </p><pre class="literallayout"> - $ wget http://downloads.yoctoproject.org/releases/yocto/yocto-1.3/poky-1.2+snapshot-8.0.tar.bz2 - $ tar xvjf poky-1.2+snapshot-8.0.tar.bz2 - </pre></li><li class="listitem"><p><span class="emphasis"><em>Git Repository:</em></span> - Use if you want to work with cutting edge development content: - </p><pre class="literallayout"> - $ git clone git://git.yoctoproject.org/poky - </pre></li></ul></div><p> - The remainder of the section assumes the Git repository method. - </p></div><div class="section" title="6.2. Setting Up Your Host"><div class="titlepage"><div><div><h3 class="title"><a id="setting-up-your-host"></a>6.2. Setting Up Your Host</h3></div></div></div><p> - You need some packages for everything to work. - Rather than duplicate them here, look at the "<a class="link" href="#packages" title="4.2. The Packages">The Packages</a>" - section earlier in this quick start. - </p></div><div class="section" title="6.3. Initializing the Build Environment"><div class="titlepage"><div><div><h3 class="title"><a id="initializing-the-build-environment"></a>6.3. Initializing the Build Environment</h3></div></div></div><p> - From the parent directory of local source directory, initialize your environment - and provide a meaningful - <a class="link" href="#build-directory" target="_top">build directory</a> - name: - </p><pre class="literallayout"> - $ source poky/oe-init-build-env mybuilds - </pre><p> - At this point, the <code class="filename">mybuilds</code> directory has been created for you - and it is now your current working directory. - If you don't provide your own directory name it defaults to <code class="filename">build</code>. - </p></div><div class="section" title="6.4. Configuring the local.conf File"><div class="titlepage"><div><div><h3 class="title"><a id="configuring-the-local.conf-file"></a>6.4. Configuring the local.conf File</h3></div></div></div><p> - Initializing the build environment creates a <code class="filename">conf/local.conf</code> configuration file - in the build directory. - You need to manually edit this file to specify the machine you are building and to optimize - your build time. - Here are the minimal changes to make: - </p><pre class="literallayout"> - BB_NUMBER_THREADS = "8" - PARALLEL_MAKE = "-j 8" - MACHINE ?= "beagleboard" - </pre><p> - Briefly, set <a class="link" href="#var-BB_NUMBER_THREADS" target="_top"><code class="filename">BB_NUMBER_THREADS</code></a> - and <a class="link" href="#var-PARALLEL_MAKE" target="_top"><code class="filename">PARALLEL_MAKE</code></a> to - twice your host processor's number of cores. - </p><p> - A good deal that goes into a Yocto Project build is simply downloading all of the source - tarballs. - Maybe you have been working with another build system (OpenEmbedded, Angstrom, etc) for which - you've built up a sizable directory of source tarballs. - Or perhaps someone else has such a directory for which you have read access. - If so, you can save time by adding the <code class="filename">PREMIRRORS</code> - statement to your configuration file so that local directories are first checked for existing - tarballs before running out to the net: - </p><pre class="literallayout"> - PREMIRRORS_prepend = "\ - git://.*/.* file:///home/you/dl/ \n \ - svn://.*/.* file:///home/you/dl/ \n \ - cvs://.*/.* file:///home/you/dl/ \n \ - ftp://.*/.* file:///home/you/dl/ \n \ - http://.*/.* file:///home/you/dl/ \n \ - https://.*/.* file:///home/you/dl/ \n" - </pre><p> - </p></div><div class="section" title="6.5. Building the Image"><div class="titlepage"><div><div><h3 class="title"><a id="building-the-image"></a>6.5. Building the Image</h3></div></div></div><p> - At this point, you need to select an image to build for the BeagleBoard xM. - If this is your first build using the Yocto Project, you should try the smallest and simplest - image: - </p><pre class="literallayout"> - $ bitbake core-image-minimal - </pre><p> - Now you just wait for the build to finish. - </p><p> - Here are some variations on the build process that could be helpful: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>Fetch all the necessary sources without starting the build: - </p><pre class="literallayout"> - $ bitbake -c fetchall core-image-minimal - </pre><p> - This variation guarantees that you have all the sources for that BitBake target - should you to disconnect from the net and want to do the build later offline. - </p></li><li class="listitem"><p>Specify to continue the build even if BitBake encounters an error. - By default, BitBake aborts the build when it encounters an error. - This command keeps a faulty build going: - </p><pre class="literallayout"> - $ bitbake -k core-image-minimal - </pre></li></ul></div><p> - </p><p> - Once you have your image, you can take steps to load and boot it on the target hardware. - </p></div></div><div class="footnotes"><br /><hr width="100" align="left" /><div class="footnote"><p><sup>[<a id="ftn.id1482592" href="#id1482592" class="para">1</a>] </sup> - Kudos and thanks to Robert P. J. Day of - <a class="ulink" href="http://www.crashcourse.ca" target="_top">CrashCourse</a> for providing the basis - for this "expert" section with information from one of his - <a class="ulink" href="http://www.crashcourse.ca/wiki/index.php/Yocto_Project_Quick_Start" target="_top">wiki</a> - pages. - </p></div></div></div> - -<table border="0" summary="manufactured viewport for HTML img" cellspacing="0" cellpadding="0" width="100%"><tr><td align="left"><img src="figures/dev-title.png" align="left" width="100%" /></td></tr></table> - - <div xml:lang="en" class="book" lang="en"><div class="titlepage"><div><div><h1 class="title"><a id="dev-manual"></a></h1></div><div><div class="authorgroup"> - <div class="author"><h3 class="author"><span class="firstname">Scott</span> <span class="surname">Rifenbark</span></h3><div class="affiliation"> - <span class="orgname">Intel Corporation<br /></span> - </div><code class="email"><<a class="email" href="mailto:scott.m.rifenbark@intel.com">scott.m.rifenbark@intel.com</a>></code></div> - </div></div><div><p class="copyright">Copyright © 2010-2012 Linux Foundation</p></div><div><div class="legalnotice" title="Legal Notice"><a id="id1482939"></a> - <p> - Permission is granted to copy, distribute and/or modify this document under - the terms of the <a class="ulink" href="http://creativecommons.org/licenses/by-sa/2.0/uk/" target="_top"> - Creative Commons Attribution-Share Alike 2.0 UK: England & Wales</a> as published by - Creative Commons. - </p> - - <div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3> - Due to production processes, there could be differences between the Yocto Project - documentation bundled in the release tarball and the - Yocto Project Development Manual on - the <a class="ulink" href="http://www.yoctoproject.org" target="_top">Yocto Project</a> website. - For the latest version of this manual, see the manual on the website. - </div> - </div></div><div><div class="revhistory"><table border="1" width="100%" summary="Revision history"><tr><th align="left" valign="top" colspan="2"><b>Revision History</b></th></tr> - <tr><td align="left">Revision 1.1</td><td align="left">6 October 2011</td></tr><tr><td align="left" colspan="2">The initial document released with the Yocto Project 1.1 Release.</td></tr> - <tr><td align="left">Revision 1.2</td><td align="left">April 2012</td></tr><tr><td align="left" colspan="2">Released with the Yocto Project 1.2 Release.</td></tr> - <tr><td align="left">Revision 1.3</td><td align="left">Sometime in 2012</td></tr><tr><td align="left" colspan="2">Released with the Yocto Project 1.3 Release.</td></tr> - </table></div></div></div><hr /></div> - - - <div class="chapter" title="Chapter 1. The Yocto Project Development Manual"><div class="titlepage"><div><div><h2 class="title"><a id="dev-manual-intro"></a>Chapter 1. The Yocto Project Development Manual</h2></div></div></div><div class="toc"><dl><dt><span class="section"><a href="#intro">1.1. Introduction</a></span></dt><dt><span class="section"><a href="#what-this-manual-provides">1.2. What this Manual Provides</a></span></dt><dt><span class="section"><a href="#what-this-manual-does-not-provide">1.3. What this Manual Does Not Provide</a></span></dt><dt><span class="section"><a href="#other-information">1.4. Other Information</a></span></dt></dl></div><div class="section" title="1.1. Introduction"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="intro"></a>1.1. Introduction</h2></div></div></div><p> - Welcome to the Yocto Project Development Manual! - This manual gives you an idea of how to use the Yocto Project to develop embedded Linux - images and user-space applications to run on targeted devices. - Reading this manual gives you an overview of image, kernel, and user-space application development - using the Yocto Project. - Because much of the information in this manual is general, it contains many references to other - sources where you can find more detail. - For example, detailed information on Git, repositories and open source in general - can be found in many places. - Another example is how to get set up to use the Yocto Project, which our Yocto Project - Quick Start covers. - </p><p> - The Yocto Project Development Manual, however, does provide detailed examples on how to create a - Board Support Package (BSP), change the kernel source code, and reconfigure the kernel. - You can find this information in the appendices of the manual. - </p></div><div class="section" title="1.2. What this Manual Provides"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="what-this-manual-provides"></a>1.2. What this Manual Provides</h2></div></div></div><p> - The following list describes what you can get from this guide: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>Information that lets you get set - up to develop using the Yocto Project.</p></li><li class="listitem"><p>Information to help developers who are new to the open source environment - and to the distributed revision control system Git, which the Yocto Project - uses.</p></li><li class="listitem"><p>An understanding of common end-to-end development models and tasks.</p></li><li class="listitem"><p>Development case overviews for both system development and user-space - applications.</p></li><li class="listitem"><p>An overview and understanding of the emulation environment used with - the Yocto Project (QEMU).</p></li><li class="listitem"><p>An understanding of basic kernel architecture and concepts.</p></li><li class="listitem"><p>Many references to other sources of related information.</p></li></ul></div><p> - </p></div><div class="section" title="1.3. What this Manual Does Not Provide"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="what-this-manual-does-not-provide"></a>1.3. What this Manual Does Not Provide</h2></div></div></div><p> - This manual will not give you the following: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>Step-by-step instructions if those instructions exist in other Yocto - Project documentation. - For example, the Yocto Project Development Manual contains detailed - instruction on how to obtain and configure the - <span class="trademark">Eclipse</span>™ Yocto Plug-in.</p></li><li class="listitem"><p>Reference material. - This type of material resides in an appropriate reference manual. - For example, system variables are documented in the - Yocto Project Reference Manual.</p></li><li class="listitem"><p>Detailed public information that is not specific to the Yocto Project. - For example, exhaustive information on how to use Git is covered better through the - Internet than in this manual.</p></li></ul></div><p> - </p></div><div class="section" title="1.4. Other Information"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="other-information"></a>1.4. Other Information</h2></div></div></div><p> - Because this manual presents overview information for many different topics, you will - need to supplement it with other information. - The following list presents other sources of information you might find helpful: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><span class="emphasis"><em>The <a class="ulink" href="http://www.yoctoproject.org" target="_top">Yocto Project Website</a>: - </em></span> The home page for the Yocto Project provides lots of information on the project - as well as links to software and documentation.</p></li><li class="listitem"><p><span class="emphasis"><em> - Yocto Project Quick Start:</em></span> This short document lets you get started - with the Yocto Project quickly and start building an image.</p></li><li class="listitem"><p><span class="emphasis"><em> - Yocto Project Reference Manual:</em></span> This manual is a reference - guide to the OpenEmbedded build system known as "Poky." - The manual also contains a reference chapter on Board Support Package (BSP) - layout.</p></li><li class="listitem"><p><span class="emphasis"><em> - Yocto Project Application Developer's Guide:</em></span> - This guide provides information that lets you get going with the Application - Development Toolkit (ADT) and stand-alone cross-development toolchains to - develop projects using the Yocto Project.</p></li><li class="listitem"><p><span class="emphasis"><em> - Yocto Project Board Support Package (BSP) Developer's Guide:</em></span> - This guide defines the structure for BSP components. - Having a commonly understood structure encourages standardization.</p></li><li class="listitem"><p><span class="emphasis"><em> - Yocto Project Kernel Architecture and Use Manual:</em></span> - This manual describes the architecture of the Yocto Project kernel and provides - some work flow examples.</p></li><li class="listitem"><p><span class="emphasis"><em> - <a class="ulink" href="http://www.youtube.com/watch?v=3ZlOu-gLsh0" target="_top"> - Eclipse IDE Yocto Plug-in</a>:</em></span> A step-by-step instructional video that - demonstrates how an application developer uses Yocto Plug-in features within - the Eclipse IDE.</p></li><li class="listitem"><p><span class="emphasis"><em> - <a class="ulink" href="https://wiki.yoctoproject.org/wiki/FAQ" target="_top">FAQ</a>:</em></span> - A list of commonly asked questions and their answers.</p></li><li class="listitem"><p><span class="emphasis"><em> - <a class="ulink" href="http://www.yoctoproject.org/download/yocto/yocto-project-1.1-release-notes-poky-8.0" target="_top"> - Release Notes</a>:</em></span> Features, updates and known issues for the current - release of the Yocto Project.</p></li><li class="listitem"><p><span class="emphasis"><em> - <a class="ulink" href="http://www.yoctoproject.org/projects/hob" target="_top"> - Hob</a>:</em></span> A graphical user interface for BitBake. - Hob's primary goal is to enable a user to perform common tasks more easily.</p></li><li class="listitem"><p><span class="emphasis"><em> - <a class="ulink" href="http://www.yoctoproject.org/documentation/build-appliance" target="_top"> - Build Appliance</a>:</em></span> A bootable custom embedded Linux image you can - either build using a non-Linux development system (VMware applications) or download - from the Yocto Project website. - See the <a class="ulink" href="http://www.yoctoproject.org/documentation/build-appliance" target="_top">Build Appliance</a> - page for more information.</p></li><li class="listitem"><p><span class="emphasis"><em> - <a class="ulink" href="http://bugzilla.yoctoproject.org" target="_top">Bugzilla</a>:</em></span> - The bug tracking application the Yocto Project uses. - If you find problems with the Yocto Project, you should report them using this - application.</p></li><li class="listitem"><p><span class="emphasis"><em> - Yocto Project Mailing Lists:</em></span> To subscribe to the Yocto Project mailing - lists, click on the following URLs and follow the instructions: - </p><div class="itemizedlist"><ul class="itemizedlist" type="circle"><li class="listitem"><p><a class="ulink" href="http://lists.yoctoproject.org/listinfo/yocto" target="_top">http://lists.yoctoproject.org/listinfo/yocto</a> for a - Yocto Project Discussions mailing list.</p></li><li class="listitem"><p><a class="ulink" href="http://lists.yoctoproject.org/listinfo/poky" target="_top">http://lists.yoctoproject.org/listinfo/poky</a> for a - Yocto Project Discussions mailing list about the Poky build system.</p></li><li class="listitem"><p><a class="ulink" href="http://lists.yoctoproject.org/listinfo/yocto-announce" target="_top">http://lists.yoctoproject.org/listinfo/yocto-announce</a> - for a mailing list to receive official Yocto Project announcements for developments and - as well as Yocto Project milestones.</p></li></ul></div></li><li class="listitem"><p><span class="emphasis"><em>Internet Relay Chat (IRC):</em></span> - Two IRC channels on freenode are available - for Yocto Project and Poky discussions: <code class="filename">#yocto</code> and - <code class="filename">#poky</code>, respectively.</p></li><li class="listitem"><p><span class="emphasis"><em> - <a class="ulink" href="http://o-hand.com" target="_top">OpenedHand</a>:</em></span> - The company that initially developed the Poky project, which is the basis - for the OpenEmbedded build system used by the Yocto Project. - OpenedHand was acquired by Intel Corporation in 2008.</p></li><li class="listitem"><p><span class="emphasis"><em> - <a class="ulink" href="http://www.intel.com/" target="_top">Intel Corporation</a>:</em></span> - A multinational semiconductor chip manufacturer company whose Software and - Services Group created and supports the Yocto Project. - Intel acquired OpenedHand in 2008.</p></li><li class="listitem"><p><span class="emphasis"><em> - <a class="ulink" href="http://www.openembedded.org" target="_top">OpenEmbedded</a>:</em></span> - The build system used by the Yocto Project. - This project is the upstream, generic, embedded distribution from which the Yocto - Project derives its build system (Poky) from and to which it contributes.</p></li><li class="listitem"><p><span class="emphasis"><em> - <a class="ulink" href="http://developer.berlios.de/projects/bitbake/" target="_top"> - BitBake</a>:</em></span> The tool used by the OpenEmbedded build system - to process project metadata.</p></li><li class="listitem"><p><span class="emphasis"><em> - <a class="ulink" href="http://docs.openembedded.org/bitbake/html/" target="_top"> - BitBake User Manual</a>:</em></span> A comprehensive guide to the BitBake tool. - </p></li><li class="listitem"><p><span class="emphasis"><em> - <a class="ulink" href="http://wiki.qemu.org/Index.html" target="_top">QEMU</a>: - </em></span> An open-source machine emulator and virtualizer.</p></li></ul></div><p> - </p></div></div> - - <div class="chapter" title="Chapter 2. Getting Started with the Yocto Project"><div class="titlepage"><div><div><h2 class="title"><a id="dev-manual-start"></a>Chapter 2. Getting Started with the Yocto Project</h2></div></div></div><div class="toc"><dl><dt><span class="section"><a href="#introducing-the-yocto-project">2.1. Introducing the Yocto Project</a></span></dt><dt><span class="section"><a href="#getting-setup">2.2. Getting Set Up</a></span></dt><dt><span class="section"><a href="#building-images">2.3. Building Images</a></span></dt><dt><span class="section"><a href="#using-pre-built-binaries-and-qemu">2.4. Using Pre-Built Binaries and QEMU</a></span></dt></dl></div><p> - This chapter introduces the Yocto Project and gives you an idea of what you need to get started. - You can find enough information to set up your development host and build or use images for - hardware supported by the Yocto Project by reading the - Yocto Project Quick Start. -</p><p> - The remainder of this chapter summarizes what is in the Yocto Project Quick Start and provides - some higher-level concepts you might want to consider. -</p><div class="section" title="2.1. Introducing the Yocto Project"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="introducing-the-yocto-project"></a>2.1. Introducing the Yocto Project</h2></div></div></div><p> - The Yocto Project is an open-source collaboration project focused on embedded Linux development. - The project currently provides a build system, which is - referred to as the OpenEmbedded build system in the Yocto Project documentation. - The Yocto Project provides various ancillary tools suitable for the embedded developer - and also features the Sato reference User Interface, which is optimized for - stylus driven, low-resolution screens. - </p><p> - You can use the OpenEmbedded build system, which uses - <a class="ulink" href="http://docs.openembedded.org/bitbake/html/" target="_top">BitBake</a>, to develop complete Linux - images and associated user-space applications for architectures based on ARM, MIPS, PowerPC, - x86 and x86-64. - While the Yocto Project does not provide a strict testing framework, - it does provide or generate for you artifacts that let you perform target-level and - emulated testing and debugging. - Additionally, if you are an <span class="trademark">Eclipse</span>™ - IDE user, you can install an Eclipse Yocto Plug-in to allow you to - develop within that familiar environment. - </p></div><div class="section" title="2.2. Getting Set Up"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="getting-setup"></a>2.2. Getting Set Up</h2></div></div></div><p> - Here is what you need to get set up to use the Yocto Project: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><span class="emphasis"><em>Host System:</em></span> You should have a reasonably current - Linux-based host system. - You will have the best results with a recent release of Fedora, - OpenSUSE, Ubuntu, or CentOS as these releases are frequently tested against the Yocto Project - and officially supported. - You should also have about 100 gigabytes of free disk space for building images. - </p></li><li class="listitem"><p><span class="emphasis"><em>Packages:</em></span> The OpenEmbedded build system - requires certain packages exist on your development system (e.g. Python 2.6 or 2.7). - See "<a class="link" href="#packages" target="_top">The Packages</a>" - section in the Yocto Project Quick Start for the exact package - requirements and the installation commands to install them - for the supported distributions.</p></li><li class="listitem"><p><a id="local-yp-release"></a><span class="emphasis"><em>Yocto Project Release:</em></span> - You need a release of the Yocto Project. - You set up a with local <a class="link" href="#source-directory">source directory</a> - one of two ways depending on whether you - are going to contribute back into the Yocto Project or not. - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3> - Regardless of the method you use, this manual refers to the resulting local - hierarchical set of files as the "source directory." - </div><p> - </p><div class="itemizedlist"><ul class="itemizedlist" type="circle"><li class="listitem"><p><span class="emphasis"><em>Tarball Extraction:</em></span> If you are not going to contribute - back into the Yocto Project, you can simply download a Yocto Project release you want - from the website’s <a class="ulink" href="http://www.yoctoproject.org/download" target="_top">download page</a>. - Once you have the tarball, just extract it into a directory of your choice.</p><p>For example, the following command extracts the Yocto Project 1.3 - release tarball - into the current working directory and sets up the local source directory - with a top-level folder named <code class="filename">poky-1.2+snapshot-8.0</code>: - </p><pre class="literallayout"> - $ tar xfj poky-1.2+snapshot-8.0.tar.bz2 - </pre><p>This method does not produce a local Git repository. - Instead, you simply end up with a snapshot of the release.</p></li><li class="listitem"><p><span class="emphasis"><em>Git Repository Method:</em></span> If you are going to be contributing - back into the Yocto Project or you simply want to keep up - with the latest developments, you should use Git commands to set up a local - Git repository of the upstream <code class="filename">poky</code> source repository. - Doing so creates a repository with a complete history of changes and allows - you to easily submit your changes upstream to the project. - Because you cloned the repository, you have access to all the Yocto Project development - branches and tag names used in the upstream repository.</p><p>The following transcript shows how to clone the <code class="filename">poky</code> - Git repository into the current working directory. - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>You can view the Yocto Project Source Repositories at - <a class="ulink" href="http://git.yoctoproject.org/cgit.cgi" target="_top">http://git.yoctoproject.org/cgit.cgi</a></div><p> - The command creates the local repository in a directory named <code class="filename">poky</code>. - For information on Git used within the Yocto Project, see the - "<a class="link" href="#git" title="3.6. Git">Git</a>" section. - </p><pre class="literallayout"> - $ git clone git://git.yoctoproject.org/poky - Initialized empty Git repository in /home/scottrif/poky/.git/ - remote: Counting objects: 141863, done. - remote: Compressing objects: 100% (38624/38624), done. - remote: Total 141863 (delta 99661), reused 141816 (delta 99614) - Receiving objects: 100% (141863/141863), 76.64 MiB | 126 KiB/s, done. - Resolving deltas: 100% (99661/99661), done. - </pre><p>For another example of how to set up your own local Git repositories, see this - <a class="ulink" href="https://wiki.yoctoproject.org/wiki/Transcript:_from_git_checkout_to_meta-intel_BSP" target="_top"> - wiki page</a>, which describes how to create both <code class="filename">poky</code> - and <code class="filename">meta-intel</code> Git repositories.</p></li></ul></div></li><li class="listitem"><p><a id="local-kernel-files"></a><span class="emphasis"><em>Yocto Project Kernel:</em></span> - If you are going to be making modifications to a supported Yocto Project kernel, you - need to establish local copies of the source. - You can find Git repositories of supported Yocto Project Kernels organized under - "Yocto Project Linux Kernel" in the Yocto Project Source Repositories at - <a class="ulink" href="http://git.yoctoproject.org/cgit.cgi" target="_top">http://git.yoctoproject.org/cgit.cgi</a>.</p><p>This setup involves creating a bare clone of the Yocto Project kernel and then - copying that cloned repository. - You can create the bare clone and the copy of the bare clone anywhere you like. - For simplicity, it is recommended that you create these structures outside of the - source directory (usually <code class="filename">poky</code>).</p><p>As an example, the following transcript shows how to create the bare clone - of the <code class="filename">linux-yocto-3.2</code> kernel and then create a copy of - that clone. - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>When you have a local Yocto Project kernel Git repository, you can - reference that repository rather than the upstream Git repository as - part of the <code class="filename">clone</code> command. - Doing so can speed up the process.</div><p>In the following example, the bare clone is named - <code class="filename">linux-yocto-3.2.git</code>, while the - copy is named <code class="filename">my-linux-yocto-3.2-work</code>: - </p><pre class="literallayout"> - $ git clone --bare git://git.yoctoproject.org/linux-yocto-3.2 linux-yocto-3.2.git - Initialized empty Git repository in /home/scottrif/linux-yocto-3.2.git/ - remote: Counting objects: 2468027, done. - remote: Compressing objects: 100% (392255/392255), done. - remote: Total 2468027 (delta 2071693), reused 2448773 (delta 2052498) - Receiving objects: 100% (2468027/2468027), 530.46 MiB | 129 KiB/s, done. - Resolving deltas: 100% (2071693/2071693), done. - </pre><p>Now create a clone of the bare clone just created: - </p><pre class="literallayout"> - $ git clone linux-yocto-3.2.git my-linux-yocto-3.2-work - Initialized empty Git repository in /home/scottrif/my-linux-yocto-3.2-work/.git/ - Checking out files: 100% (37619/37619), done. - </pre></li><li class="listitem"><p><a id="poky-extras-repo"></a><span class="emphasis"><em> - The <code class="filename">poky-extras</code> Git Repository</em></span>: - The <code class="filename">poky-extras</code> Git repository contains metadata needed - only if you are modifying and building the kernel image. - In particular, it contains the kernel BitBake append (<code class="filename">.bbappend</code>) - files that you - edit to point to your locally modified kernel source files and to build the kernel - image. - Pointing to these local files is much more efficient than requiring a download of the - kernel's source files from upstream each time you make changes to the kernel.</p><p>You can find the <code class="filename">poky-extras</code> Git Repository in the - "Yocto Metadata Layers" area of the Yocto Project Source Repositories at - <a class="ulink" href="http://git.yoctoproject.org/cgit.cgi" target="_top">http://git.yoctoproject.org/cgit.cgi</a>. - It is good practice to create this Git repository inside the source directory.</p><p>Following is an example that creates the <code class="filename">poky-extras</code> Git - repository inside the source directory, which is named <code class="filename">poky</code> - in this case: - </p><pre class="literallayout"> - $ git clone git://git.yoctoproject.org/poky-extras poky-extras - Initialized empty Git repository in /home/scottrif/poky/poky-extras/.git/ - remote: Counting objects: 618, done. - remote: Compressing objects: 100% (558/558), done. - remote: Total 618 (delta 192), reused 307 (delta 39) - Receiving objects: 100% (618/618), 526.26 KiB | 111 KiB/s, done. - Resolving deltas: 100% (192/192), done. - </pre></li><li class="listitem"><p><a id="supported-board-support-packages-(bsps)"></a><span class="emphasis"><em>Supported Board - Support Packages (BSPs):</em></span> - The Yocto Project provides a layer called <code class="filename">meta-intel</code> and - it is maintained in its own separate Git repository. - The <code class="filename">meta-intel</code> layer contains many supported - <a class="link" href="#bsp-layers" target="_top">BSP Layers</a>.</p><p>Similar considerations exist for setting up the <code class="filename">meta-intel</code> - layer. - You can get set up for BSP development one of two ways: tarball extraction or - with a local Git repository. - It is a good idea to use the same method that you used to set up the source directory. - Regardless of the method you use, the Yocto Project uses the following BSP layer - naming scheme: - </p><pre class="literallayout"> - meta-<BSP_name> - </pre><p> - where <BSP_name> is the recognized BSP name. - Here are some examples: - </p><pre class="literallayout"> - meta-crownbay - meta-emenlow - meta-n450 - </pre><p> - See the - "<a class="link" href="#bsp-layers" target="_top">BSP Layers</a>" - section in the Yocto Project Board Support Package (BSP) Developer's Guide for more - information on BSP Layers. - </p><div class="itemizedlist"><ul class="itemizedlist" type="circle"><li class="listitem"><p><span class="emphasis"><em>Tarball Extraction:</em></span> You can download any released - BSP tarball from the same - <a class="ulink" href="http://www.yoctoproject.org/download" target="_top">download site</a> used - to get the Yocto Project release. - Once you have the tarball, just extract it into a directory of your choice. - Again, this method just produces a snapshot of the BSP layer in the form - of a hierarchical directory structure.</p></li><li class="listitem"><p><span class="emphasis"><em>Git Repository Method:</em></span> If you are working - with a local Git repository for your source directory, you should also use this method - to set up the <code class="filename">meta-intel</code> Git repository. - You can locate the <code class="filename">meta-intel</code> Git repository in the - "Yocto Metadata Layers" area of the Yocto Project Source Repositories at - <a class="ulink" href="http://git.yoctoproject.org/cgit.cgi" target="_top">http://git.yoctoproject.org/cgit.cgi</a>.</p><p>Typically, you set up the <code class="filename">meta-intel</code> Git repository inside - the source directory. - For example, the following transcript shows the steps to clone the - <code class="filename">meta-intel</code> - Git repository inside the local <code class="filename">poky</code> Git repository. - </p><pre class="literallayout"> - $ git clone git://git.yoctoproject.org/meta-intel.git - Initialized empty Git repository in /home/scottrif/poky/meta-intel/.git/ - remote: Counting objects: 3380, done. - remote: Compressing objects: 100% (2750/2750), done. - remote: Total 3380 (delta 1689), reused 227 (delta 113) - Receiving objects: 100% (3380/3380), 1.77 MiB | 128 KiB/s, done. - Resolving deltas: 100% (1689/1689), done. - </pre><p>The same - <a class="ulink" href="https://wiki.yoctoproject.org/wiki/Transcript:_from_git_checkout_to_meta-intel_BSP" target="_top"> - wiki page</a> referenced earlier covers how to - set up the <code class="filename">meta-intel</code> Git repository.</p></li></ul></div></li><li class="listitem"><p><span class="emphasis"><em>Eclipse Yocto Plug-in:</em></span> If you are developing - applications using the Eclipse Integrated Development Environment (IDE), - you will need this plug-in. - See the - "<a class="link" href="#setting-up-the-eclipse-ide" title="5.2.2.1. Setting Up the Eclipse IDE">Setting up the Eclipse IDE</a>" - section for more information.</p></li></ul></div><p> - </p></div><div class="section" title="2.3. Building Images"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="building-images"></a>2.3. Building Images</h2></div></div></div><p> - The build process creates an entire Linux distribution, including the toolchain, from source. - For more information on this topic, see the - "<a class="link" href="#building-image" target="_top">Building an Image</a>" - section in the Yocto Project Quick Start. - </p><p> - The build process is as follows: - </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Make sure you have set up the source directory described in the - previous section.</p></li><li class="listitem"><p>Initialize the build environment by sourcing a build environment - script.</p></li><li class="listitem"><p>Optionally ensure the <code class="filename">conf/local.conf</code> configuration file, - which is found in the - <a class="link" href="#build-directory">build directory</a>, - is set up how you want it. - This file defines many aspects of the build environment including - the target machine architecture through the - <code class="filename"><a class="link" href="#var-MACHINE" target="_top">MACHINE</a></code> variable, - the development machine's processor use through the - <code class="filename"><a class="link" href="#var-BB_NUMBER_THREADS" target="_top">BB_NUMBER_THREADS</a></code> and - <code class="filename"><a class="link" href="#var-PARALLEL_MAKE" target="_top">PARALLEL_MAKE</a></code> variables, and - a centralized tarball download directory through the - <code class="filename"><a class="link" href="#var-DL_DIR" target="_top">DL_DIR</a></code> variable.</p></li><li class="listitem"><p>Build the image using the <code class="filename">bitbake</code> command. - If you want information on BitBake, see the user manual at - <a class="ulink" href="http://docs.openembedded.org/bitbake/html" target="_top">http://docs.openembedded.org/bitbake/html</a>.</p></li><li class="listitem"><p>Run the image either on the actual hardware or using the QEMU - emulator.</p></li></ol></div><p> - </p></div><div class="section" title="2.4. Using Pre-Built Binaries and QEMU"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="using-pre-built-binaries-and-qemu"></a>2.4. Using Pre-Built Binaries and QEMU</h2></div></div></div><p> - Another option you have to get started is to use pre-built binaries. - The Yocto Project provides many types of binaries with each release. - See the <a class="link" href="#ref-images" target="_top">Images</a> - chapter in the Yocto Project Reference Manual - for descriptions of the types of binaries that ship with a Yocto Project - release. - </p><p> - Using a pre-built binary is ideal for developing software applications to run on your - target hardware. - To do this, you need to be able to access the appropriate cross-toolchain tarball for - the architecture on which you are developing. - If you are using an SDK type image, the image ships with the complete toolchain native to - the architecture. - If you are not using an SDK type image, you need to separately download and - install the stand-alone Yocto Project cross-toolchain tarball. - </p><p> - Regardless of the type of image you are using, you need to download the pre-built kernel - that you will boot in the QEMU emulator and then download and extract the target root - filesystem for your target machine’s architecture. - You can get architecture-specific binaries and filesystem from - <a class="ulink" href="http://downloads.yoctoproject.org/releases/yocto/yocto-1.3/machines" target="_top">machines</a>. - You can get stand-alone toolchains from - <a class="ulink" href="http://downloads.yoctoproject.org/releases/yocto/yocto-1.3/toolchain/" target="_top">toolchains</a>. - Once you have all your files, you set up the environment to emulate the hardware - by sourcing an environment setup script. - Finally, you start the QEMU emulator. - You can find details on all these steps in the - "<a class="link" href="#using-pre-built" target="_top">Using Pre-Built Binaries and QEMU</a>" - section of the Yocto Project Quick Start. - </p><p> - Using QEMU to emulate your hardware can result in speed issues - depending on the target and host architecture mix. - For example, using the <code class="filename">qemux86</code> image in the emulator - on an Intel-based 32-bit (x86) host machine is fast because the target and - host architectures match. - On the other hand, using the <code class="filename">qemuarm</code> image on the same Intel-based - host can be slower. - But, you still achieve faithful emulation of ARM-specific issues. - </p><p> - To speed things up, the QEMU images support using <code class="filename">distcc</code> - to call a cross-compiler outside the emulated system. - If you used <code class="filename">runqemu</code> to start QEMU, and the - <code class="filename">distccd</code> application is present on the host system, any - BitBake cross-compiling toolchain available from the build system is automatically - used from within QEMU simply by calling <code class="filename">distcc</code>. - You can accomplish this by defining the cross-compiler variable - (e.g. <code class="filename">export CC="distcc"</code>). - Alternatively, if you are using a suitable SDK image or the appropriate - stand-alone toolchain is present in <code class="filename">/opt/poky</code>, - the toolchain is also automatically used. - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3> - Several mechanisms exist that let you connect to the system running on the - QEMU emulator: - <div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>QEMU provides a framebuffer interface that makes standard - consoles available.</p></li><li class="listitem"><p>Generally, headless embedded devices have a serial port. - If so, you can configure the operating system of the running image - to use that port to run a console. - The connection uses standard IP networking.</p></li><li class="listitem"><p>SSH servers exist in some QEMU images. - The <code class="filename">core-image-sato</code> QEMU image has a Dropbear secure - shell (ssh) server that runs with the root password disabled. - The <code class="filename">core-image-basic</code> and <code class="filename">core-image-lsb</code> QEMU images - have OpenSSH instead of Dropbear. - Including these SSH servers allow you to use standard <code class="filename">ssh</code> and - <code class="filename">scp</code> commands. - The <code class="filename">core-image-minimal</code> QEMU image, however, contains no ssh - server.</p></li><li class="listitem"><p>You can use a provided, user-space NFS server to boot the QEMU session - using a local copy of the root filesystem on the host. - In order to make this connection, you must extract a root filesystem tarball by using the - <code class="filename">runqemu-extract-sdk</code> command. - After running the command, you must then point the <code class="filename">runqemu</code> - script to the extracted directory instead of a root filesystem image file.</p></li></ul></div></div></div></div> - - <div class="chapter" title="Chapter 3. The Yocto Project Open Source Development Environment"><div class="titlepage"><div><div><h2 class="title"><a id="dev-manual-newbie"></a>Chapter 3. The Yocto Project Open Source Development Environment</h2></div></div></div><div class="toc"><dl><dt><span class="section"><a href="#open-source-philosophy">3.1. Open Source Philosophy</a></span></dt><dt><span class="section"><a href="#usingpoky-changes-collaborate">3.2. Using the Yocto Project in a Team Environment</a></span></dt><dt><span class="section"><a href="#yocto-project-repositories">3.3. Yocto Project Source Repositories</a></span></dt><dt><span class="section"><a href="#yocto-project-terms">3.4. Yocto Project Terms</a></span></dt><dt><span class="section"><a href="#licensing">3.5. Licensing</a></span></dt><dt><span class="section"><a href="#git">3.6. Git</a></span></dt><dd><dl><dt><span class="section"><a href="#repositories-tags-and-branches">3.6.1. Repositories, Tags, and Branches</a></span></dt><dt><span class="section"><a href="#basic-commands">3.6.2. Basic Commands</a></span></dt></dl></dd><dt><span class="section"><a href="#workflows">3.7. Workflows</a></span></dt><dt><span class="section"><a href="#tracking-bugs">3.8. Tracking Bugs</a></span></dt><dt><span class="section"><a href="#how-to-submit-a-change">3.9. How to Submit a Change</a></span></dt><dd><dl><dt><span class="section"><a href="#pushing-a-change-upstream">3.9.1. Using Scripts to Push a Change Upstream and Request a Pull</a></span></dt><dt><span class="section"><a href="#submitting-a-patch">3.9.2. Using Email to Submit a Patch</a></span></dt></dl></dd></dl></div><p> - This chapter helps you understand the Yocto Project as an open source development project. - In general, working in an open source environment is very different from working in a - closed, proprietary environment. - Additionally, the Yocto Project uses specific tools and constructs as part of its development - environment. - This chapter specifically addresses open source philosophy, licensing issues, code repositories, - the open source distributed version control system Git, and best practices using the Yocto Project. -</p><div class="section" title="3.1. Open Source Philosophy"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="open-source-philosophy"></a>3.1. Open Source Philosophy</h2></div></div></div><p> - Open source philosophy is characterized by software development directed by peer production - and collaboration through an active community of developers. - Contrast this to the more standard centralized development models used by commercial software - companies where a finite set of developers produces a product for sale using a defined set - of procedures that ultimately result in an end product whose architecture and source material - are closed to the public. - </p><p> - Open source projects conceptually have differing concurrent agendas, approaches, and production. - These facets of the development process can come from anyone in the public (community) that has a - stake in the software project. - The open source environment contains new copyright, licensing, domain, and consumer issues - that differ from the more traditional development environment. - In an open source environment, the end product, source material, and documentation are - all available to the public at no cost. - </p><p> - A benchmark example of an open source project is the Linux Kernel, which was initially conceived - and created by Finnish computer science student Linus Torvalds in 1991. - Conversely, a good example of a non-open source project is the - <span class="trademark">Windows</span>® family of operating - systems developed by <span class="trademark">Microsoft</span>® Corporation. - </p><p> - Wikipedia has a good historical description of the Open Source Philosophy - <a class="ulink" href="http://en.wikipedia.org/wiki/Open_source" target="_top">here</a>. - You can also find helpful information on how to participate in the Linux Community - <a class="ulink" href="http://ldn.linuxfoundation.org/book/how-participate-linux-community" target="_top">here</a>. - </p></div><div class="section" title="3.2. Using the Yocto Project in a Team Environment"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="usingpoky-changes-collaborate"></a>3.2. Using the Yocto Project in a Team Environment</h2></div></div></div><p> - It might not be immediately clear how you can use the Yocto Project in a team environment, - or scale it for a large team of developers. - The specifics of any situation determine the best solution. - Granted that the Yocto Project offers immense flexibility regarding this, practices do exist - that experience has shown work well. - </p><p> - The core component of any development effort with the Yocto Project is often an - automated build and testing framework along with an image generation process. - You can use these core components to check that the metadata can be built, - highlight when commits break the build, and provide up-to-date images that - allow developers to test the end result and use it as a base platform for further - development. - Experience shows that buildbot is a good fit for this role. - What works well is to configure buildbot to make two types of builds: - incremental and full (from scratch). - See <a class="ulink" href="http://autobuilder.yoctoproject.org:8010/" target="_top">the buildbot for the - Yocto Project</a> for an example implementation that uses buildbot. - </p><p> - You can tie incremental builds to a commit hook that triggers the build - each time a commit is made to the metadata. - This practice results in useful acid tests that determine whether a given commit - breaks the build in some serious way. - Associating a build to a commit can catch a lot of simple errors. - Furthermore, the tests are fast so developers can get quick feedback on changes. - </p><p> - Full builds build and test everything from the ground up. - These types of builds usually happen at predetermined times like during the - night when the machine load is low. - </p><p> - Most teams have many pieces of software undergoing active development at any given time. - You can derive large benefits by putting these pieces under the control of a source - control system that is compatible (i.e. Git or Subversion (SVN)) with the OpenEmbeded - build system that the Yocto Project uses. - You can then set the autobuilder to pull the latest revisions of the packages - and test the latest commits by the builds. - This practice quickly highlights issues. - The build system easily supports testing configurations that use both a - stable known good revision and a floating revision. - The build system can also take just the changes from specific source control branches. - This capability allows you to track and test specific changes. - </p><p> - Perhaps the hardest part of setting this up is defining the software project or - the metadata policies that surround the different source control systems. - Of course circumstances will be different in each case. - However, this situation reveals one of the Yocto Project's advantages - - the system itself does not - force any particular policy on users, unlike a lot of build systems. - The system allows the best policies to be chosen for the given circumstances. - </p></div><div class="section" title="3.3. Yocto Project Source Repositories"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="yocto-project-repositories"></a>3.3. Yocto Project Source Repositories</h2></div></div></div><p> - The Yocto Project team maintains complete source repositories for all Yocto Project files - at <a class="ulink" href="http://git.yoctoproject.org/cgit/cgit.cgi" target="_top">http://git.yoctoproject.org/cgit/cgit.cgi</a>. - This web-based source code browser is organized into categories by function such as - IDE Plugins, Matchbox, Poky, Yocto Linux Kernel, and so forth. - From the interface, you can click on any particular item in the "Name" column and - see the URL at the bottom of the page that you need to set up a Git repository for - that particular item. - Having a local Git repository of the source directory (poky) allows you to - make changes, contribute to the history, and ultimately enhance the Yocto Project's - tools, Board Support Packages, and so forth. - </p><p> - Conversely, if you are a developer that is not interested in contributing back to the - Yocto Project, you have the ability to simply download and extract release tarballs - and use them within the Yocto Project environment. - All that is required is a particular release of the Yocto Project and - your application source code. - </p><p> - For any supported release of Yocto Project, you can go to the Yocto Project website’s - <a class="ulink" href="http://www.yoctoproject.org/download" target="_top">download page</a> and get a - tarball of the release. - You can also go to this site to download any supported BSP tarballs. - Unpacking the tarball gives you a hierarchical source directory that lets you develop - using the Yocto Project. - </p><p> - Once you are set up through either tarball extraction or creation of Git repositories, - you are ready to develop. - </p><p> - In summary, here is where you can get the project files needed for development: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><a id="source-repositories"></a><span class="emphasis"><em><a class="ulink" href="http://git.yoctoproject.org/cgit/cgit.cgi" target="_top">Source Repositories:</a></em></span> - This area contains IDE Plugins, Matchbox, Poky, Poky Support, Tools, Yocto Linux Kernel, and Yocto - Metadata Layers. - You can create local copies of Git repositories for each of these areas.</p><p> - </p><table border="0" summary="manufactured viewport for HTML img" cellspacing="0" cellpadding="0" width="540"><tr style="height: 360px"><td align="center"><img src="figures/source-repos.png" align="middle" width="540" /></td></tr></table><p> - </p></li><li class="listitem"><p><a id="index-downloads"></a><span class="emphasis"><em><a class="ulink" href="http://downloads.yoctoproject.org/releases/" target="_top">Index of /releases:</a></em></span> - This area contains index releases such as - the <span class="trademark">Eclipse</span>™ - Yocto Plug-in, miscellaneous support, poky, pseudo, cross-development toolchains, - and all released versions of Yocto Project in the form of images or tarballs. - Downloading and extracting these files does not produce a local copy of the - Git repository but rather a snapshot of a particular release or image.</p><p> - </p><table border="0" summary="manufactured viewport for HTML img" cellspacing="0" cellpadding="0" width="540"><tr style="height: 360px"><td align="center"><img src="figures/index-downloads.png" align="middle" width="540" /></td></tr></table><p> - </p></li><li class="listitem"><p><span class="emphasis"><em><a class="ulink" href="http://www.yoctoproject.org/download" target="_top">Yocto Project Download Page</a></em></span> - This page on the Yocto Project website allows you to download any Yocto Project - release or Board Support Package (BSP) in tarball form. - The tarballs are similar to those found in the - <a class="ulink" href="http://downloads.yoctoproject.org/releases/" target="_top">Index of /releases:</a> area.</p><p> - </p><table border="0" summary="manufactured viewport for HTML img" cellspacing="0" cellpadding="0" width="540"><tr style="height: 360px"><td align="center"><img src="figures/yp-download.png" align="middle" width="540" /></td></tr></table><p> - </p></li></ul></div><p> - </p></div><div class="section" title="3.4. Yocto Project Terms"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="yocto-project-terms"></a>3.4. Yocto Project Terms</h2></div></div></div><p> - Following is a list of terms and definitions users new to the Yocto Project development - environment might find helpful. - While some of these terms are universal, the list includes them just in case: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><span class="emphasis"><em>Append Files:</em></span> Files that append build information to - a recipe file. - Append files are known as BitBake append files and <code class="filename">.bbappend</code> files. - The OpenEmbedded build system expects every append file to have a corresponding and - underlying recipe (<code class="filename">.bb</code>) file. - Furthermore, the append file and the underlying recipe must have the same root filename. - The filenames can differ only in the file type suffix used (e.g. - <code class="filename">formfactor_0.0.bb</code> and <code class="filename">formfactor_0.0.bbappend</code>). - </p><p>Information in append files overrides the information in the similarly-named recipe file. - For examples of <code class="filename">.bbappend</code> file in use, see the - "<a class="link" href="#using-bbappend-files" title="4.1.4. Using .bbappend Files">Using .bbappend Files</a>" and - "<a class="link" href="#changing-recipes-kernel" title="A.5.2.4. Changing recipes-kernel">Changing <code class="filename">recipes-kernel</code></a>" - sections.</p></li><li class="listitem"><p><span class="emphasis"><em>BitBake:</em></span> The task executor and scheduler used by - the OpenEmbedded build system to build images. - For more information on BitBake, see the <a class="ulink" href="http://docs.openembedded.org/bitbake/html/" target="_top"> - BitBake documentation</a>.</p></li><li class="listitem"><p><a id="build-directory"></a><span class="emphasis"><em>Build Directory:</em></span> - This term refers to the area used by the OpenEmbedded build system for builds. - The area is created when you <code class="filename">source</code> the setup - environment script that is found in the source directory - (i.e. <code class="filename">oe-init-build-env</code>). - The <a class="link" href="#var-TOPDIR" target="_top"><code class="filename">TOPDIR</code></a> - variable points to the build directory.</p><p>You have a lot of flexibility when creating the build directory. - Following are some examples that show how to create the directory: - </p><div class="itemizedlist"><ul class="itemizedlist" type="circle"><li class="listitem"><p>Create the build directory in your current working directory - and name it <code class="filename">build</code>. - This is the default behavior. - </p><pre class="literallayout"> - $ source oe-init-build-env - </pre></li><li class="listitem"><p>Provide a directory path and specifically name the build - directory. - This next example creates a build directory named <code class="filename">YP-8.0</code> - in your home directory within the directory <code class="filename">mybuilds</code>. - If <code class="filename">mybuilds</code> does not exist, the directory is created for you: - </p><pre class="literallayout"> - $ source poky-1.2+snapshot-8.0/oe-init-build-env $HOME/mybuilds/YP-8.0 - </pre></li><li class="listitem"><p>Provide an existing directory to use as the build directory. - This example uses the existing <code class="filename">mybuilds</code> directory - as the build directory. - </p><pre class="literallayout"> - $ source poky-1.2+snapshot-8.0/oe-init-build-env $HOME/mybuilds/ - </pre></li></ul></div><p> - </p></li><li class="listitem"><p><span class="emphasis"><em>Build System:</em></span> In the context of the Yocto Project - this term refers to the OpenEmbedded build system used by the project. - This build system is based on the project known as "Poky." - For some historical information about Poky, see the - <a class="link" href="#poky">poky</a> term further along in this section. - </p></li><li class="listitem"><p><span class="emphasis"><em>Classes:</em></span> Files that provide for logic encapsulation - and inheritance allowing commonly used patterns to be defined once and easily used - in multiple recipes. - Class files end with the <code class="filename">.bbclass</code> filename extension. - </p></li><li class="listitem"><p><span class="emphasis"><em>Configuration File:</em></span> Configuration information in various - <code class="filename">.conf</code> files provides global definitions of variables. - The <code class="filename">conf/local.conf</code> configuration file in the - <a class="link" href="#build-directory">build directory</a> - contains user-defined variables that affect each build. - The <code class="filename">meta-yocto/conf/distro/poky.conf</code> configuration file - defines Yocto ‘distro’ configuration - variables used only when building with this policy. - Machine configuration files, which - are located throughout the - <a class="link" href="#source-directory">source directory</a>, define - variables for specific hardware and are only used when building for that target - (e.g. the <code class="filename">machine/beagleboard.conf</code> configuration file defines - variables for the Texas Instruments ARM Cortex-A8 development board). - Configuration files end with a <code class="filename">.conf</code> filename extension. - </p></li><li class="listitem"><p><span class="emphasis"><em>Cross-Development Toolchain:</em></span> - A collection of software development - tools and utilities that allow you to develop software for targeted architectures. - This toolchain contains cross-compilers, linkers, and debuggers that are specific to - an architecture. - You can use the OpenEmbedded build system to build cross-development toolchains in tarball - form that, when - unpacked, contain the development tools you need to cross-compile and test your software. - The Yocto Project ships with images that contain toolchains for supported architectures - as well. - Sometimes this toolchain is referred to as the meta-toolchain.</p></li><li class="listitem"><p><span class="emphasis"><em>Image:</em></span> An image is the result produced when - BitBake processes a given collection of recipes and related metadata. - Images are the binary output that run on specific hardware and for specific - use cases. - For a list of the supported image types that the Yocto Project provides, see the - "<a class="link" href="#ref-images" target="_top">Images</a>" - chapter in the Yocto Project Reference Manual.</p></li><li class="listitem"><p><a id="layer"></a><span class="emphasis"><em>Layer:</em></span> A collection of recipes representing the core, - a BSP, or an application stack. - For a discussion on BSP Layers, see the - "<a class="link" href="#bsp-layers" target="_top">BSP Layers</a>" - section in the Yocto Project Board Support Packages (BSP) Developer's Guide.</p></li><li class="listitem"><p><a id="metadata"></a><span class="emphasis"><em>Metadata:</em></span> The files that BitBake parses when - building an image. - Metadata includes recipes, classes, and configuration files.</p></li><li class="listitem"><p><span class="emphasis"><em>OE-Core:</em></span> A core set of metadata originating - with OpenEmbedded (OE) that is shared between OE and the Yocto Project. - This metadata is found in the <code class="filename">meta</code> directory of the source - directory.</p></li><li class="listitem"><p><span class="emphasis"><em>Package:</em></span> The packaged output from a baked recipe. - A package is generally the compiled binaries produced from the recipe's sources. - You ‘bake’ something by running it through BitBake.</p></li><li class="listitem"><p><a id="poky"></a><span class="emphasis"><em>Poky:</em></span> The term "poky" can mean several things. - In its most general sence, it is an open-source project that was initially developed - by OpenedHand. With OpenedHand, poky was developed off of the existing OpenEmbedded - build system becoming a build system for embedded images. - After Intel Corporation aquired OpenedHand, the project poky became the basis for - the Yocto Project's build system. - Within the Yocto Project source repositories, poky exists as a separate Git repository - that can be cloned to yield a local copy on the host system. - Thus, "poky" can refer to the local copy of the source directory used to develop within - the Yocto Project.</p></li><li class="listitem"><p><span class="emphasis"><em>Recipe:</em></span> A set of instructions for building packages. - A recipe describes where you get source code and which patches to apply. - Recipes describe dependencies for libraries or for other recipes, and they - also contain configuration and compilation options. - Recipes contain the logical unit of execution, the software/images to build, and - use the <code class="filename">.bb</code> file extension.</p></li><li class="listitem"><p><a id="source-directory"></a><span class="emphasis"><em>Source Directory:</em></span> - This term refers to the directory structure created as a result of either downloading - and unpacking a Yocto Project release tarball or creating a local copy of - <code class="filename">poky</code> Git repository <code class="filename">git://git.yoctoproject.org/poky</code>. - Sometimes you might here the term "poky directory" used to refer to this - directory structure.</p><p>The source directory contains BitBake, Documentation, metadata and - other files that all support the Yocto Project. - Consequently, you must have the source directory in place on your development - system in order to do any development using the Yocto Project.</p><p>For tarball expansion, the name of the top-level directory of the source directory - is derived from the Yocto Project release tarball. - For example, downloading and unpacking <code class="filename">poky-1.2+snapshot-8.0.tar.bz2</code> - results in a source directory whose top-level folder is named - <code class="filename">poky-1.2+snapshot-8.0</code>. - If you create a local copy of the Git repository, then you can name the repository - anything you like. - Throughout much of the documentation, <code class="filename">poky</code> is used as the name of - the top-level folder of the local copy of the poky Git repository. - So, for example, cloning the <code class="filename">poky</code> Git repository results in a - local Git repository whose top-level folder is also named <code class="filename">poky</code>.</p><p>It is important to understand the differences between the source directory created - by unpacking a released tarball as compared to cloning - <code class="filename">git://git.yoctoproject.org/poky</code>. - When you unpack a tarball, you have an exact copy of the files based on the time of - release - a fixed release point. - Any changes you make to your local files in the source directory are on top of the release. - On the other hand, when you clone the <code class="filename">poky</code> Git repository, you have an - active development repository. - In this case, any local changes you make to the source directory can be later applied - to active development branches of the upstream <code class="filename">poky</code> Git - repository.</p><p>Finally, if you want to track a set of local changes while starting from the same point - as a release tarball, you can create a local Git branch that - reflects the exact copy of the files at the time of their release. - You do this using Git tags that are part of the repository.</p><p>For more information on concepts around Git repositories, branches, and tags, - see the - "<a class="link" href="#repositories-tags-and-branches" title="3.6.1. Repositories, Tags, and Branches">Repositories, Tags, and Branches</a>" - section.</p></li><li class="listitem"><p><span class="emphasis"><em>Tasks:</em></span> Arbitrary groups of software Recipes. - You simply use Tasks to hold recipes that, when built, usually accomplish a single task. - For example, a task could contain the recipes for a company’s proprietary or value-add software. - Or, the task could contain the recipes that enable graphics. - A task is really just another recipe. - Because task files are recipes, they end with the <code class="filename">.bb</code> filename - extension.</p></li><li class="listitem"><p><span class="emphasis"><em>Upstream:</em></span> A reference to source code or repositories - that are not local to the development system but located in a master area that is controlled - by the maintainer of the source code. - For example, in order for a developer to work on a particular piece of code, they need to - first get a copy of it from an "upstream" source.</p></li></ul></div><p> - </p></div><div class="section" title="3.5. Licensing"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="licensing"></a>3.5. Licensing</h2></div></div></div><p> - Because open source projects are open to the public, they have different licensing structures in place. - License evolution for both Open Source and Free Software has an interesting history. - If you are interested in this history, you can find basic information here: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><a class="ulink" href="http://en.wikipedia.org/wiki/Open-source_license" target="_top">Open source license history</a> - </p></li><li class="listitem"><p><a class="ulink" href="http://en.wikipedia.org/wiki/Free_software_license" target="_top">Free software license - history</a></p></li></ul></div><p> - </p><p> - In general, the Yocto Project is broadly licensed under the Massachusetts Institute of Technology - (MIT) License. - MIT licensing permits the reuse of software within proprietary software as long as the - license is distributed with that software. - MIT is also compatible with the GNU General Public License (GPL). - Patches to the Yocto Project follow the upstream licensing scheme. - You can find information on the MIT license at - <a class="ulink" href="http://www.opensource.org/licenses/mit-license.php" target="_top">here</a>. - You can find information on the GNU GPL <a class="ulink" href="http://www.opensource.org/licenses/LGPL-3.0" target="_top"> - here</a>. - </p><p> - When you build an image using Yocto Project, the build process uses a known list of licenses to - ensure compliance. - You can find this list in the Yocto Project files directory at - <code class="filename">meta/files/common-licenses</code>. - Once the build completes, the list of all licenses found and used during that build are - kept in the - <a class="link" href="#build-directory">build directory</a> at - <code class="filename">tmp/deploy/images/licenses</code>. - </p><p> - If a module requires a license that is not in the base list, the build process - generates a warning during the build. - These tools make it easier for a developer to be certain of the licenses with which - their shipped products must comply. - However, even with these tools it is still up to the developer to resolve potential licensing issues. - </p><p> - The base list of licenses used by the build process is a combination of the Software Package - Data Exchange (SPDX) list and the Open Source Initiative (OSI) projects. - <a class="ulink" href="http://spdx.org" target="_top">SPDX Group</a> is a working group of the Linux Foundation - that maintains a specification - for a standard format for communicating the components, licenses, and copyrights - associated with a software package. - <a class="ulink" href="http://opensource.org" target="_top">OSI</a> is a corporation dedicated to the Open Source - Definition and the effort for reviewing and approving licenses that are OSD-conformant. - </p><p> - You can find a list of the combined SPDX and OSI licenses that the Yocto Project uses - <a class="ulink" href="http://git.yoctoproject.org/cgit/cgit.cgi/poky/tree/meta/files/common-licenses" target="_top">here</a>. - This wiki page discusses the license infrastructure used by the Yocto Project. - </p></div><div class="section" title="3.6. Git"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="git"></a>3.6. Git</h2></div></div></div><p> - The Yocto Project uses Git, which is a free, open source distributed version control system. - Git supports distributed development, non-linear development, and can handle large projects. - It is best that you have some fundamental understanding of how Git tracks projects and - how to work with Git if you are going to use Yocto Project for development. - This section provides a quick overview of how Git works and provides you with a summary - of some essential Git commands. - </p><p> - For more information on Git, see - <a class="ulink" href="http://git-scm.com/documentation" target="_top">http://git-scm.com/documentation</a>. - If you need to download Git, go to <a class="ulink" href="http://git-scm.com/download" target="_top">http://git-scm.com/download</a>. - </p><div class="section" title="3.6.1. Repositories, Tags, and Branches"><div class="titlepage"><div><div><h3 class="title"><a id="repositories-tags-and-branches"></a>3.6.1. Repositories, Tags, and Branches</h3></div></div></div><p> - As mentioned earlier in section - "<a class="link" href="#yocto-project-repositories" title="3.3. Yocto Project Source Repositories">Yocto Project Source Repositories</a>", - the Yocto Project maintains source repositories at - <a class="ulink" href="http://git.yoctoproject.org/cgit.cgi" target="_top">http://git.yoctoproject.org/cgit.cgi</a>. - If you look at this web-interface of the repositories, each item is a separate - Git repository. - </p><p> - Git repositories use branching techniques that track content change (not files) - within a project (e.g. a new feature or updated documentation). - Creating a tree-like structure based on project divergence allows for excellent historical - information over the life of a project. - This methodology also allows for an environment in which you can do lots of - local experimentation on a project as you develop changes or new features. - </p><p> - A Git repository represents all development efforts for a given project. - For example, the Git repository <code class="filename">poky</code> contains all changes - and developments for Poky over the course of its entire life. - That means that all changes that make up all releases are captured. - The repository maintains a complete history of changes. - </p><p> - You can create a local copy of any repository by "cloning" it with the Git - <code class="filename">clone</code> command. - When you clone a Git repository, you end up with an identical copy of the - repository on your development system. - Once you have a local copy of a repository, you can take steps to develop locally. - For examples on how to clone Git repositories, see the section - "<a class="link" href="#getting-setup" title="2.2. Getting Set Up">Getting Set Up</a>" earlier in this manual. - </p><p> - It is important to understand that Git tracks content change and not files. - Git uses "branches" to organize different development efforts. - For example, the <code class="filename">poky</code> repository has - <code class="filename">laverne</code>, <code class="filename">bernard</code>, - <code class="filename">edison</code>, <code class="filename">denzil</code> and - <code class="filename">master</code> branches among - others. - You can see all the branches by going to - <a class="ulink" href="http://git.yoctoproject.org/cgit.cgi/poky/" target="_top">http://git.yoctoproject.org/cgit.cgi/poky/</a> and - clicking on the - <code class="filename"><a class="ulink" href="http://git.yoctoproject.org/cgit.cgi/poky/refs/heads" target="_top">[...]</a></code> - link beneath the "Branch" heading. - </p><p> - Each of these branches represents a specific area of development. - The <code class="filename">master</code> branch represents the current or most recent - development. - All other branches represent off-shoots of the <code class="filename">master</code> - branch. - </p><p> - When you create a local copy of a Git repository, the copy has the same set - of branches as the original. - This means you can use Git to create a local working area (also called a branch) - that tracks a specific development branch from the source Git repository. - in other words, you can define your local Git environment to work on any development - branch in the repository. - To help illustrate, here is a set of commands that creates a local copy of the - <code class="filename">poky</code> Git repository and then creates and checks out a local - Git branch that tracks the Yocto Project 1.3 Release (1.2+snapshot) development: - </p><pre class="literallayout"> - $ cd ~ - $ git clone git://git.yoctoproject.org/poky - $ cd poky - $ git checkout -b 1.2+snapshot origin/1.2+snapshot - </pre><p> - In this example, the name of the top-level directory of your local Yocto Project - Files Git repository is <code class="filename">poky</code>, - and the name of the local working area (or local branch) you have created and checked - out is <code class="filename">1.2+snapshot</code>. - The files in your repository now reflect the same files that are in the - <code class="filename">1.2+snapshot</code> development branch of the Yocto Project's - <code class="filename">poky</code> repository. - It is important to understand that when you create and checkout a - local working branch based on a branch name, - your local environment matches the "tip" of that development branch - at the time you created your local branch, which could be - different than the files at the time of a similarly named release. - In other words, creating and checking out a local branch based on the - <code class="filename">1.2+snapshot</code> branch name is not the same as creating and - checking out a local branch based on the <code class="filename">1.2+snapshot-1.3</code> - release. - Keep reading to see how you create a local snapshot of a Yocto Project Release. - </p><p> - Git uses "tags" to mark specific changes in a repository. - Typically, a tag is used to mark a special point such as the final change - before a project is released. - You can see the tags used with the <code class="filename">poky</code> Git repository - by going to <a class="ulink" href="http://git.yoctoproject.org/cgit.cgi/poky/" target="_top">http://git.yoctoproject.org/cgit.cgi/poky/</a> and - clicking on the - <code class="filename"><a class="ulink" href="http://git.yoctoproject.org/cgit.cgi/poky/refs/tags" target="_top">[...]</a></code> - link beneath the "Tag" heading. - </p><p> - Some key tags are <code class="filename">laverne-4.0</code>, <code class="filename">bernard-5.0</code>, - and <code class="filename">1.2+snapshot-8.0</code>. - These tags represent Yocto Project releases. - </p><p> - When you create a local copy of the Git repository, you also have access to all the - tags. - Similar to branches, you can create and checkout a local working Git branch based - on a tag name. - When you do this, you get a snapshot of the Git repository that reflects - the state of the files when the change was made associated with that tag. - The most common use is to checkout a working branch that matches a specific - Yocto Project release. - Here is an example: - </p><pre class="literallayout"> - $ cd ~ - $ git clone git://git.yoctoproject.org/poky - $ cd poky - $ git checkout -b my-1.2+snapshot-8.0 1.2+snapshot-8.0 - </pre><p> - In this example, the name of the top-level directory of your local Yocto Project - Files Git repository is <code class="filename">poky</code>. - And, the name of the local branch you have created and checked out is - <code class="filename">my-1.2+snapshot-8.0</code>. - The files in your repository now exactly match the Yocto Project 1.3 - Release tag (<code class="filename">1.2+snapshot-8.0</code>). - It is important to understand that when you create and checkout a local - working branch based on a tag, your environment matches a specific point - in time and not a development branch. - </p></div><div class="section" title="3.6.2. Basic Commands"><div class="titlepage"><div><div><h3 class="title"><a id="basic-commands"></a>3.6.2. Basic Commands</h3></div></div></div><p> - Git has an extensive set of commands that lets you manage changes and perform - collaboration over the life of a project. - Conveniently though, you can manage with a small set of basic operations and workflows - once you understand the basic philosophy behind Git. - You do not have to be an expert in Git to be functional. - A good place to look for instruction on a minimal set of Git commands is - <a class="ulink" href="http://git-scm.com/documentation" target="_top">here</a>. - If you need to download Git, you can do so - <a class="ulink" href="http://git-scm.com/download" target="_top">here</a>. - </p><p> - If you don’t know much about Git, we suggest you educate - yourself by visiting the links previously mentioned. - </p><p> - The following list briefly describes some basic Git operations as a way to get started. - As with any set of commands, this list (in most cases) simply shows the base command and - omits the many arguments they support. - See the Git documentation for complete descriptions and strategies on how to use these commands: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><span class="emphasis"><em><code class="filename">git init</code>:</em></span> Initializes an empty Git repository. - You cannot use Git commands unless you have a <code class="filename">.git</code> repository.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">git clone</code>:</em></span> Creates a clone of a repository. - During collaboration, this command allows you to create a local repository that is on - equal footing with a fellow developer’s repository.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">git add</code>:</em></span> Adds updated file contents - to the index that - Git uses to track changes. - You must add all files that have changed before you can commit them.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">git commit</code>:</em></span> Creates a “commit” that documents - the changes you made. - Commits are used for historical purposes, for determining if a maintainer of a project - will allow the change, and for ultimately pushing the change from your local Git repository - into the project’s upstream (or master) repository.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">git status</code>:</em></span> Reports any modified files that - possibly need to be added and committed.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">git checkout <branch-name></code>:</em></span> Changes - your working branch. - This command is analogous to “cd”.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">git checkout –b <working-branch></code>:</em></span> Creates - a working branch on your local machine where you can isolate work. - It is a good idea to use local branches when adding specific features or changes. - This way if you don’t like what you have done you can easily get rid of the work.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">git branch</code>:</em></span> Reports existing branches and - tells you which branch in which you are currently working.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">git branch -D <branch-name></code>:</em></span> - Deletes an existing branch. - You need to be in a branch other than the one you are deleting - in order to delete <branch-name>.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">git pull</code>:</em></span> Retrieves information - from an upstream Git - repository and places it in your local Git repository. - You use this command to make sure you are synchronized with the repository - from which you are basing changes (.e.g. the master repository).</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">git push</code>:</em></span> Sends all your local changes you - have committed to an upstream Git repository (e.g. a contribution repository). - The maintainer of the project draws from these repositories when adding your changes to the - project’s master repository.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">git merge</code>:</em></span> Combines or adds changes from one - local branch of your repository with another branch. - When you create a local Git repository, the default branch is named “master”. - A typical workflow is to create a temporary branch for isolated work, make and commit your - changes, switch to your local master branch, merge the changes from the temporary branch into the - local master branch, and then delete the temporary branch.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">git cherry-pick</code>:</em></span> Choose and apply specific - commits from one branch into another branch. - There are times when you might not be able to merge all the changes in one branch with - another but need to pick out certain ones.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">gitk</code>:</em></span> Provides a GUI view of the branches - and changes in your local Git repository. - This command is a good way to graphically see where things have diverged in your - local repository.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">git log</code>:</em></span> Reports a history of your changes to the - repository.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">git diff</code>:</em></span> Displays line-by-line differences - between your local working files and the same files in the upstream Git repository that your - branch currently tracks.</p></li></ul></div><p> - </p></div></div><div class="section" title="3.7. Workflows"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="workflows"></a>3.7. Workflows</h2></div></div></div><p> - This section provides some overview on workflows using Git. - In particular, the information covers basic practices that describe roles and actions in a - collaborative development environment. - Again, if you are familiar with this type of development environment, you might want to just - skip this section. - </p><p> - The Yocto Project files are maintained using Git in a "master" branch whose Git history - tracks every change and whose structure provides branches for all diverging functionality. - Although there is no need to use Git, many open source projects do so. - For the Yocto Project, a key individual called the "maintainer" is responsible for the "master" - branch of the Git repository. - The "master" branch is the “upstream” repository where the final builds of the project occur. - The maintainer is responsible for allowing changes in from other developers and for - organizing the underlying branch structure to reflect release strategies and so forth. - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>You can see who is the maintainer for Yocto Project files by examining the - <code class="filename">distro_tracking_fields.inc</code> file in the Yocto Project - <code class="filename">meta/conf/distro/include</code> directory.</div><p> - </p><p> - The project also has contribution repositories known as “contrib” areas. - These areas temporarily hold changes to the project that have been submitted or committed - by the Yocto Project development team and by community members that contribute to the project. - The maintainer determines if the changes are qualified to be moved from the "contrib" areas - into the "master" branch of the Git repository. - </p><p> - Developers (including contributing community members) create and maintain cloned repositories - of the upstream "master" branch. - These repositories are local to their development platforms and are used to develop changes. - When a developer is satisfied with a particular feature or change, they “push” the changes - to the appropriate "contrib" repository. - </p><p> - Developers are responsible for keeping their local repository up-to-date with "master". - They are also responsible for straightening out any conflicts that might arise within files - that are being worked on simultaneously by more than one person. - All this work is done locally on the developer’s machine before anything is pushed to a - "contrib" area and examined at the maintainer’s level. - </p><p> - A somewhat formal method exists by which developers commit changes and push them into the - "contrib" area and subsequently request that the maintainer include them into "master" - This process is called “submitting a patch” or “submitting a change.” - </p><p> - To summarize the environment: we have a single point of entry for changes into the project’s - "master" branch of the Git repository, which is controlled by the project’s maintainer. - And, we have a set of developers who independently develop, test, and submit changes - to "contrib" areas for the maintainer to examine. - The maintainer then chooses which changes are going to become a permanent part of the project. - </p><p> - </p><table border="0" summary="manufactured viewport for HTML img" cellspacing="0" cellpadding="0" width="540"><tr style="height: 270px"><td align="left"><img src="figures/git-workflow.png" align="left" height="270" /></td></tr></table><p> - </p><p> - While each development environment is unique, there are some best practices or methods - that help development run smoothly. - The following list describes some of these practices. - For more information about Git workflows, see the workflow topics in the - <a class="ulink" href="http://book.git-scm.com" target="_top">Git Community Book</a>. - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><span class="emphasis"><em>Make Small Changes:</em></span> It is best to keep the changes you commit - small as compared to bundling many disparate changes into a single commit. - This practice not only keeps things manageable but also allows the maintainer - to more easily include or refuse changes.</p><p>It is also good practice to leave the repository in a state that allows you to - still successfully build your project. In other words, do not commit half of a feature, - then add the other half in a separate, later commit. - Each commit should take you from one buildable project state to another - buildable state.</p></li><li class="listitem"><p><span class="emphasis"><em>Use Branches Liberally:</em></span> It is very easy to create, use, and - delete local branches in your working Git repository. - You can name these branches anything you like. - It is helpful to give them names associated with the particular feature or change - on which you are working. - Once you are done with a feature or change, simply discard the branch.</p></li><li class="listitem"><p><span class="emphasis"><em>Merge Changes:</em></span> The <code class="filename">git merge</code> - command allows you to take the - changes from one branch and fold them into another branch. - This process is especially helpful when more than a single developer might be working - on different parts of the same feature. - Merging changes also automatically identifies any collisions or “conflicts” - that might happen as a result of the same lines of code being altered by two different - developers.</p></li><li class="listitem"><p><span class="emphasis"><em>Manage Branches:</em></span> Because branches are easy to use, you should - use a system where branches indicate varying levels of code readiness. - For example, you can have a “work” branch to develop in, a “test” branch where the code or - change is tested, a “stage” branch where changes are ready to be committed, and so forth. - As your project develops, you can merge code across the branches to reflect ever-increasing - stable states of the development.</p></li><li class="listitem"><p><span class="emphasis"><em>Use Push and Pull:</em></span> The push-pull workflow is based on the - concept of developers “pushing” local commits to a remote repository, which is - usually a contribution repository. - This workflow is also based on developers “pulling” known states of the project down into their - local development repositories. - The workflow easily allows you to pull changes submitted by other developers from the - upstream repository into your work area ensuring that you have the most recent software - on which to develop. - The Yocto Project has two scripts named <code class="filename">create-pull-request</code> and - <code class="filename">send-pull-request</code> that ship with the release to facilitate this - workflow. - You can find these scripts in the local Yocto Project files Git repository in - the <code class="filename">scripts</code> directory.</p></li><li class="listitem"><p><span class="emphasis"><em>Patch Workflow:</em></span> This workflow allows you to notify the - maintainer through an email that you have a change (or patch) you would like considered - for the "master" branch of the Git repository. - To send this type of change you format the patch and then send the email using the Git commands - <code class="filename">git format-patch</code> and <code class="filename">git send-email</code>. - You can find information on how to submit later in this chapter.</p></li></ul></div><p> - </p></div><div class="section" title="3.8. Tracking Bugs"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="tracking-bugs"></a>3.8. Tracking Bugs</h2></div></div></div><p> - The Yocto Project uses its own implementation of - <a class="ulink" href="http://www.bugzilla.org/about/" target="_top">Bugzilla</a> to track bugs. - Implementations of Bugzilla work well for group development because they track bugs and code - changes, can be used to communicate changes and problems with developers, can be used to - submit and review patches, and can be used to manage quality assurance. - The home page for the Yocto Project implementation of Bugzilla is - <a class="ulink" href="http://bugzilla.yoctoproject.org" target="_top">http://bugzilla.yoctoproject.org</a>. - </p><p> - Sometimes it is helpful to submit, investigate, or track a bug against the Yocto Project itself - such as when discovering an issue with some component of the build system that acts contrary - to the documentation or your expectations. - Following is the general procedure for submitting a new bug using the Yocto Project - Bugzilla. - You can find more information on defect management, bug tracking, and feature request - processes all accomplished through the Yocto Project Bugzilla on the wiki page - <a class="ulink" href="https://wiki.yoctoproject.org/wiki/Bugzilla_Configuration_and_Bug_Tracking" target="_top">here</a>. - </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Always use the Yocto Project implementation of Bugzilla to submit - a bug.</p></li><li class="listitem"><p>When submitting a new bug, be sure to choose the appropriate - Classification, Product, and Component for which the issue was found. - Defects for Yocto Project fall into one of four classifications: Yocto Projects, - Infrastructure, Poky, and Yocto Metadata Layers. - Each of these Classifications break down into multiple Products and, in some - cases, multiple Components.</p></li><li class="listitem"><p>Use the bug form to choose the correct Hardware and Architecture - for which the bug applies.</p></li><li class="listitem"><p>Indicate the Yocto Project version you were using when the issue - occurred.</p></li><li class="listitem"><p>Be sure to indicate the Severity of the bug. - Severity communicates how the bug impacted your work.</p></li><li class="listitem"><p>Provide a brief summary of the issue. - Try to limit your summary to just a line or two and be sure to capture the - essence of the issue.</p></li><li class="listitem"><p>Provide a detailed description of the issue. - You should provide as much detail as you can about the context, behavior, output, - and so forth that surround the issue. - You can even attach supporting files for output or log by using the "Add an attachment" - button.</p></li><li class="listitem"><p>Submit the bug by clicking the "Submit Bug" button.</p></li></ol></div><p> - </p></div><div class="section" title="3.9. How to Submit a Change"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="how-to-submit-a-change"></a>3.9. How to Submit a Change</h2></div></div></div><p> - Contributions to the Yocto Project and OpenEmbedded are very welcome. - Because the system is extremely configurable and flexible, we recognize that developers - will want to extend, configure or optimize it for their specific uses. - You should send patches to the appropriate mailing list so that they - can be reviewed and merged by the appropriate maintainer. - For a list of the Yocto Project and related mailing lists, see the - "<a class="link" href="#resources-mailinglist" target="_top">Mailing lists</a>" section in - the Yocto Project Reference Manual. - </p><p> - The following is some guidance on which mailing list to use for what type of change: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>For changes to the core metadata, send your patch to the - <a class="ulink" href="http://lists.linuxtogo.org/cgi-bin/mailman/listinfo/openembedded-core" target="_top">openembedded-core</a> mailing list. - For example, a change to anything under the <code class="filename">meta</code> or - <code class="filename">scripts</code> directories - should be sent to this mailing list.</p></li><li class="listitem"><p>For changes to BitBake (anything under the <code class="filename">bitbake</code> - directory), send your patch to the - <a class="ulink" href="http://lists.linuxtogo.org/cgi-bin/mailman/listinfo/bitbake-devel" target="_top">bitbake-devel</a> mailing list.</p></li><li class="listitem"><p>For changes to <code class="filename">meta-yocto</code>, send your patch to the - <a class="ulink" href="http://lists.yoctoproject.org/listinfo/poky" target="_top">poky</a> mailing list.</p></li><li class="listitem"><p>For changes to other layers hosted on yoctoproject.org (unless the - layer's documentation specifies otherwise), tools, and Yocto Project - documentation, use the - <a class="ulink" href="http://lists.yoctoproject.org/listinfo/yocto" target="_top">yocto</a> mailing list.</p></li><li class="listitem"><p>For additional recipes that do not fit into the core metadata, - you should determine which layer the recipe should go into and submit the - change in the manner recommended by the documentation (e.g. README) supplied - with the layer. If in doubt, please ask on the - <a class="ulink" href="http://lists.yoctoproject.org/listinfo/yocto" target="_top">yocto</a> or - <a class="ulink" href="http://lists.linuxtogo.org/cgi-bin/mailman/listinfo/openembedded-devel" target="_top">openembedded-devel</a> - mailing lists.</p></li></ul></div><p> - </p><p> - When you send a patch, be sure to include a "Signed-off-by:" - line in the same style as required by the Linux kernel. - Adding this line signifies that you, the submitter, have agreed to the Developer's Certificate of Origin 1.1 - as follows: - </p><pre class="literallayout"> - Developer's Certificate of Origin 1.1 - - By making a contribution to this project, I certify that: - - (a) The contribution was created in whole or in part by me and I - have the right to submit it under the open source license - indicated in the file; or - - (b) The contribution is based upon previous work that, to the best - of my knowledge, is covered under an appropriate open source - license and I have the right under that license to submit that - work with modifications, whether created in whole or in part - by me, under the same open source license (unless I am - permitted to submit under a different license), as indicated - in the file; or - - (c) The contribution was provided directly to me by some other - person who certified (a), (b) or (c) and I have not modified - it. - - (d) I understand and agree that this project and the contribution - are public and that a record of the contribution (including all - personal information I submit with it, including my sign-off) is - maintained indefinitely and may be redistributed consistent with - this project or the open source license(s) involved. - </pre><p> - </p><p> - In a collaborative environment, it is necessary to have some sort of standard - or method through which you submit changes. - Otherwise, things could get quite chaotic. - One general practice to follow is to make small, controlled changes. - Keeping changes small and isolated aids review, makes merging/rebasing easier - and keeps the change history clean when anyone needs to refer to it in future. - </p><p> - When you make a commit, you must follow certain standards established by the - OpenEmbedded and Yocto Project development teams. - For each commit, you must provide a single-line summary of the change and you - should almost always provide a more detailed description of what you did (i.e. - the body of the commit message). - The only exceptions for not providing a detailed description would be if your - change is a simple, self-explanatory change that needs no description. - Here are the guidelines for composing a commit message: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>Provide a single-line, short summary of the change. - This summary is typically viewable in the "shortlist" of changes. - Thus, providing something short and descriptive that gives the reader - a summary of the change is useful when viewing a list of many commits. - This should be prefixed by the recipe name (if changing a recipe), or - else the short form path to the file being changed. - </p></li><li class="listitem"><p>For the body of the commit message, provide detailed information - that describes what you changed, why you made the change, and the approach - you used. It may also be helpful if you mention how you tested the change. - Provide as much detail as you can in the body of the commit message. - </p></li><li class="listitem"><p>If the change addresses a specific bug or issue that is - associated with a bug-tracking ID, include a reference to that ID in - your detailed description. - For example, the Yocto Project uses a specific convention for bug - references - any commit that addresses a specific bug should include the - bug ID in the description (typically at the beginning) as follows: - </p><pre class="literallayout"> - [YOCTO #<bug-id>] - - <detailed description of change> - </pre></li></ul></div><p> - </p><p> - You can find more guidance on creating well-formed commit messages at this OpenEmbedded - wiki page: - <a class="ulink" href="http://www.openembedded.org/wiki/Commit_Patch_Message_Guidelines" target="_top">http://www.openembedded.org/wiki/Commit_Patch_Message_Guidelines</a>. - </p><p> - Following are general instructions for both pushing changes upstream and for submitting - changes as patches. - </p><div class="section" title="3.9.1. Using Scripts to Push a Change Upstream and Request a Pull"><div class="titlepage"><div><div><h3 class="title"><a id="pushing-a-change-upstream"></a>3.9.1. Using Scripts to Push a Change Upstream and Request a Pull</h3></div></div></div><p> - The basic flow for pushing a change to an upstream "contrib" Git repository is as follows: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>Make your changes in your local Git repository.</p></li><li class="listitem"><p>Stage your changes by using the <code class="filename">git add</code> - command on each file you changed.</p></li><li class="listitem"><p>Commit the change by using the <code class="filename">git commit</code> - command and push it to the "contrib" repository. - Be sure to provide a commit message that follows the project’s commit message standards - as described earlier.</p></li><li class="listitem"><p>Notify the maintainer that you have pushed a change by making a pull - request. - The Yocto Project provides two scripts that conveniently let you generate and send - pull requests to the Yocto Project. - These scripts are <code class="filename">create-pull-request</code> and - <code class="filename">send-pull-request</code>. - You can find these scripts in the <code class="filename">scripts</code> directory of the - Yocto Project file structure.</p><p>Using these scripts correctly formats the requests without introducing any - whitespace or HTML formatting. - The maintainer that receives your patches needs to be able to save and apply them - directly from your emails. - Using these scripts is the preferred method for sending patches.</p><p>For help on using these scripts, simply provide the - <code class="filename">-h</code> argument as follows: - </p><pre class="literallayout"> - $ ~/poky/scripts/create-pull-request -h - $ ~/poky/scripts/send-pull-request -h - </pre></li></ul></div><p> - </p><p> - You can find general Git information on how to push a change upstream in the - <a class="ulink" href="http://book.git-scm.com/3_distributed_workflows.html" target="_top">Git Community Book</a>. - </p></div><div class="section" title="3.9.2. Using Email to Submit a Patch"><div class="titlepage"><div><div><h3 class="title"><a id="submitting-a-patch"></a>3.9.2. Using Email to Submit a Patch</h3></div></div></div><p> - You can submit patches without using the <code class="filename">create-pull-request</code> and - <code class="filename">send-pull-request</code> scripts described in the previous section. - Keep in mind, the preferred method is to use the scripts, however. - </p><p> - Depending on the components changed, you need to submit the email to a specific - mailing list. - For some guidance on which mailing list to use, see the list in the - "<a class="link" href="#how-to-submit-a-change" title="3.9. How to Submit a Change">How to Submit a Change</a>" section - earlier in this manual. - For a description of the available mailing lists, see - "<a class="link" href="#resources-mailinglist" target="_top">Mailing Lists</a>" - section in the Yocto Project Reference Manual. - </p><p> - Here is the general procedure on how to submit a patch through email without using the - scripts: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>Make your changes in your local Git repository.</p></li><li class="listitem"><p>Stage your changes by using the <code class="filename">git add</code> - command on each file you changed.</p></li><li class="listitem"><p>Commit the change by using the - <code class="filename">git commit --signoff</code> command. - Using the <code class="filename">--signoff</code> option identifies you as the person - making the change and also satisfies the Developer's Certificate of - Origin (DCO) shown earlier.</p><p>When you form a commit you must follow certain standards established by the - Yocto Project development team. - See the earlier section - "<a class="link" href="#how-to-submit-a-change" title="3.9. How to Submit a Change">How to Submit a Change</a>" - for Yocto Project commit message standards.</p></li><li class="listitem"><p>Format the commit into an email message. - To format commits, use the <code class="filename">git format-patch</code> command. - When you provide the command, you must include a revision list or a number of patches - as part of the command. - For example, these two commands each take the most recent single commit and - format it as an email message in the current directory: - </p><pre class="literallayout"> - $ git format-patch -1 - $ git format-patch HEAD~ - </pre><p>After the command is run, the current directory contains a - numbered <code class="filename">.patch</code> file for the commit.</p><p>If you provide several commits as part of the command, - the <code class="filename">git format-patch</code> command produces a numbered - series of files in the current directory – one for each commit. - If you have more than one patch, you should also use the - <code class="filename">--cover</code> option with the command, which generates a - cover letter as the first "patch" in the series. - You can then edit the cover letter to provide a description for - the series of patches. - For information on the <code class="filename">git format-patch</code> command, - see <code class="filename">GIT_FORMAT_PATCH(1)</code> displayed using the - <code class="filename">man git-format-patch</code> command.</p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>If you are or will be a frequent contributor to the Yocto Project - or to OpenEmbedded, you might consider requesting a contrib area and the - necessary associated rights.</div></li><li class="listitem"><p>Import the files into your mail client by using the - <code class="filename">git send-email</code> command. - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>In order to use <code class="filename">git send-email</code>, you must have the - the proper Git packages installed. - For Ubuntu and Fedora the package is <code class="filename">git-email</code>.</div><p>The <code class="filename">git send-email</code> command sends email by using a local - or remote Mail Transport Agent (MTA) such as - <code class="filename">msmtp</code>, <code class="filename">sendmail</code>, or through a direct - <code class="filename">smtp</code> configuration in your Git <code class="filename">config</code> - file. - If you are submitting patches through email only, it is very important - that you submit them without any whitespace or HTML formatting that - either you or your mailer introduces. - The maintainer that receives your patches needs to be able to save and - apply them directly from your emails. - A good way to verify that what you are sending will be applicable by the - maintainer is to do a dry run and send them to yourself and then - save and apply them as the maintainer would.</p><p>The <code class="filename">git send-email</code> command is the preferred method - for sending your patches since there is no risk of compromising whitespace - in the body of the message, which can occur when you use your own mail client. - The command also has several options that let you - specify recipients and perform further editing of the email message. - For information on how to use the <code class="filename">git send-email</code> command, - use the <code class="filename">man git-send-email</code> command.</p></li></ul></div><p> - </p></div></div></div> - - <div class="chapter" title="Chapter 4. Common Tasks"><div class="titlepage"><div><div><h2 class="title"><a id="extendpoky"></a>Chapter 4. Common Tasks</h2></div></div></div><div class="toc"><dl><dt><span class="section"><a href="#understanding-and-creating-layers">4.1. Understanding and Creating Layers</a></span></dt><dd><dl><dt><span class="section"><a href="#yocto-project-layers">4.1.1. Layers</a></span></dt><dt><span class="section"><a href="#creating-your-own-layer">4.1.2. Creating Your Own Layer</a></span></dt><dt><span class="section"><a href="#enabling-your-layer">4.1.3. Enabling Your Layer</a></span></dt><dt><span class="section"><a href="#using-bbappend-files">4.1.4. Using .bbappend Files</a></span></dt><dt><span class="section"><a href="#prioritizing-your-layer">4.1.5. Prioritizing Your Layer</a></span></dt><dt><span class="section"><a href="#managing-layers">4.1.6. Managing Layers</a></span></dt></dl></dd><dt><span class="section"><a href="#usingpoky-extend-customimage">4.2. Customizing Images</a></span></dt><dd><dl><dt><span class="section"><a href="#usingpoky-extend-customimage-custombb">4.2.1. Customizing Images Using Custom .bb Files</a></span></dt><dt><span class="section"><a href="#usingpoky-extend-customimage-customtasks">4.2.2. Customizing Images Using Custom Tasks</a></span></dt><dt><span class="section"><a href="#usingpoky-extend-customimage-imagefeatures">4.2.3. Customizing Images Using Custom <code class="filename">IMAGE_FEATURES</code> and - <code class="filename">EXTRA_IMAGE_FEATURES</code></a></span></dt><dt><span class="section"><a href="#usingpoky-extend-customimage-localconf">4.2.4. Customizing Images Using <code class="filename">local.conf</code></a></span></dt></dl></dd><dt><span class="section"><a href="#usingpoky-extend-addpkg">4.3. Adding a Package</a></span></dt><dd><dl><dt><span class="section"><a href="#usingpoky-extend-addpkg-singlec">4.3.1. Single .c File Package (Hello World!)</a></span></dt><dt><span class="section"><a href="#usingpoky-extend-addpkg-autotools">4.3.2. Autotooled Package</a></span></dt><dt><span class="section"><a href="#usingpoky-extend-addpkg-makefile">4.3.3. Makefile-Based Package</a></span></dt><dt><span class="section"><a href="#splitting-an-application-into-multiple-packages">4.3.4. Splitting an Application into Multiple Packages</a></span></dt><dt><span class="section"><a href="#including-static-library-files">4.3.5. Including Static Library Files</a></span></dt><dt><span class="section"><a href="#usingpoky-extend-addpkg-postinstalls">4.3.6. Post Install Scripts</a></span></dt></dl></dd><dt><span class="section"><a href="#platdev-newmachine">4.4. Adding a New Machine</a></span></dt><dd><dl><dt><span class="section"><a href="#platdev-newmachine-conffile">4.4.1. Adding the Machine Configuration File</a></span></dt><dt><span class="section"><a href="#platdev-newmachine-kernel">4.4.2. Adding a Kernel for the Machine</a></span></dt><dt><span class="section"><a href="#platdev-newmachine-formfactor">4.4.3. Adding a Formfactor Configuration File</a></span></dt></dl></dd><dt><span class="section"><a href="#building-multiple-architecture-libraries-into-one-image">4.5. Combining Multiple Versions of Library Files into One Image</a></span></dt><dd><dl><dt><span class="section"><a href="#preparing-to-use-multilib">4.5.1. Preparing to use Multilib</a></span></dt><dt><span class="section"><a href="#using-multilib">4.5.2. Using Multilib</a></span></dt><dt><span class="section"><a href="#additional-implementation-details">4.5.3. Additional Implementation Details</a></span></dt></dl></dd><dt><span class="section"><a href="#configuring-the-kernel">4.6. Configuring the Kernel</a></span></dt><dd><dl><dt><span class="section"><a href="#using-menuconfig">4.6.1. Using <code class="filename">menuconfig</code></a></span></dt><dt><span class="section"><a href="#creating-config-fragments">4.6.2. Creating Configuration Fragments</a></span></dt><dt><span class="section"><a href="#fine-tuning-the-kernel-configuration-file">4.6.3. Fine-tuning the Kernel Configuration File</a></span></dt></dl></dd><dt><span class="section"><a href="#usingpoky-changes-updatingimages">4.7. Updating Existing Images</a></span></dt><dt><span class="section"><a href="#usingpoky-changes-prbump">4.8. Incrementing a Package Revision Number</a></span></dt><dt><span class="section"><a href="#usingpoky-configuring-DISTRO_PN_ALIAS">4.9. Handling a Package Name Alias</a></span></dt><dt><span class="section"><a href="#building-software-from-an-external-source">4.10. Building Software from an External Source</a></span></dt><dt><span class="section"><a href="#excluding-recipes-from-the-build">4.11. Excluding Recipes From the Build</a></span></dt><dt><span class="section"><a href="#platdev-appdev-srcrev">4.12. Using an External SCM</a></span></dt><dt><span class="section"><a href="#platdev-gdb-remotedebug">4.13. Debugging With the GNU Project Debugger (GDB) Remotely</a></span></dt><dd><dl><dt><span class="section"><a href="#platdev-gdb-remotedebug-launch-gdbserver">4.13.1. Launching Gdbserver on the Target</a></span></dt><dt><span class="section"><a href="#platdev-gdb-remotedebug-launch-gdb">4.13.2. Launching GDB on the Host Computer</a></span></dt></dl></dd><dt><span class="section"><a href="#platdev-oprofile">4.14. Profiling with OProfile</a></span></dt><dd><dl><dt><span class="section"><a href="#platdev-oprofile-target">4.14.1. Profiling on the Target</a></span></dt><dt><span class="section"><a href="#platdev-oprofile-oprofileui">4.14.2. Using OProfileUI</a></span></dt></dl></dd></dl></div><p> - This chapter describes standard tasks such as adding new - software packages, extending or customizing images, and porting work to - new hardware (adding a new machine). - The chapter also describes how to combine multiple - versions of library files into a single image, how to handle a package name alias, and - gives advice about how to make changes to the Yocto Project to achieve the best results. - </p><div class="section" title="4.1. Understanding and Creating Layers"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="understanding-and-creating-layers"></a>4.1. Understanding and Creating Layers</h2></div></div></div><p> - The OpenEmbedded build system supports organizing <a class="link" href="#metadata">metadata</a> - into multiple layers. - Layers allow you to isolate different types of customizations from each other. - You might find it tempting to keep everything in one layer when working on a single project. - However, the more modular you organize your metadata, the easier it is to cope with future changes. - </p><p> - To illustrate how layers are used to keep things modular, consider machine customizations. - These types of customizations typically reside in a BSP Layer. - Furthermore, the machine customizations should be isolated from recipes and metadata that support - a new GUI environment, for example. - This situation gives you a couple a layers: one for the machine configurations, and one for the - GUI environment. - It is important to understand, however, that the BSP layer can still make machine-specific - additions to recipes within the GUI environment layer without polluting the GUI layer itself - with those machine-specific changes. - You can accomplish this through a recipe that is a BitBake append - (<code class="filename">.bbappend</code>) file, which is described later in this section. - </p><p> - </p><div class="section" title="4.1.1. Layers"><div class="titlepage"><div><div><h3 class="title"><a id="yocto-project-layers"></a>4.1.1. Layers</h3></div></div></div><p> - The source directory contains several layers right out of the box. - You can easily identify a layer in the source directory by its folder name. - Folders that are layers begin with the string <code class="filename">meta</code>. - For example, when you set up the <a class="link" href="#source-directory">source directory</a> - structure, you will see several layers: <code class="filename">meta</code>, <code class="filename">meta-demoapps</code>, - <code class="filename">meta-skeleton</code>, and <code class="filename">meta-yocto</code>. - Each of these folders is a layer. - </p><p> - Furthermore, if you set up a local copy of the <code class="filename">meta-intel</code> Git repository - and then explore that folder, you will discover many BSP layers within the - <code class="filename">meta-intel</code> layer. - For more information on BSP layers, see the - "<a class="link" href="#bsp-layers" target="_top">BSP Layers</a>" - section in the Yocto Project Board Support Package (BSP) Developer's Guide. - </p></div><div class="section" title="4.1.2. Creating Your Own Layer"><div class="titlepage"><div><div><h3 class="title"><a id="creating-your-own-layer"></a>4.1.2. Creating Your Own Layer</h3></div></div></div><p> - It is very easy to create your own layer to use with the OpenEmbedded build system. - Follow these general steps to create your layer: - </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p><span class="emphasis"><em>Check Existing Layers:</em></span> Before creating a new layer, - you should be sure someone has not already created a layer containing the metadata - you need. - You can see the - <a class="ulink" href="http://www.openembedded.org/wiki/LayerIndex" target="_top"><code class="filename">LayerIndex</code></a> - for a list of layers from the OpenEmbedded community that can be used in the - Yocto Project.</p></li><li class="listitem"><p><span class="emphasis"><em>Create a Directory:</em></span> Create the directory - for your layer. - Traditionally, prepend the name of the folder with the string - <code class="filename">meta</code>. - For example: - </p><pre class="literallayout"> - meta-mylayer - meta-GUI_xyz - meta-mymachine - </pre></li><li class="listitem"><p><span class="emphasis"><em>Create a Layer Configuration File:</em></span> Inside your new - layer folder, you need to create a <code class="filename">conf/layer.conf</code> file. - It is easiest to take an existing layer configuration file and copy that to your - layer's <code class="filename">conf</code> directory and then modify the file as needed.</p><p>The <code class="filename">meta-yocto/conf/layer.conf</code> file demonstrates the - required syntax: - </p><pre class="literallayout"> - # We have a conf and classes directory, add to BBPATH - BBPATH := "${LAYERDIR}:${BBPATH}" - - # We have recipes-* directories, add to BBFILES - BBFILES := "${BBFILES} ${LAYERDIR}/recipes-*/*/*.bb \ - ${LAYERDIR}/recipes-*/*/*.bbappend" - - BBFILE_COLLECTIONS += "yocto" - BBFILE_PATTERN_yocto := "^${LAYERDIR}/" - BBFILE_PRIORITY_yocto = "5" - </pre><p>In the previous example, the recipes for the layers are added to - <code class="filename"><a class="link" href="#var-BBFILES" target="_top">BBFILES</a></code>. - The - <code class="filename"><a class="link" href="#var-BBFILE_COLLECTIONS" target="_top">BBFILE_COLLECTIONS</a></code> - variable is then appended with the layer name. - The - <code class="filename"><a class="link" href="#var-BBFILE_PATTERN" target="_top">BBFILE_PATTERN</a></code> - variable is set to a regular expression and is used to match files - from <code class="filename">BBFILES</code> into a particular layer. - In this case, immediate expansion of - <code class="filename"><a class="link" href="#var-LAYERDIR" target="_top">LAYERDIR</a></code> - sets <code class="filename">BBFILE_PATTERN</code> to the layer's path. - The - <code class="filename"><a class="link" href="#var-BBFILE_PRIORITY" target="_top">BBFILE_PRIORITY</a></code> - variable then assigns a priority to the layer. - Applying priorities is useful in situations where the same package might appear in multiple - layers and allows you to choose what layer should take precedence.</p><p>Note the use of the - <code class="filename"><a class="link" href="#var-LAYERDIR" target="_top">LAYERDIR</a></code> - variable with the immediate expansion operator. - The <code class="filename">LAYERDIR</code> variable expands to the directory of the current layer and - requires the immediate expansion operator so that BitBake does not wait to expand the variable - when it's parsing a different directory.</p><p>Through the use of the <code class="filename">BBPATH</code> variable, - BitBake locates <code class="filename">.bbclass</code> files, configuration - files, and files that are included with <code class="filename">include</code> - and <code class="filename">require</code> statements. - For these cases, BitBake uses the first file with the matching name found in - <code class="filename">BBPATH</code>. - This is similar to the way the <code class="filename">PATH</code> variable is used for binaries. - We recommend, therefore, that you use unique <code class="filename">.bbclass</code> - and configuration file names in your custom layer.</p></li><li class="listitem"><p><span class="emphasis"><em>Add Content:</em></span> Depending on the type of layer, - add the content. - If the layer adds support for a machine, add the machine configuration in - a <code class="filename">conf/machine/</code> file within the layer. - If the layer adds distro policy, add the distro configuration in a - <code class="filename">conf/distro/</code> file with the layer. - If the layer introduces new recipes, put the recipes you need in - <code class="filename">recipes-*</code> subdirectories within the layer.</p></li></ol></div><p> - </p><p> - To create layers that are easier to maintain, you should consider the following: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>Avoid "overlaying" entire recipes from other layers in your - configuration. - In other words, don't copy an entire recipe into your layer and then modify it. - Use <code class="filename">.bbappend</code> files to override the parts of the - recipe you need to modify.</p></li><li class="listitem"><p>Avoid duplicating include files. - Use <code class="filename">.bbappend</code> files for each recipe that uses an include - file. - Or, if you are introducing a new recipe that requires the included file, use the - path relative to the original layer directory to refer to the file. - For example, use <code class="filename">require recipes-core/somepackage/somefile.inc</code> - instead of <code class="filename">require somefile.inc</code>. - If you're finding you have to overlay the include file, it could indicate a - deficiency in the include file in the layer to which it originally belongs. - If this is the case, you need to address that deficiency instead of overlaying - the include file. - For example, consider how Qt 4 database support plugins are configured. - The source directory does not have - MySQL or PostgreSQL, however OpenEmbedded's - layer <code class="filename">meta-oe</code> does. - Consequently, <code class="filename">meta-oe</code> uses <code class="filename">.bbappend</code> - files to modify the <code class="filename">QT_SQL_DRIVER_FLAGS</code> variable to enable - the appropriate plugins. - This variable was added to the <code class="filename">qt4.inc</code> include file in - the source directory specifically to allow the <code class="filename">meta-oe</code> layer - to be able to control which plugins are built.</p></li></ul></div><p> - </p><p> - We also recommend the following: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>Store custom layers in a Git repository that uses the - <code class="filename">meta-<layer_name></code> format.</p></li><li class="listitem"><p>Clone the repository alongside other <code class="filename">meta</code> - directories in the - <a class="link" href="#source-directory">source directory</a>.</p></li></ul></div><p> - Following these recommendations keeps your source directory and - its configuration entirely inside the Yocto Project's core base. - </p></div><div class="section" title="4.1.3. Enabling Your Layer"><div class="titlepage"><div><div><h3 class="title"><a id="enabling-your-layer"></a>4.1.3. Enabling Your Layer</h3></div></div></div><p> - Before the OpenEmbedded build system can use your new layer, you need to enable it. - To enable your layer, simply add your layer's path to the - <code class="filename"><a class="link" href="#var-BBLAYERS" target="_top">BBLAYERS</a></code> - variable in your <code class="filename">conf/bblayers.conf</code> file, which is found in the - <a class="link" href="#build-directory">build directory</a>. - The following example shows how to enable a layer named <code class="filename">meta-mylayer</code>: - </p><pre class="literallayout"> - LCONF_VERSION = "1" - - BBFILES ?= "" - BBLAYERS = " \ - /path/to/poky/meta \ - /path/to/poky/meta-yocto \ - /path/to/poky/meta-mylayer \ - " - </pre><p> - </p><p> - BitBake parses each <code class="filename">conf/layer.conf</code> file as specified in the - <code class="filename">BBLAYERS</code> variable within the <code class="filename">conf/bblayers.conf</code> - file. - During the processing of each <code class="filename">conf/layer.conf</code> file, BitBake adds the - recipes, classes and configurations contained within the particular layer to the source - directory. - </p></div><div class="section" title="4.1.4. Using .bbappend Files"><div class="titlepage"><div><div><h3 class="title"><a id="using-bbappend-files"></a>4.1.4. Using .bbappend Files</h3></div></div></div><p> - Recipes used to append metadata to other recipes are called BitBake append files. - BitBake append files use the <code class="filename">.bbappend</code> file type suffix, while - underlying recipes to which metadata is being appended use the - <code class="filename">.bb</code> file type suffix. - </p><p> - A <code class="filename">.bbappend</code> file allows your layer to make additions or - changes to the content of another layer's recipe without having to copy the other - recipe into your layer. - Your <code class="filename">.bbappend</code> file resides in your layer, while the underlying - <code class="filename">.bb</code> recipe file to which you are appending metadata - resides in a different layer. - </p><p> - Append files files must have the same name as the underlying recipe. - For example, the append file <code class="filename">someapp_1.3.bbappend</code> must - apply to <code class="filename">someapp_1.3.bb</code>. - This means the original recipe and append file names are version number specific. - If the underlying recipe is renamed to update to a newer version, the - corresponding <code class="filename">.bbappend</code> file must be renamed as well. - During the build process, BitBake displays an error on starting if it detects a - <code class="filename">.bbappend</code> file that does not have an underlying recipe - with a matching name. - </p><p> - Being able to append information to an existing recipe not only avoids duplication, - but also automatically applies recipe changes in a different layer to your layer. - If you were copying recipes, you would have to manually merge changes as they occur. - </p><p> - As an example, consider the main formfactor recipe and a corresponding formfactor - append file both from the - <a class="link" href="#source-directory">source directory</a>. - Here is the main formfactor recipe, which is named <code class="filename">formfactor_0.0.bb</code> and - located in the meta layer at <code class="filename">meta/recipes-bsp/formfactor</code>: - </p><pre class="literallayout"> - DESCRIPTION = "Device formfactor information" - SECTION = "base" - LICENSE = "MIT" - LIC_FILES_CHKSUM = "file://${COREBASE}/LICENSE;md5=3f40d7994397109285ec7b81fdeb3b58 \ - file://${COREBASE}/meta/COPYING.MIT;md5=3da9cfbcb788c80a0384361b4de20420" - PR = "r20" - - SRC_URI = "file://config file://machconfig" - S = "${WORKDIR}" - - PACKAGE_ARCH = "${MACHINE_ARCH}" - INHIBIT_DEFAULT_DEPS = "1" - - do_install() { - # Only install file if it has a contents - install -d ${D}${sysconfdir}/formfactor/ - install -m 0644 ${S}/config ${D}${sysconfdir}/formfactor/ - if [ -s "${S}/machconfig" ]; then - install -m 0644 ${S}/machconfig ${D}${sysconfdir}/formfactor/ - fi - } - </pre><p> - Here is the append file, which is named <code class="filename">formfactor_0.0.bbappend</code> and is from the - Crown Bay BSP Layer named <code class="filename">meta-intel/meta-crownbay</code>. - The file is in <code class="filename">recipes-bsp/formfactor</code>: - </p><pre class="literallayout"> - FILESEXTRAPATHS_prepend := "${THISDIR}/${PN}:" - - PRINC = "1" - </pre><p> - This example adds or overrides files in - <a class="link" href="#var-SRC_URI" target="_top"><code class="filename">SRC_URI</code></a> - within a <code class="filename">.bbappend</code> by extending the path BitBake uses to search for files. - The most reliable way to do this is by prepending the - <code class="filename">FILESEXTRAPATHS</code> variable. - For example, if you have your files in a directory that is named the same as your package - (<a class="link" href="#var-PN" target="_top"><code class="filename">PN</code></a>), - you can add this directory by adding the following to your <code class="filename">.bbappend</code> file: - </p><pre class="literallayout"> - FILESEXTRAPATHS_prepend := "${THISDIR}/${PN}:" - </pre><p> - Using the immediate expansion assignment operator <code class="filename">:=</code> is important because - of the reference to <code class="filename">THISDIR</code>. - The trailing colon character is important as it ensures that items in the list remain - colon-separated. - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>BitBake automatically defines the <code class="filename">THISDIR</code> variable. - You should never set this variable yourself. - Using <code class="filename">_prepend</code> ensures your path will be searched prior to other - paths in the final list. - </div><p> - </p><p> - For another example on how to use a <code class="filename">.bbappend</code> file, see the - "<a class="link" href="#changing-recipes-kernel" title="A.5.2.4. Changing recipes-kernel">Changing <code class="filename">recipes-kernel</code></a>" - section. - </p></div><div class="section" title="4.1.5. Prioritizing Your Layer"><div class="titlepage"><div><div><h3 class="title"><a id="prioritizing-your-layer"></a>4.1.5. Prioritizing Your Layer</h3></div></div></div><p> - Each layer is assigned a priority value. - Priority values control which layer takes precedence if there are recipe files with - the same name in multiple layers. - For these cases, the recipe file from the layer with a higher priority number taking precedence. - Priority values also affect the order in which multiple <code class="filename">.bbappend</code> files - for the same recipe are applied. - You can either specify the priority manually, or allow the build system to calculate it - based on the layer's dependencies. - </p><p> - To specify the layer's priority manually, use the - <a class="link" href="#var-BBFILE_PRIORITY" target="_top"><code class="filename">BBFILE_PRIORITY</code></a> - variable. - For example: - </p><pre class="literallayout"> - BBFILE_PRIORITY := "1" - </pre><p> - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>It is possible for a recipe with a lower version number - <a class="link" href="#var-PV" target="_top"><code class="filename">PV</code></a> - in a layer that has a higher priority to take precedence.</p><p>Also, the layer priority does not currently affect the precedence order of - <code class="filename">.conf</code> or <code class="filename">.bbclass</code> files. - Future versions of BitBake might address this.</p></div></div><div class="section" title="4.1.6. Managing Layers"><div class="titlepage"><div><div><h3 class="title"><a id="managing-layers"></a>4.1.6. Managing Layers</h3></div></div></div><p> - You can use the BitBake layer management tool to provide a view into the structure of - recipes across a multi-layer project. - Being able to generate output that reports on configured layers with their paths and - priorities and on <code class="filename">.bbappend</code> files and their applicable recipes - can help to reveal potential problems. - </p><p> - Use the following form when running the layer management tool. - </p><pre class="literallayout"> - $ bitbake-layers <command> [arguments] - </pre><p> - The following list describes the available commands: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><code class="filename"><span class="emphasis"><em>help:</em></span></code> - Displays general help or help on a specified command.</p></li><li class="listitem"><p><code class="filename"><span class="emphasis"><em>show-layers:</em></span></code> - Show the current configured layers.</p></li><li class="listitem"><p><code class="filename"><span class="emphasis"><em>show-recipes:</em></span></code> - Lists available recipes and the layers that provide them. - </p></li><li class="listitem"><p><code class="filename"><span class="emphasis"><em>show-overlayed:</em></span></code> - Lists overlayed recipes. - A recipe is overlayed when a recipe with the same name exists in another layer - that has a higher layer priority. - </p></li><li class="listitem"><p><code class="filename"><span class="emphasis"><em>show-appends:</em></span></code> - Lists <code class="filename">.bbappend</code> files and the recipe files to which - they apply.</p></li><li class="listitem"><p><code class="filename"><span class="emphasis"><em>flatten:</em></span></code> - Flattens the layer configuration into a separate output directory. - Flattening your layer configuration builds a "flattened" directory that contains - the contents of all layers, with any overlayed recipes removed and any - <code class="filename">.bbappend</code> files appended to the corresponding recipes. - You might have to perform some manual cleanup of the flattened layer as follows: - </p><div class="itemizedlist"><ul class="itemizedlist" type="circle"><li class="listitem"><p>Non-recipe files (such as patches) are overwritten. - The flatten command shows a warning for these files.</p></li><li class="listitem"><p>Anything beyond the normal layer setup has been added to - the <code class="filename">layer.conf</code> file. - Only the lowest priority layer's <code class="filename">layer.conf</code> is used. - </p></li><li class="listitem"><p>Overridden and appended items from <code class="filename">.bbappend</code> - files need to be cleaned up. - The contents of each <code class="filename">.bbappend</code> end up in the - flattened recipe. - However, if there are appended or changed variable values, you need to tidy - these up yourself. - Consider the following example. - Here, the <code class="filename">bitbake-layers</code> command adds the line - <code class="filename">#### bbappended ...</code> so that you know where the following - lines originate: - </p><pre class="literallayout"> - ... - DESCRIPTION = "A useful utility" - ... - EXTRA_OECONF = "--enable-something" - ... - - #### bbappended from meta-anotherlayer #### - - DESCRIPTION = "Customized utility" - EXTRA_OECONF += "--enable-somethingelse" - </pre><p> - Ideally, you would tidy up these utilities as follows: - </p><pre class="literallayout"> - ... - DESCRIPTION = "Customized utility" - ... - EXTRA_OECONF = "--enable-something --enable-somethingelse" - ... - </pre></li></ul></div></li></ul></div><p> - </p></div></div><div class="section" title="4.2. Customizing Images"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="usingpoky-extend-customimage"></a>4.2. Customizing Images</h2></div></div></div><p> - You can customize images to satisfy particular requirements. - This section describes several methods and provides guidelines for each. - </p><div class="section" title="4.2.1. Customizing Images Using Custom .bb Files"><div class="titlepage"><div><div><h3 class="title"><a id="usingpoky-extend-customimage-custombb"></a>4.2.1. Customizing Images Using Custom .bb Files</h3></div></div></div><p> - One way to get additional software into an image is to create a custom image. - The following example shows the form for the two lines you need: - </p><pre class="literallayout"> - IMAGE_INSTALL = "task-core-x11-base package1 package2" - - inherit core-image - </pre><p> - </p><p> - By creating a custom image, a developer has total control - over the contents of the image. - It is important to use the correct names of packages in the - <code class="filename"><a class="link" href="#var-IMAGE_INSTALL" target="_top">IMAGE_INSTALL</a></code> - variable. - You must use the OpenEmbedded notation and not the Debian notation for the names - (e.g. <code class="filename">eglibc-dev</code> instead of <code class="filename">libc6-dev</code>). - </p><p> - The other method for creating a custom image is to base it on an existing image. - For example, if you want to create an image based on <code class="filename">core-image-sato</code> - but add the additional package <code class="filename">strace</code> to the image, - copy the <code class="filename">meta/recipes-sato/images/core-image-sato.bb</code> to a - new <code class="filename">.bb</code> and add the following line to the end of the copy: - </p><pre class="literallayout"> - IMAGE_INSTALL += "strace" - </pre><p> - </p></div><div class="section" title="4.2.2. Customizing Images Using Custom Tasks"><div class="titlepage"><div><div><h3 class="title"><a id="usingpoky-extend-customimage-customtasks"></a>4.2.2. Customizing Images Using Custom Tasks</h3></div></div></div><p> - For complex custom images, the best approach is to create a custom task package - that is used to build the image or images. - A good example of a tasks package is - <code class="filename">meta/recipes-core/tasks/task-core-boot.bb</code> - The - <code class="filename"><a class="link" href="#var-PACKAGES" target="_top">PACKAGES</a></code> - variable lists the task packages to build along with the complementary - <code class="filename">-dbg</code> and <code class="filename">-dev</code> packages. - For each package added, you can use - <code class="filename"><a class="link" href="#var-RDEPENDS" target="_top">RDEPENDS</a></code> - and - <code class="filename"><a class="link" href="#var-RRECOMMENDS" target="_top">RRECOMMENDS</a></code> - entries to provide a list of packages the parent task package should contain. - Following is an example: - </p><pre class="literallayout"> - DESCRIPTION = "My Custom Tasks" - - PACKAGES = "\ - task-custom-apps \ - task-custom-apps-dbg \ - task-custom-apps-dev \ - task-custom-tools \ - task-custom-tools-dbg \ - task-custom-tools-dev \ - " - - RDEPENDS_task-custom-apps = "\ - dropbear \ - portmap \ - psplash" - - RDEPENDS_task-custom-tools = "\ - oprofile \ - oprofileui-server \ - lttng-control \ - lttng-viewer" - - RRECOMMENDS_task-custom-tools = "\ - kernel-module-oprofile" - </pre><p> - </p><p> - In the previous example, two task packages are created with their dependencies and their - recommended package dependencies listed: <code class="filename">task-custom-apps</code>, and - <code class="filename">task-custom-tools</code>. - To build an image using these task packages, you need to add - <code class="filename">task-custom-apps</code> and/or - <code class="filename">task-custom-tools</code> to - <code class="filename"><a class="link" href="#var-IMAGE_INSTALL" target="_top">IMAGE_INSTALL</a></code>. - For other forms of image dependencies see the other areas of this section. - </p></div><div class="section" title="4.2.3. Customizing Images Using Custom IMAGE_FEATURES and EXTRA_IMAGE_FEATURES"><div class="titlepage"><div><div><h3 class="title"><a id="usingpoky-extend-customimage-imagefeatures"></a>4.2.3. Customizing Images Using Custom <code class="filename">IMAGE_FEATURES</code> and - <code class="filename">EXTRA_IMAGE_FEATURES</code></h3></div></div></div><p> - Ultimately users might want to add extra image features to the set by using the - <code class="filename"><a class="link" href="#var-IMAGE_FEATURES" target="_top">IMAGE_FEATURES</a></code> - variable. - To create these features, the best reference is - <code class="filename">meta/classes/core-image.bbclass</code>, which shows how to achieve this. - In summary, the file looks at the contents of the - <code class="filename">IMAGE_FEATURES</code> - variable and then maps that into a set of tasks or packages. - Based on this information the - <code class="filename"><a class="link" href="#var-IMAGE_INSTALL" target="_top"> IMAGE_INSTALL</a></code> - variable is generated automatically. - Users can add extra features by extending the class or creating a custom class for use - with specialized image <code class="filename">.bb</code> files. - You can also add more features by configuring the - <code class="filename"><a class="link" href="#var-EXTRA_IMAGE_FEATURES" target="_top">EXTRA_IMAGE_FEATURES</a></code> - variable in the <code class="filename">local.conf</code> file found in the source directory - located in the build directory. - </p><p> - The Yocto Project ships with two SSH servers you can use in your images: - Dropbear and OpenSSH. - Dropbear is a minimal SSH server appropriate for resource-constrained environments, - while OpenSSH is a well-known standard SSH server implementation. - By default, the <code class="filename">core-image-sato</code> image is configured to use Dropbear. - The <code class="filename">core-image-basic</code> and <code class="filename">core-image-lsb</code> - images both include OpenSSH. - The <code class="filename">core-image-minimal</code> image does not contain an SSH server. - To change these defaults, edit the <code class="filename">IMAGE_FEATURES</code> variable - so that it sets the image you are working with to include - <code class="filename">ssh-server-dropbear</code> or <code class="filename">ssh-server-openssh</code>. - </p></div><div class="section" title="4.2.4. Customizing Images Using local.conf"><div class="titlepage"><div><div><h3 class="title"><a id="usingpoky-extend-customimage-localconf"></a>4.2.4. Customizing Images Using <code class="filename">local.conf</code></h3></div></div></div><p> - It is possible to customize image contents by using variables from your - local configuration in your <code class="filename">conf/local.conf</code> file. - Because it is limited to local use, this method generally only allows you to - add packages and is not as flexible as creating your own customized image. - When you add packages using local variables this way, you need to realize that - these variable changes affect all images at the same time and might not be - what you require. - </p><p> - The simplest way to add extra packages to all images is by using the - <code class="filename"><a class="link" href="#var-IMAGE_INSTALL" target="_top">IMAGE_INSTALL</a></code> - variable with the <code class="filename">_append</code> operator: - </p><pre class="literallayout"> - IMAGE_INSTALL_append = " strace" - </pre><p> - Use of the syntax is important. - Specifically, the space between the quote and the package name, which is - <code class="filename">strace</code> in this example. - This space is required since the <code class="filename">_append</code> - operator does not add the space. - </p><p> - Furthermore, you must use <code class="filename">_append</code> instead of the <code class="filename">+=</code> - operator if you want to avoid ordering issues. - The reason for this is because doing so unconditionally appends to the variable and - avoids ordering problems due to the variable being set in image recipes and - <code class="filename">.bbclass</code> files with operators like <code class="filename">?=</code>. - Using <code class="filename">_append</code> ensures the operation takes affect. - </p><p> - As shown in its simplest use, <code class="filename">IMAGE_INSTALL_append</code> affects - all images. - It is possible to extend the syntax so that the variable applies to a specific image only. - Here is an example: - </p><pre class="literallayout"> - IMAGE_INSTALL_append_pn-core-image-minimal = " strace" - </pre><p> - This example adds <code class="filename">strace</code> to <code class="filename">core-image-minimal</code> - only. - </p><p> - You can add packages using a similar approach through the - <code class="filename"><a class="link" href="#var-CORE_IMAGE_EXTRA_INSTALL" target="_top">CORE_IMAGE_EXTRA_INSTALL</a></code> - variable. - If you use this variable, only <code class="filename">core-image-*</code> images are affected. - </p></div></div><div class="section" title="4.3. Adding a Package"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="usingpoky-extend-addpkg"></a>4.3. Adding a Package</h2></div></div></div><p> - To add a package you need to write a recipe for it. - Writing a recipe means creating a <code class="filename">.bb</code> file that sets some - variables. - For information on variables that are useful for recipes and for information about recipe naming - issues, see the - "<a class="link" href="#ref-varlocality-recipe-required" target="_top">Required</a>" - section of the Yocto Project Reference Manual. - </p><p> - Before writing a recipe from scratch, it is often useful to check - whether someone else has written one already. - OpenEmbedded is a good place to look as it has a wider scope and range of packages. - Because the Yocto Project aims to be compatible with OpenEmbedded, most recipes - you find there should work for you. - </p><p> - For new packages, the simplest way to add a recipe is to base it on a similar - pre-existing recipe. - The sections that follow provide some examples that show how to add standard - types of packages. - </p><div class="section" title="4.3.1. Single .c File Package (Hello World!)"><div class="titlepage"><div><div><h3 class="title"><a id="usingpoky-extend-addpkg-singlec"></a>4.3.1. Single .c File Package (Hello World!)</h3></div></div></div><p> - Building an application from a single file that is stored locally (e.g. under - <code class="filename">files/</code>) requires a recipe that has the file listed in - the - <code class="filename"><a class="link" href="#var-SRC_URI" target="_top">SRC_URI</a></code> - variable. - Additionally, you need to manually write the <code class="filename">do_compile</code> and - <code class="filename">do_install</code> tasks. - The <code class="filename"><a class="link" href="#var-S" target="_top">S</a></code> - variable defines the - directory containing the source code, which is set to - <code class="filename"><a class="link" href="#var-WORKDIR" target="_top"> - WORKDIR</a></code> in this case - the directory BitBake uses for the build. - </p><pre class="literallayout"> - DESCRIPTION = "Simple helloworld application" - SECTION = "examples" - LICENSE = "MIT" - LIC_FILES_CHKSUM = "file://${COMMON_LICENSE_DIR}/MIT;md5=0835ade698e0bcf8506ecda2f7b4f302" - PR = "r0" - - SRC_URI = "file://helloworld.c" - - S = "${WORKDIR}" - - do_compile() { - ${CC} helloworld.c -o helloworld - } - - do_install() { - install -d ${D}${bindir} - install -m 0755 helloworld ${D}${bindir} - } - </pre><p> - </p><p> - By default, the <code class="filename">helloworld</code>, <code class="filename">helloworld-dbg</code>, - and <code class="filename">helloworld-dev</code> packages are built. - For information on how to customize the packaging process, see the - "<a class="link" href="#splitting-an-application-into-multiple-packages" title="4.3.4. Splitting an Application into Multiple Packages">Splitting an Application - into Multiple Packages</a>" section. - </p></div><div class="section" title="4.3.2. Autotooled Package"><div class="titlepage"><div><div><h3 class="title"><a id="usingpoky-extend-addpkg-autotools"></a>4.3.2. Autotooled Package</h3></div></div></div><p> - Applications that use Autotools such as <code class="filename">autoconf</code> and - <code class="filename">automake</code> require a recipe that has a source archive listed in - <code class="filename"><a class="link" href="#var-SRC_URI" target="_top">SRC_URI</a></code> and - also inherits Autotools, which instructs BitBake to use the - <code class="filename">autotools.bbclass</code> file, which contains the definitions of all the steps - needed to build an Autotool-based application. - The result of the build is automatically packaged. - And, if the application uses NLS for localization, packages with local information are - generated (one package per language). - Following is one example: (<code class="filename">hello_2.3.bb</code>) - </p><pre class="literallayout"> - DESCRIPTION = "GNU Helloworld application" - SECTION = "examples" - LICENSE = "GPLv2+" - LIC_FILES_CHKSUM = "file://COPYING;md5=751419260aa954499f7abaabaa882bbe" - PR = "r0" - - SRC_URI = "${GNU_MIRROR}/hello/hello-${PV}.tar.gz" - - inherit autotools gettext - </pre><p> - </p><p> - The variable - <code class="filename"><a class="link" href="#var-LIC_FILES_CHKSUM" target="_top">LIC_FILES_CHKSUM</a></code> - is used to track source license changes as described in the - "<a class="link" href="#usingpoky-configuring-LIC_FILES_CHKSUM" target="_top">Track License Changes</a>" section. - You can quickly create Autotool-based recipes in a manner similar to the previous example. - </p></div><div class="section" title="4.3.3. Makefile-Based Package"><div class="titlepage"><div><div><h3 class="title"><a id="usingpoky-extend-addpkg-makefile"></a>4.3.3. Makefile-Based Package</h3></div></div></div><p> - Applications that use GNU <code class="filename">make</code> also require a recipe that has - the source archive listed in - <code class="filename"><a class="link" href="#var-SRC_URI" target="_top">SRC_URI</a></code>. - You do not need to add a <code class="filename">do_compile</code> step since by default BitBake - starts the <code class="filename">make</code> command to compile the application. - If you need additional <code class="filename">make</code> options you should store them in the - <code class="filename"><a class="link" href="#var-EXTRA_OEMAKE" target="_top">EXTRA_OEMAKE</a></code> - variable. - BitBake passes these options into the <code class="filename">make</code> GNU invocation. - Note that a <code class="filename">do_install</code> task is still required. - Otherwise BitBake runs an empty <code class="filename">do_install</code> task by default. - </p><p> - Some applications might require extra parameters to be passed to the compiler. - For example, the application might need an additional header path. - You can accomplish this by adding to the - <code class="filename"><a class="link" href="#var-CFLAGS" target="_top">CFLAGS</a></code> variable. - The following example shows this: - </p><pre class="literallayout"> - CFLAGS_prepend = "-I ${S}/include " - </pre><p> - </p><p> - In the following example, <code class="filename">mtd-utils</code> is a makefile-based package: - </p><pre class="literallayout"> - DESCRIPTION = "Tools for managing memory technology devices." - SECTION = "base" - DEPENDS = "zlib lzo e2fsprogs util-linux" - HOMEPAGE = "http://www.linux-mtd.infradead.org/" - LICENSE = "GPLv2+" - LIC_FILES_CHKSUM = "file://COPYING;md5=0636e73ff0215e8d672dc4c32c317bb3 \ - file://include/common.h;beginline=1;endline=17;md5=ba05b07912a44ea2bf81ce409380049c" - - SRC_URI = "git://git.infradead.org/mtd-utils.git;protocol=git;tag=995cfe51b0a3cf32f381c140bf72b21bf91cef1b \ - file://add-exclusion-to-mkfs-jffs2-git-2.patch" - - S = "${WORKDIR}/git/" - - PR = "r1" - - EXTRA_OEMAKE = "'CC=${CC}' 'RANLIB=${RANLIB}' 'AR=${AR}' \ - 'CFLAGS=${CFLAGS} -I${S}/include -DWITHOUT_XATTR' 'BUILDDIR=${S}'" - - do_install () { - oe_runmake install DESTDIR=${D} SBINDIR=${sbindir} MANDIR=${mandir} \ - INCLUDEDIR=${includedir} - install -d ${D}${includedir}/mtd/ - for f in ${S}/include/mtd/*.h; do - install -m 0644 $f ${D}${includedir}/mtd/ - done - } - - PARALLEL_MAKE = "" - - BBCLASSEXTEND = "native" - </pre><p> - </p><p> - If your sources are available as a tarball instead of a Git repository, you - will need to provide the URL to the tarball as well as an - <code class="filename">md5</code> or <code class="filename">sha256</code> sum of - the download. - Here is an example: - </p><pre class="literallayout"> - SRC_URI="ftp://ftp.infradead.org/pub/mtd-utils/mtd-utils-1.4.9.tar.bz2" - SRC_URI[md5sum]="82b8e714b90674896570968f70ca778b" - </pre><p> - You can generate the <code class="filename">md5</code> or <code class="filename">sha256</code> sums - by using the <code class="filename">md5sum</code> or <code class="filename">sha256sum</code> commands - with the target file as the only argument. - Here is an example: - </p><pre class="literallayout"> - $ md5sum mtd-utils-1.4.9.tar.bz2 - 82b8e714b90674896570968f70ca778b mtd-utils-1.4.9.tar.bz2 - </pre><p> - </p></div><div class="section" title="4.3.4. Splitting an Application into Multiple Packages"><div class="titlepage"><div><div><h3 class="title"><a id="splitting-an-application-into-multiple-packages"></a>4.3.4. Splitting an Application into Multiple Packages</h3></div></div></div><p> - You can use the variables - <code class="filename"><a class="link" href="#var-PACKAGES" target="_top">PACKAGES</a></code> and - <code class="filename"><a class="link" href="#var-FILES" target="_top">FILES</a></code> - to split an application into multiple packages. - </p><p> - Following is an example that uses the <code class="filename">libXpm</code> recipe. - By default, this recipe generates a single package that contains the library along - with a few binaries. - You can modify the recipe to split the binaries into separate packages: - </p><pre class="literallayout"> - require xorg-lib-common.inc - - DESCRIPTION = "X11 Pixmap library" - LICENSE = "X-BSD" - LIC_FILES_CHKSUM = "file://COPYING;md5=3e07763d16963c3af12db271a31abaa5" - DEPENDS += "libxext libsm libxt" - PR = "r3" - PE = "1" - - XORG_PN = "libXpm" - - PACKAGES =+ "sxpm cxpm" - FILES_cxpm = "${bindir}/cxpm" - FILES_sxpm = "${bindir}/sxpm" - </pre><p> - </p><p> - In the previous example, we want to ship the <code class="filename">sxpm</code> - and <code class="filename">cxpm</code> binaries in separate packages. - Since <code class="filename">bindir</code> would be packaged into the main - <code class="filename"><a class="link" href="#var-PN" target="_top">PN</a></code> - package by default, we prepend the - <code class="filename"><a class="link" href="#var-PACKAGES" target="_top">PACKAGES</a> - </code> variable so additional package names are added to the start of list. - This results in the extra - <code class="filename"><a class="link" href="#var-FILES" target="_top">FILES</a>_*</code> - variables then containing information that define which files and - directories go into which packages. - Files included by earlier packages are skipped by latter packages. - Thus, the main - <code class="filename"><a class="link" href="#var-PN" target="_top">PN</a></code> package - does not include the above listed files. - </p></div><div class="section" title="4.3.5. Including Static Library Files"><div class="titlepage"><div><div><h3 class="title"><a id="including-static-library-files"></a>4.3.5. Including Static Library Files</h3></div></div></div><p> - If you are building a library and the library offers static linking, you can control - which static library files (<code class="filename">*.a</code> files) get included in the - built library. - </p><p> - The <code class="filename">PACKAGES</code> and <code class="filename">FILES_*</code> variables in the - <code class="filename">meta/conf/bitbake.conf</code> configuration file define how files installed - by the <code class="filename">do_install</code> task are packaged. - By default, the <code class="filename">PACKAGES</code> variable contains - <code class="filename">${PN}-staticdev</code>, which includes all static library files. - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3> - Previously released versions of the Yocto Project defined the static library files - through <code class="filename">${PN}-dev</code>. - </div><p> - Following, is part of the BitBake configuration file. - You can see where the static library files are defined: - </p><pre class="literallayout"> - PACKAGES = "${PN}-dbg ${PN} ${PN}-doc ${PN}-dev ${PN}-staticdev ${PN}-locale" - PACKAGES_DYNAMIC = "${PN}-locale-*" - FILES = "" - - FILES_${PN} = "${bindir}/* ${sbindir}/* ${libexecdir}/* ${libdir}/lib*${SOLIBS} \ - ${sysconfdir} ${sharedstatedir} ${localstatedir} \ - ${base_bindir}/* ${base_sbindir}/* \ - ${base_libdir}/*${SOLIBS} \ - ${datadir}/${BPN} ${libdir}/${BPN}/* \ - ${datadir}/pixmaps ${datadir}/applications \ - ${datadir}/idl ${datadir}/omf ${datadir}/sounds \ - ${libdir}/bonobo/servers" - - FILES_${PN}-doc = "${docdir} ${mandir} ${infodir} ${datadir}/gtk-doc \ - ${datadir}/gnome/help" - SECTION_${PN}-doc = "doc" - - FILES_${PN}-dev = "${includedir} ${libdir}/lib*${SOLIBSDEV} ${libdir}/*.la \ - ${libdir}/*.o ${libdir}/pkgconfig ${datadir}/pkgconfig \ - ${datadir}/aclocal ${base_libdir}/*.o" - SECTION_${PN}-dev = "devel" - ALLOW_EMPTY_${PN}-dev = "1" - RDEPENDS_${PN}-dev = "${PN} (= ${EXTENDPKGV})" - - FILES_${PN}-staticdev = "${libdir}/*.a ${base_libdir}/*.a" - SECTION_${PN}-staticdev = "devel" - RDEPENDS_${PN}-staticdev = "${PN}-dev (= ${EXTENDPKGV})" - </pre><p> - </p></div><div class="section" title="4.3.6. Post Install Scripts"><div class="titlepage"><div><div><h3 class="title"><a id="usingpoky-extend-addpkg-postinstalls"></a>4.3.6. Post Install Scripts</h3></div></div></div><p> - To add a post-installation script to a package, add a <code class="filename">pkg_postinst_PACKAGENAME() - </code> function to the <code class="filename">.bb</code> file and use - <code class="filename">PACKAGENAME</code> as the name of the package you want to attach to the - <code class="filename">postinst</code> script. - Normally - <code class="filename"><a class="link" href="#var-PN" target="_top">PN</a></code> - can be used, which automatically expands to <code class="filename">PACKAGENAME</code>. - A post-installation function has the following structure: - </p><pre class="literallayout"> - pkg_postinst_PACKAGENAME () { - #!/bin/sh -e - # Commands to carry out - } - </pre><p> - </p><p> - The script defined in the post-installation function is called when the - root filesystem is created. - If the script succeeds, the package is marked as installed. - If the script fails, the package is marked as unpacked and the script is - executed when the image boots again. - </p><p> - Sometimes it is necessary for the execution of a post-installation - script to be delayed until the first boot. - For example, the script might need to be executed on the device itself. - To delay script execution until boot time, use the following structure in the - post-installation script: - </p><pre class="literallayout"> - pkg_postinst_PACKAGENAME () { - #!/bin/sh -e - if [ x"$D" = "x" ]; then - # Actions to carry out on the device go here - else - exit 1 - fi - } - </pre><p> - </p><p> - The previous example delays execution until the image boots again because the - <code class="filename"><a class="link" href="#var-D" target="_top">D</a></code> - variable points - to the directory containing the image when the root filesystem is created at build time but - is unset when executed on the first boot. - </p></div></div><div class="section" title="4.4. Adding a New Machine"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="platdev-newmachine"></a>4.4. Adding a New Machine</h2></div></div></div><p> - Adding a new machine to the Yocto Project is a straightforward process. - This section provides information that gives you an idea of the changes you must make. - The information covers adding machines similar to those the Yocto Project already supports. - Although well within the capabilities of the Yocto Project, adding a totally new architecture - might require - changes to <code class="filename">gcc/eglibc</code> and to the site information, which is - beyond the scope of this manual. - </p><p> - For a complete example that shows how to add a new machine, - see the - "<a class="link" href="#dev-manual-bsp-appendix" target="_top">BSP Development Example</a>" - in Appendix A. - </p><div class="section" title="4.4.1. Adding the Machine Configuration File"><div class="titlepage"><div><div><h3 class="title"><a id="platdev-newmachine-conffile"></a>4.4.1. Adding the Machine Configuration File</h3></div></div></div><p> - To add a machine configuration you need to add a <code class="filename">.conf</code> file - with details of the device being added to the <code class="filename">conf/machine/</code> file. - The name of the file determines the name the OpenEmbedded build system - uses to reference the new machine. - </p><p> - The most important variables to set in this file are as follows: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><code class="filename"><a class="link" href="#var-TARGET_ARCH" target="_top"> - TARGET_ARCH</a></code> (e.g. "arm")</p></li><li class="listitem"><p><code class="filename"><a class="link" href="#var-PREFERRED_PROVIDER" target="_top"> - PREFERRED_PROVIDER</a></code>_virtual/kernel (see below)</p></li><li class="listitem"><p><code class="filename"><a class="link" href="#var-MACHINE_FEATURES" target="_top"> - MACHINE_FEATURES</a></code> (e.g. "apm screen wifi")</p></li></ul></div><p> - </p><p> - You might also need these variables: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><code class="filename"><a class="link" href="#var-SERIAL_CONSOLE" target="_top"> - SERIAL_CONSOLE</a></code> (e.g. "115200 ttyS0")</p></li><li class="listitem"><p><code class="filename"><a class="link" href="#var-KERNEL_IMAGETYPE" target="_top"> - KERNEL_IMAGETYPE</a></code> (e.g. "zImage")</p></li><li class="listitem"><p><code class="filename"><a class="link" href="#var-IMAGE_FSTYPES" target="_top"> - IMAGE_FSTYPES</a></code> (e.g. "tar.gz jffs2")</p></li></ul></div><p> - </p><p> - You can find full details on these variables in the reference section. - You can leverage many existing machine <code class="filename">.conf</code> files from - <code class="filename">meta/conf/machine/</code>. - </p></div><div class="section" title="4.4.2. Adding a Kernel for the Machine"><div class="titlepage"><div><div><h3 class="title"><a id="platdev-newmachine-kernel"></a>4.4.2. Adding a Kernel for the Machine</h3></div></div></div><p> - The OpenEmbedded build system needs to be able to build a kernel for the machine. - You need to either create a new kernel recipe for this machine, or extend an - existing recipe. - You can find several kernel examples in the - source directory at <code class="filename">meta/recipes-kernel/linux</code> - that you can use as references. - </p><p> - If you are creating a new recipe, normal recipe-writing rules apply for setting - up a - <code class="filename"><a class="link" href="#var-SRC_URI" target="_top">SRC_URI</a></code>. - Thus, you need to specify any necessary patches and set - <code class="filename"><a class="link" href="#var-S" target="_top">S</a></code> to point at the source code. - You need to create a <code class="filename">configure</code> task that configures the - unpacked kernel with a defconfig. - You can do this by using a <code class="filename">make defconfig</code> command or, - more commonly, by copying in a suitable <code class="filename">defconfig</code> file and and then running - <code class="filename">make oldconfig</code>. - By making use of <code class="filename">inherit kernel</code> and potentially some of the - <code class="filename">linux-*.inc</code> files, most other functionality is - centralized and the the defaults of the class normally work well. - </p><p> - If you are extending an existing kernel, it is usually a matter of adding a - suitable defconfig file. - The file needs to be added into a location similar to defconfig files - used for other machines in a given kernel. - A possible way to do this is by listing the file in the - <code class="filename">SRC_URI</code> and adding the machine to the expression in - <code class="filename"><a class="link" href="#var-COMPATIBLE_MACHINE" target="_top">COMPATIBLE_MACHINE</a></code>: - </p><pre class="literallayout"> - COMPATIBLE_MACHINE = '(qemux86|qemumips)' - </pre><p> - </p></div><div class="section" title="4.4.3. Adding a Formfactor Configuration File"><div class="titlepage"><div><div><h3 class="title"><a id="platdev-newmachine-formfactor"></a>4.4.3. Adding a Formfactor Configuration File</h3></div></div></div><p> - A formfactor configuration file provides information about the - target hardware for which the image is being built and information that - the build system cannot obtain from other sources such as the kernel. - Some examples of information contained in a formfactor configuration file include - framebuffer orientation, whether or not the system has a keyboard, - the positioning of the keyboard in relation to the screen, and - the screen resolution. - </p><p> - The build system uses reasonable defaults in most cases, but if customization is - necessary you need to create a <code class="filename">machconfig</code> file - in the <code class="filename">meta/recipes-bsp/formfactor/files</code> - directory. - This directory contains directories for specific machines such as - <code class="filename">qemuarm</code> and <code class="filename">qemux86</code>. - For information about the settings available and the defaults, see the - <code class="filename">meta/recipes-bsp/formfactor/files/config</code> file found in the - same area. - Following is an example for qemuarm: - </p><pre class="literallayout"> - HAVE_TOUCHSCREEN=1 - HAVE_KEYBOARD=1 - - DISPLAY_CAN_ROTATE=0 - DISPLAY_ORIENTATION=0 - #DISPLAY_WIDTH_PIXELS=640 - #DISPLAY_HEIGHT_PIXELS=480 - #DISPLAY_BPP=16 - DISPLAY_DPI=150 - DISPLAY_SUBPIXEL_ORDER=vrgb - </pre><p> - </p></div></div><div class="section" title="4.5. Combining Multiple Versions of Library Files into One Image"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="building-multiple-architecture-libraries-into-one-image"></a>4.5. Combining Multiple Versions of Library Files into One Image</h2></div></div></div><p> - The build system offers the ability to build libraries with different - target optimizations or architecture formats and combine these together - into one system image. - You can link different binaries in the image - against the different libraries as needed for specific use cases. - This feature is called "Multilib." - </p><p> - An example would be where you have most of a system compiled in 32-bit - mode using 32-bit libraries, but you have something large, like a database - engine, that needs to be a 64-bit application and use 64-bit libraries. - Multilib allows you to get the best of both 32-bit and 64-bit libraries. - </p><p> - While the Multilib feature is most commonly used for 32 and 64-bit differences, - the approach the build system uses facilitates different target optimizations. - You could compile some binaries to use one set of libraries and other binaries - to use other different sets of libraries. - The libraries could differ in architecture, compiler options, or other - optimizations. - </p><p> - This section overviews the Multilib process only. - For more details on how to implement Multilib, see the - <a class="ulink" href="https://wiki.yoctoproject.org/wiki/Multilib" target="_top">Multilib</a> wiki - page. - </p><div class="section" title="4.5.1. Preparing to use Multilib"><div class="titlepage"><div><div><h3 class="title"><a id="preparing-to-use-multilib"></a>4.5.1. Preparing to use Multilib</h3></div></div></div><p> - User-specific requirements drive the Multilib feature, - Consequently, there is no one "out-of-the-box" configuration that likely - exists to meet your needs. - </p><p> - In order to enable Multilib, you first need to ensure your recipe is - extended to support multiple libraries. - Many standard recipes are already extended and support multiple libraries. - You can check in the <code class="filename">meta/conf/multilib.conf</code> - configuration file in the source directory to see how this is - done using the <code class="filename">BBCLASSEXTEND</code> variable. - Eventually, all recipes will be covered and this list will be unneeded. - </p><p> - For the most part, the Multilib class extension works automatically to - extend the package name from <code class="filename">${PN}</code> to - <code class="filename">${MLPREFIX}${PN}</code>, where <code class="filename">MLPREFIX</code> - is the particular multilib (e.g. "lib32-" or "lib64-"). - Standard variables such as <code class="filename">DEPENDS</code>, - <code class="filename">RDEPENDS</code>, <code class="filename">RPROVIDES</code>, - <code class="filename">RRECOMMENDS</code>, <code class="filename">PACKAGES</code>, and - <code class="filename">PACKAGES_DYNAMIC</code> are automatically extended by the system. - If you are extending any manual code in the recipe, you can use the - <code class="filename">${MLPREFIX}</code> variable to ensure those names are extended - correctly. - This automatic extension code resides in <code class="filename">multilib.bbclass</code>. - </p></div><div class="section" title="4.5.2. Using Multilib"><div class="titlepage"><div><div><h3 class="title"><a id="using-multilib"></a>4.5.2. Using Multilib</h3></div></div></div><p> - After you have set up the recipes, you need to define the actual - combination of multiple libraries you want to build. - You accomplish this through your <code class="filename">local.conf</code> - configuration file in the - <a class="link" href="#build-directory">build directory</a>. - An example configuration would be as follows: - </p><pre class="literallayout"> - MACHINE = "qemux86-64" - require conf/multilib.conf - MULTILIBS = "multilib:lib32" - DEFAULTTUNE_virtclass-multilib-lib32 = "x86" - IMAGE_INSTALL = "lib32-connman" - </pre><p> - This example enables an - additional library named <code class="filename">lib32</code> alongside the - normal target packages. - When combining these "lib32" alternatives, the example uses "x86" for tuning. - For information on this particular tuning, see - <code class="filename">meta/conf/machine/include/ia32/arch-ia32.inc</code>. - </p><p> - The example then includes <code class="filename">lib32-connman</code> - in all the images, which illustrates one method of including a - multiple library dependency. - You can use a normal image build to include this dependency, - for example: - </p><pre class="literallayout"> - $ bitbake core-image-sato - </pre><p> - You can also build Multilib packages specifically with a command like this: - </p><pre class="literallayout"> - $ bitbake lib32-connman - </pre><p> - </p></div><div class="section" title="4.5.3. Additional Implementation Details"><div class="titlepage"><div><div><h3 class="title"><a id="additional-implementation-details"></a>4.5.3. Additional Implementation Details</h3></div></div></div><p> - Different packaging systems have different levels of native Multilib - support. - For the RPM Package Management System, the following implementation details - exist: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>A unique architecture is defined for the Multilib packages, - along with creating a unique deploy folder under - <code class="filename">tmp/deploy/rpm</code> in the - <a class="link" href="#build-directory">build directory</a>. - For example, consider <code class="filename">lib32</code> in a - <code class="filename">qemux86-64</code> image. - The possible architectures in the system are "all", "qemux86_64", - "lib32_qemux86_64", and "lib32_x86".</p></li><li class="listitem"><p>The <code class="filename">${MLPREFIX}</code> variable is stripped from - <code class="filename">${PN}</code> during RPM packaging. - The naming for a normal RPM package and a Multilib RPM package in a - <code class="filename">qemux86-64</code> system resolves to something similar to - <code class="filename">bash-4.1-r2.x86_64.rpm</code> and - <code class="filename">bash-4.1.r2.lib32_x86.rpm</code>, respectively. - </p></li><li class="listitem"><p>When installing a Multilib image, the RPM backend first - installs the base image and then installs the Multilib libraries. - </p></li><li class="listitem"><p>The build system relies on RPM to resolve the identical files in the - two (or more) Multilib packages.</p></li></ul></div><p> - </p><p> - For the IPK Package Management System, the following implementation details exist: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>The <code class="filename">${MLPREFIX}</code> is not stripped from - <code class="filename">${PN}</code> during IPK packaging. - The naming for a normal RPM package and a Multilib IPK package in a - <code class="filename">qemux86-64</code> system resolves to something like - <code class="filename">bash_4.1-r2.x86_64.ipk</code> and - <code class="filename">lib32-bash_4.1-rw_x86.ipk</code>, respectively. - </p></li><li class="listitem"><p>The IPK deploy folder is not modified with - <code class="filename">${MLPREFIX}</code> because packages with and without - the Multilib feature can exist in the same folder due to the - <code class="filename">${PN}</code> differences.</p></li><li class="listitem"><p>IPK defines a sanity check for Multilib installation - using certain rules for file comparison, overridden, etc. - </p></li></ul></div><p> - </p></div></div><div class="section" title="4.6. Configuring the Kernel"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="configuring-the-kernel"></a>4.6. Configuring the Kernel</h2></div></div></div><p> - Configuring the Yocto Project kernel consists of making sure the <code class="filename">.config</code> - file has all the right information in it for the image you are building. - You can use the <code class="filename">menuconfig</code> tool and configuration fragments to - make sure your <code class="filename">.config</code> file is just how you need it. - This section describes how to use <code class="filename">menuconfig</code>, create and use - configuration fragments, and how to interactively tweak your <code class="filename">.config</code> - file to create the leanest kernel configuration file possible. - </p><p> - For concepts on kernel configuration, see the - "<a class="link" href="#kernel-configuration" target="_top">Kernel Configuration</a>" - section in the Yocto Project Kernel Architecture and Use Manual. - </p><div class="section" title="4.6.1. Using menuconfig"><div class="titlepage"><div><div><h3 class="title"><a id="using-menuconfig"></a>4.6.1. Using <code class="filename">menuconfig</code></h3></div></div></div><p> - The easiest way to define kernel configurations is to set them through the - <code class="filename">menuconfig</code> tool. - For general information on <code class="filename">menuconfig</code>, see - <a class="ulink" href="http://en.wikipedia.org/wiki/Menuconfig" target="_top">http://en.wikipedia.org/wiki/Menuconfig</a>. - </p><p> - To use the <code class="filename">menuconfig</code> tool in the Yocto Project development - environment, you must build the tool using BitBake. - The following commands build and invoke <code class="filename">menuconfig</code> assuming the - source directory top-level folder is <code class="filename">~/poky</code>: - </p><pre class="literallayout"> - $ cd ~/poky - $ source oe-init-build-env - $ bitbake linux-yocto -c menuconfig - </pre><p> - Once <code class="filename">menuconfig</code> comes up, its standard interface allows you to - examine and configure all the kernel configuration parameters. - Once you have made your changes, simply exit the tool and save your changes to - create an updated version of the <code class="filename">.config</code> configuration file. - </p><p> - For an example that shows how to change a specific kernel option - using <code class="filename">menuconfig</code>, see the - "<a class="link" href="#changing-the-config-smp-configuration-using-menuconfig" title="B.2.3. Changing the CONFIG_SMP Configuration Using menuconfig">Changing - the <code class="filename">CONFIG_SMP</code> Configuration Using <code class="filename">menuconfig</code></a>" - section. - </p></div><div class="section" title="4.6.2. Creating Configuration Fragments"><div class="titlepage"><div><div><h3 class="title"><a id="creating-config-fragments"></a>4.6.2. Creating Configuration Fragments</h3></div></div></div><p> - Configuration fragments are simply kernel options that appear in a file - placed where the OpenEmbedded build system can find and apply them. - Syntactically, the configuration statement is identical to what would appear - in the <code class="filename">.config</code> file, which is in the - <a class="link" href="#build-directory">build directory</a> in - <code class="filename">tmp/work/<arch>-poky-linux/linux-yocto-<release-specific-string>/linux-<arch>-<build-type></code>. - </p><p> - It is simple to create a configuration fragment. - For example, issuing the following from the shell creates a configuration fragment - file named <code class="filename">my_smp.cfg</code> that enables multi-processor support - within the kernel: - </p><pre class="literallayout"> - $ echo "CONFIG_SMP=y" >> my_smp.cfg - </pre><p> - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3> - All configuration files must use the <code class="filename">.cfg</code> extension in order - for the OpenEmbedded build system to recognize them as a configuration fragment. - </div><p> - </p><p> - Where do you put your configuration files? - You can place these configuration files in the same area pointed to by - <code class="filename">SRC_URI</code>. - The OpenEmbedded build system will pick up the configuration and add it to the - kernel's configuration. - For example, suppose you had a set of configuration options in a file called - <code class="filename">myconfig.cfg</code>. - If you put that file inside a directory named <code class="filename">/linux-yocto</code> - that resides in the same directory as the kernel's append file and then add - a <code class="filename">SRC_URI</code> statement such as the following to the kernel's append file, - those configuration options will be picked up and applied when the kernel is built. - </p><pre class="literallayout"> - SRC_URI += "file://myconfig.cfg" - </pre><p> - </p><p> - As mentioned earlier, you can group related configurations into multiple files and - name them all in the <code class="filename">SRC_URI</code> statement as well. - For example, you could group separate configurations specifically for Ethernet and graphics - into their own files and add those by using a <code class="filename">SRC_URI</code> statement like the - following in your append file: - </p><pre class="literallayout"> - SRC_URI += "file://myconfig.cfg \ - file://eth.cfg \ - file://gfx.cfg" - </pre><p> - </p></div><div class="section" title="4.6.3. Fine-tuning the Kernel Configuration File"><div class="titlepage"><div><div><h3 class="title"><a id="fine-tuning-the-kernel-configuration-file"></a>4.6.3. Fine-tuning the Kernel Configuration File</h3></div></div></div><p> - You can make sure the <code class="filename">.config</code> is as lean or efficient as - possible by reading the output of the kernel configuration fragment audit, - noting any issues, making changes to correct the issues, and then repeating. - </p><p> - As part of the kernel build process, the - <code class="filename">kernel_configcheck</code> task runs. - This task validates the kernel configuration by checking the final - <code class="filename">.config</code> file against the input files. - During the check, the task produces warning messages for the following - issues: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>Requested options that did not make the final - <code class="filename">.config</code> file.</p></li><li class="listitem"><p>Configuration items that appear twice in the same - configuration fragment.</p></li><li class="listitem"><p>Configuration items tagged as 'required' were overridden. - </p></li><li class="listitem"><p>A board overrides a non-board specific option.</p></li><li class="listitem"><p>Listed options not valid for the kernel being processed. - In other words, the option does not appear anywhere.</p></li></ul></div><p> - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3> - The <code class="filename">kernel_configcheck</code> task can also optionally report - if an option is overridden during processing. - </div><p> - </p><p> - For each output warning, a message points to the file - that contains a list of the options and a pointer to the config - fragment that defines them. - Collectively, the files are the key to streamlining the configuration. - </p><p> - To streamline the configuration, do the following: - </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Start with a full configuration that you know - works - it builds and boots successfully. - This configuration file will be your baseline.</p></li><li class="listitem"><p>Separately run the <code class="filename">configme</code> and - <code class="filename">kernel_configcheck</code> tasks.</p></li><li class="listitem"><p>Take the resulting list of files from the - <code class="filename">kernel_configcheck</code> task warnings and do the following: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>Drop values that are redefined in the fragment but do not - change the final <code class="filename">.config</code> file.</p></li><li class="listitem"><p>Analyze and potentially drop values from the - <code class="filename">.config</code> file that override required - configurations.</p></li><li class="listitem"><p>Analyze and potentially remove non-board specific options. - </p></li><li class="listitem"><p>Remove repeated and invalid options.</p></li></ul></div></li><li class="listitem"><p>After you have worked through the output of the kernel configuration - audit, you can re-run the <code class="filename">configme</code> - and <code class="filename">kernel_configcheck</code> tasks to see the results of your - changes. - If you have more issues, you can deal with them as described in the - previous step.</p></li></ol></div><p> - </p><p> - Iteratively working through steps two through four eventually yields - a minimal, streamlined configuration file. - Once you have the best <code class="filename">.config</code>, you can build the Linux - Yocto kernel. - </p></div></div><div class="section" title="4.7. Updating Existing Images"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="usingpoky-changes-updatingimages"></a>4.7. Updating Existing Images</h2></div></div></div><p> - Often, rather than re-flashing a new image, you might wish to install updated - packages into an existing running system. - You can do this by first sharing the <code class="filename">tmp/deploy/ipk/</code> directory - through a web server and then by changing <code class="filename">/etc/opkg/base-feeds.conf</code> - to point at the shared server. - Following is an example: - </p><pre class="literallayout"> - $ src/gz all http://www.mysite.com/somedir/deploy/ipk/all - $ src/gz armv7a http://www.mysite.com/somedir/deploy/ipk/armv7a - $ src/gz beagleboard http://www.mysite.com/somedir/deploy/ipk/beagleboard - </pre><p> - </p></div><div class="section" title="4.8. Incrementing a Package Revision Number"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="usingpoky-changes-prbump"></a>4.8. Incrementing a Package Revision Number</h2></div></div></div><p> - If a committed change results in changing the package output, - then the value of the - <code class="filename"><a class="link" href="#var-PR" target="_top">PR</a></code> - variable needs to be increased - (or "bumped") as part of that commit. - This means that for new recipes you must be sure to add the <code class="filename">PR</code> - variable and set its initial value equal to "r0". - Failing to define <code class="filename">PR</code> makes it easy to miss when you bump a package. - Note that you can only use integer values following the "r" in the - <code class="filename">PR</code> variable. - </p><p> - If you are sharing a common <code class="filename">.inc</code> file with multiple recipes, - you can also use the - <code class="filename"><a class="link" href="#var-INC_PR" target="_top">INC_PR</a></code> - variable to ensure that - the recipes sharing the <code class="filename">.inc</code> file are rebuilt when the - <code class="filename">.inc</code> file itself is changed. - The <code class="filename">.inc</code> file must set <code class="filename">INC_PR</code> - (initially to "r0"), and all recipes referring to it should set <code class="filename">PR</code> - to "$(INC_PR).0" initially, incrementing the last number when the recipe is changed. - If the <code class="filename">.inc</code> file is changed then its - <code class="filename">INC_PR</code> should be incremented. - </p><p> - When upgrading the version of a package, assuming the - <code class="filename"><a class="link" href="#var-PV" target="_top">PV</a></code> - changes, the <code class="filename">PR</code> variable should be reset to "r0" - (or "$(INC_PR).0" if you are using <code class="filename">INC_PR</code>). - </p><p> - Usually, version increases occur only to packages. - However, if for some reason <code class="filename">PV</code> changes but does not - increase, you can increase the - <code class="filename"><a class="link" href="#var-PE" target="_top">PE</a></code> - variable (Package Epoch). - The <code class="filename">PE</code> variable defaults to "0". - </p><p> - Version numbering strives to follow the - <a class="ulink" href="http://www.debian.org/doc/debian-policy/ch-controlfields.html" target="_top"> - Debian Version Field Policy Guidelines</a>. - These guidelines define how versions are compared and what "increasing" a version means. - </p><p> - There are two reasons for following the previously mentioned guidelines. - First, to ensure that when a developer updates and rebuilds, they get all the changes to - the repository and do not have to remember to rebuild any sections. - Second, to ensure that target users are able to upgrade their - devices using package manager commands such as <code class="filename">opkg upgrade</code> - (or similar commands for dpkg/apt or rpm-based systems). - </p><p> - The goal is to ensure the Yocto Project has packages that can be upgraded in all cases. - </p></div><div class="section" title="4.9. Handling a Package Name Alias"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="usingpoky-configuring-DISTRO_PN_ALIAS"></a>4.9. Handling a Package Name Alias</h2></div></div></div><p> - Sometimes a package name you are using might exist under an alias or as a similarly named - package in a different distribution. - The OpenEmbedded build system implements a <code class="filename">distro_check</code> - task that automatically connects to major distributions - and checks for these situations. - If the package exists under a different name in a different distribution, you get a - <code class="filename">distro_check</code> mismatch. - You can resolve this problem by defining a per-distro recipe name alias using the - <code class="filename"><a class="link" href="#var-DISTRO_PN_ALIAS" target="_top">DISTRO_PN_ALIAS</a></code> - variable. - </p><p> - Following is an example that shows how you specify the <code class="filename">DISTRO_PN_ALIAS</code> - variable: - </p><pre class="literallayout"> - DISTRO_PN_ALIAS_pn-PACKAGENAME = "distro1=package_name_alias1 \ - distro2=package_name_alias2 \ - distro3=package_name_alias3 \ - ..." - </pre><p> - </p><p> - If you have more than one distribution alias, separate them with a space. - Note that the build system currently automatically checks the - Fedora, OpenSuSE, Debian, Ubuntu, - and Mandriva distributions for source package recipes without having to specify them - using the <code class="filename">DISTRO_PN_ALIAS</code> variable. - For example, the following command generates a report that lists the Linux distributions - that include the sources for each of the recipes. - </p><pre class="literallayout"> - $ bitbake world -f -c distro_check - </pre><p> - The results are stored in the <code class="filename">build/tmp/log/distro_check-${DATETIME}.results</code> - file found in the source directory. - </p></div><div class="section" title="4.10. Building Software from an External Source"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="building-software-from-an-external-source"></a>4.10. Building Software from an External Source</h2></div></div></div><p> - By default, the OpenEmbedded build system does its work from within the - <a class="link" href="#build-directory">build directory</a>. - The build process involves fetching the source files, unpacking them, and then patching them - if necessary before the build takes place. - </p><p> - Situations exist where you might want to build software from source files that are external to - and thus outside of the <a class="link" href="#source-directory">source directory</a>. - For example, suppose you have a project that includes a new BSP with a heavily customized - kernel, a very minimal image, and some new user-space recipes. - And, you want to minimize the exposure to the build system to the - development team so that they can focus on their project and maintain everyone's workflow - as much as possible. - In this case, you want a kernel source directory on the development machine where the - development occurs. - You want the recipe's - <a class="link" href="#var-SRC_URI" target="_top"><code class="filename">SRC_URI</code></a> - variable to point to the external directory and use it as is, not copy it. - </p><p> - To build from software that comes from an external source, all you need to do is - change your recipe so that it inherits the - <a class="link" href="#ref-classes-externalsrc" target="_top"><code class="filename">externalsrc.bbclass</code></a> - class and then sets the - <a class="link" href="#var-S" target="_top"><code class="filename">S</code></a> - variable to point to your external source code. - Here are the statements to put in your recipe: - </p><pre class="literallayout"> - inherit externalsrc - S = "/some/path/to/your/package/source" - </pre><p> - </p><p> - It is important to know that the <code class="filename">externalsrc.bbclass</code> assumes that the - source directory <code class="filename">S</code> and the build directory - <a class="link" href="#var-B" target="_top"><code class="filename">B</code></a> - are different even though by default these directories are the same. - This assumption is important because it supports building different variants of the recipe - by using the - <a class="link" href="#var-BBCLASSEXTEND" target="_top"><code class="filename">BBCLASSEXTEND</code></a> - variable. - You could allow the build directory to be the same as the source directory but you would - not be able to build more than one variant of the recipe. - Consequently, if you are building multiple variants of the recipe, you need to establish a - build directory that is different than the source directory. - </p></div><div class="section" title="4.11. Excluding Recipes From the Build"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="excluding-recipes-from-the-build"></a>4.11. Excluding Recipes From the Build</h2></div></div></div><p> - You might find that there are groups of recipes you want to filter - out of the build process. - For example, recipes you know you will never use or want should not - be part of the build. - Removing these recipes from parsing speeds up parts of the build. - </p><p> - It is possible to filter or mask out <code class="filename">.bb</code> and - <code class="filename">.bbappend</code> files. - You can do this by providing an expression with the - <code class="filename"><a class="link" href="#var-BBMASK" target="_top">BBMASK</a></code> - variable. - Here is an example: - </p><pre class="literallayout"> - BBMASK = ".*/meta-mymachine/recipes-maybe/" - </pre><p> - Here, all <code class="filename">.bb</code> and <code class="filename">.bbappend</code> files - in the directory that match the expression are ignored during the build - process. - </p></div><div class="section" title="4.12. Using an External SCM"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="platdev-appdev-srcrev"></a>4.12. Using an External SCM</h2></div></div></div><p> - If you're working on a recipe that pulls from an external Source Code Manager (SCM), it - is possible to have the OpenEmbedded build system notice new changes added to the - SCM and then build the package that depends on them using the latest version. - This only works for SCMs from which it is possible to get a sensible revision number for changes. - Currently, you can do this with Apache Subversion (SVN), Git, and Bazaar (BZR) repositories. - </p><p> - To enable this behavior, simply add the following to the <code class="filename">local.conf</code> - configuration file found in the - <a class="link" href="#build-directory" target="_top">build directory</a>: - </p><pre class="literallayout"> - SRCREV_pn-<PN> = "${AUTOREV}" - </pre><p> - where <code class="filename">PN</code> - is the name of the package for which you want to enable automatic source - revision updating. - </p></div><div class="section" title="4.13. Debugging With the GNU Project Debugger (GDB) Remotely"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="platdev-gdb-remotedebug"></a>4.13. Debugging With the GNU Project Debugger (GDB) Remotely</h2></div></div></div><p> - GDB allows you to examine running programs, which in turn help you to understand and fix problems. - It also allows you to perform post-mortem style analysis of program crashes. - GDB is available as a package within the Yocto Project and by default is - installed in sdk images. - See the "<a class="link" href="#ref-images" target="_top">Images</a>" chapter - in the Yocto Project Reference Manual for a description of these images. - You can find information on GDB at <a class="ulink" href="http://sourceware.org/gdb/" target="_top">http://sourceware.org/gdb/</a>. - </p><div class="tip" title="Tip" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Tip</h3> - For best results, install <code class="filename">-dbg</code> packages for the applications - you are going to debug. - Doing so makes available extra debug symbols that give you more meaningful output. - </div><p> - Sometimes, due to memory or disk space constraints, it is not possible - to use GDB directly on the remote target to debug applications. - These constraints arise because GDB needs to load the debugging information and the - binaries of the process being debugged. - Additionally, GDB needs to perform many computations to locate information such as function - names, variable names and values, stack traces and so forth - even before starting the - debugging process. - These extra computations place more load on the target system and can alter the - characteristics of the program being debugged. - </p><p> - To help get past the previously mentioned constraints, you can use Gdbserver. - Gdbserver runs on the remote target and does not load any debugging information - from the debugged process. - Instead, a GDB instance processes the debugging information that is run on a - remote computer - the host GDB. - The host GDB then sends control commands to Gdbserver to make it stop or start the debugged - program, as well as read or write memory regions of that debugged program. - All the debugging information loaded and processed as well - as all the heavy debugging is done by the host GDB. - Offloading these processes gives the Gdbserver running on the target a chance to remain - small and fast. - </p><p> - Because the host GDB is responsible for loading the debugging information and - for doing the necessary processing to make actual debugging happen, the - user has to make sure the host can access the unstripped binaries complete - with their debugging information and also be sure the target is compiled with no optimizations. - The host GDB must also have local access to all the libraries used by the - debugged program. - Because Gdbserver does not need any local debugging information, the binaries on - the remote target can remain stripped. - However, the binaries must also be compiled without optimization - so they match the host's binaries. - </p><p> - To remain consistent with GDB documentation and terminology, the binary being debugged - on the remote target machine is referred to as the "inferior" binary. - For documentation on GDB see the - <a class="ulink" href="http://sourceware.org/gdb/documentation/" target="_top">GDB site</a>. - </p><div class="section" title="4.13.1. Launching Gdbserver on the Target"><div class="titlepage"><div><div><h3 class="title"><a id="platdev-gdb-remotedebug-launch-gdbserver"></a>4.13.1. Launching Gdbserver on the Target</h3></div></div></div><p> - First, make sure Gdbserver is installed on the target. - If it is not, install the package <code class="filename">gdbserver</code>, which needs the - <code class="filename">libthread-db1</code> package. - </p><p> - As an example, to launch Gdbserver on the target and make it ready to "debug" a - program located at <code class="filename">/path/to/inferior</code>, connect - to the target and launch: - </p><pre class="literallayout"> - $ gdbserver localhost:2345 /path/to/inferior - </pre><p> - Gdbserver should now be listening on port 2345 for debugging - commands coming from a remote GDB process that is running on the host computer. - Communication between Gdbserver and the host GDB are done using TCP. - To use other communication protocols, please refer to the - <a class="ulink" href="http://www.gnu.org/software/gdb/" target="_top">Gdbserver documentation</a>. - </p></div><div class="section" title="4.13.2. Launching GDB on the Host Computer"><div class="titlepage"><div><div><h3 class="title"><a id="platdev-gdb-remotedebug-launch-gdb"></a>4.13.2. Launching GDB on the Host Computer</h3></div></div></div><p> - Running GDB on the host computer takes a number of stages. - This section describes those stages. - </p><div class="section" title="4.13.2.1. Building the Cross-GDB Package"><div class="titlepage"><div><div><h4 class="title"><a id="platdev-gdb-remotedebug-launch-gdb-buildcross"></a>4.13.2.1. Building the Cross-GDB Package</h4></div></div></div><p> - A suitable GDB cross-binary is required that runs on your host computer but - also knows about the the ABI of the remote target. - You can get this binary from the meta-toolchain. - Here is an example: - </p><pre class="literallayout"> - /usr/local/poky/eabi-glibc/arm/bin/arm-poky-linux-gnueabi-gdb - </pre><p> - where <code class="filename">arm</code> is the target architecture and - <code class="filename">linux-gnueabi</code> the target ABI. - </p><p> - Alternatively, you can use BitBake to build the <code class="filename">gdb-cross</code> binary. - Here is an example: - </p><pre class="literallayout"> - $ bitbake gdb-cross - </pre><p> - Once the binary is built, you can find it here: - </p><pre class="literallayout"> - tmp/sysroots/<host-arch>/usr/bin/<target-abi>-gdb - </pre><p> - </p></div><div class="section" title="4.13.2.2. Making the Inferior Binaries Available"><div class="titlepage"><div><div><h4 class="title"><a id="platdev-gdb-remotedebug-launch-gdb-inferiorbins"></a>4.13.2.2. Making the Inferior Binaries Available</h4></div></div></div><p> - The inferior binary (complete with all debugging symbols) as well as any - libraries (and their debugging symbols) on which the inferior binary depends - need to be available. - There are a number of ways you can make these available. - </p><p> - Perhaps the easiest way is to have an 'sdk' image that corresponds to the plain - image installed on the device. - In the case of <code class="filename">core-image-sato</code>, - <code class="filename">core-image-sato-sdk</code> would contain suitable symbols. - Because the sdk images already have the debugging symbols installed, it is just a - question of expanding the archive to some location and then informing GDB. - </p><p> - Alternatively, the OpenEmbedded build system can build a custom directory of files - for a specific - debugging purpose by reusing its <code class="filename">tmp/rootfs</code> directory. - This directory contains the contents of the last built image. - This process assumes two things: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>The image running on the target was the last image to - be built.</p></li><li class="listitem"><p>The package (<code class="filename">foo</code> in the following - example) that contains the inferior binary to be debugged has been built - without optimization and has debugging information available.</p></li></ul></div><p> - </p><p> - The following steps show how to build the custom directory of files: - </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Install the package (<code class="filename">foo</code> in this case) to - <code class="filename">tmp/rootfs</code>: - </p><pre class="literallayout"> - $ tmp/sysroots/i686-linux/usr/bin/opkg-cl -f \ - tmp/work/<target-abi>/core-image-sato-1.0-r0/temp/opkg.conf -o \ - tmp/rootfs/ update - </pre></li><li class="listitem"><p>Install the debugging information: - </p><pre class="literallayout"> - $ tmp/sysroots/i686-linux/usr/bin/opkg-cl -f \ - tmp/work/<target-abi>/core-image-sato-1.0-r0/temp/opkg.conf \ - -o tmp/rootfs install foo - - $ tmp/sysroots/i686-linux/usr/bin/opkg-cl -f \ - tmp/work/<target-abi>/core-image-sato-1.0-r0/temp/opkg.conf \ - -o tmp/rootfs install foo-dbg - </pre></li></ol></div><p> - </p></div><div class="section" title="4.13.2.3. Launch the Host GDB"><div class="titlepage"><div><div><h4 class="title"><a id="platdev-gdb-remotedebug-launch-gdb-launchhost"></a>4.13.2.3. Launch the Host GDB</h4></div></div></div><p> - To launch the host GDB, you run the <code class="filename">cross-gdb</code> binary and provide - the inferior binary as part of the command line. - For example, the following command form continues with the example used in - the previous section. - This command form loads the <code class="filename">foo</code> binary - as well as the debugging information: - </p><pre class="literallayout"> - $ <target-abi>-gdb rootfs/usr/bin/foo - </pre><p> - Once the GDB prompt appears, you must instruct GDB to load all the libraries - of the inferior binary from <code class="filename">tmp/rootfs</code> as follows: - </p><pre class="literallayout"> - $ set solib-absolute-prefix /path/to/tmp/rootfs - </pre><p> - The pathname <code class="filename">/path/to/tmp/rootfs</code> must either be - the absolute path to <code class="filename">tmp/rootfs</code> or the location at which - binaries with debugging information reside. - </p><p> - At this point you can have GDB connect to the Gdbserver that is running - on the remote target by using the following command form: - </p><pre class="literallayout"> - $ target remote remote-target-ip-address:2345 - </pre><p> - The <code class="filename">remote-target-ip-address</code> is the IP address of the - remote target where the Gdbserver is running. - Port 2345 is the port on which the GDBSERVER is running. - </p></div><div class="section" title="4.13.2.4. Using the Debugger"><div class="titlepage"><div><div><h4 class="title"><a id="platdev-gdb-remotedebug-launch-gdb-using"></a>4.13.2.4. Using the Debugger</h4></div></div></div><p> - You can now proceed with debugging as normal - as if you were debugging - on the local machine. - For example, to instruct GDB to break in the "main" function and then - continue with execution of the inferior binary use the following commands - from within GDB: - </p><pre class="literallayout"> - (gdb) break main - (gdb) continue - </pre><p> - </p><p> - For more information about using GDB, see the project's online documentation at - <a class="ulink" href="http://sourceware.org/gdb/download/onlinedocs/" target="_top">http://sourceware.org/gdb/download/onlinedocs/</a>. - </p></div></div></div><div class="section" title="4.14. Profiling with OProfile"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="platdev-oprofile"></a>4.14. Profiling with OProfile</h2></div></div></div><p> - <a class="ulink" href="http://oprofile.sourceforge.net/" target="_top">OProfile</a> is a - statistical profiler well suited for finding performance - bottlenecks in both userspace software and in the kernel. - This profiler provides answers to questions like "Which functions does my application spend - the most time in when doing X?" - Because the OpenEmbedded build system is well integrated with OProfile, it makes profiling - applications on target hardware straightforward. - </p><p> - To use OProfile, you need an image that has OProfile installed. - The easiest way to do this is with <code class="filename">tools-profile</code> in the - <code class="filename"><a class="link" href="#var-IMAGE_FEATURES" target="_top">IMAGE_FEATURES</a></code> variable. - You also need debugging symbols to be available on the system where the analysis - takes place. - You can gain access to the symbols by using <code class="filename">dbg-pkgs</code> in the - <code class="filename">IMAGE_FEATURES</code> variable or by - installing the appropriate <code class="filename">-dbg</code> packages. - </p><p> - For successful call graph analysis, the binaries must preserve the frame - pointer register and should also be compiled with the - <code class="filename">-fno-omit-framepointer</code> flag. - You can achieve this by setting the - <code class="filename"><a class="link" href="#var-SELECTED_OPTIMIZATION" target="_top">SELECTED_OPTIMIZATION</a></code> - variable to - <code class="filename">-fexpensive-optimizations -fno-omit-framepointer -frename-registers -O2</code>. - You can also achieve it by setting the - <code class="filename"><a class="link" href="#var-DEBUG_BUILD" target="_top">DEBUG_BUILD</a></code> - variable to "1" in the <code class="filename">local.conf</code> configuration file. - If you use the <code class="filename">DEBUG_BUILD</code> variable you will also add extra debug information - that can make the debug packages large. - </p><div class="section" title="4.14.1. Profiling on the Target"><div class="titlepage"><div><div><h3 class="title"><a id="platdev-oprofile-target"></a>4.14.1. Profiling on the Target</h3></div></div></div><p> - Using OProfile you can perform all the profiling work on the target device. - A simple OProfile session might look like the following: - </p><p> - </p><pre class="literallayout"> - # opcontrol --reset - # opcontrol --start --separate=lib --no-vmlinux -c 5 - . - . - [do whatever is being profiled] - . - . - # opcontrol --stop - $ opreport -cl - </pre><p> - </p><p> - In this example, the <code class="filename">reset</code> command clears any previously profiled data. - The next command starts OProfile. - The options used when starting the profiler separate dynamic library data - within applications, disable kernel profiling, and enable callgraphing up to - five levels deep. - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3> - To profile the kernel, you would specify the - <code class="filename">--vmlinux=/path/to/vmlinux</code> option. - The <code class="filename">vmlinux</code> file is usually in the source directory in the - <code class="filename">/boot/</code> directory and must match the running kernel. - </div><p> - </p><p> - After you perform your profiling tasks, the next command stops the profiler. - After that, you can view results with the <code class="filename">opreport</code> command with options - to see the separate library symbols and callgraph information. - </p><p> - Callgraphing logs information about time spent in functions and about a function's - calling function (parent) and called functions (children). - The higher the callgraphing depth, the more accurate the results. - However, higher depths also increase the logging overhead. - Consequently, you should take care when setting the callgraphing depth. - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3> - On ARM, binaries need to have the frame pointer enabled for callgraphing to work. - To accomplish this use the <code class="filename">-fno-omit-framepointer</code> option - with <code class="filename">gcc</code>. - </div><p> - </p><p> - For more information on using OProfile, see the OProfile - online documentation at - <a class="ulink" href="http://oprofile.sourceforge.net/docs/" target="_top">http://oprofile.sourceforge.net/docs/</a>. - </p></div><div class="section" title="4.14.2. Using OProfileUI"><div class="titlepage"><div><div><h3 class="title"><a id="platdev-oprofile-oprofileui"></a>4.14.2. Using OProfileUI</h3></div></div></div><p> - A graphical user interface for OProfile is also available. - You can download and build this interface from the Yocto Project at - <a class="ulink" href="http://git.yoctoproject.org/cgit.cgi/oprofileui/" target="_top">http://git.yoctoproject.org/cgit.cgi/oprofileui/</a>. - If the "tools-profile" image feature is selected, all necessary binaries - are installed onto the target device for OProfileUI interaction. - </p><p> - Even though the source directory usually includes all needed patches on the target device, you - might find you need other OProfile patches for recent OProfileUI features. - If so, see the <a class="ulink" href="http://git.yoctoproject.org/cgit.cgi/oprofileui/tree/README" target="_top"> - OProfileUI README</a> for the most recent information. - </p><div class="section" title="4.14.2.1. Online Mode"><div class="titlepage"><div><div><h4 class="title"><a id="platdev-oprofile-oprofileui-online"></a>4.14.2.1. Online Mode</h4></div></div></div><p> - Using OProfile in online mode assumes a working network connection with the target - hardware. - With this connection, you just need to run "oprofile-server" on the device. - By default, OProfile listens on port 4224. - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3> - You can change the port using the <code class="filename">--port</code> command-line - option. - </div><p> - </p><p> - The client program is called <code class="filename">oprofile-viewer</code> and its UI is relatively - straightforward. - You access key functionality through the buttons on the toolbar, which - are duplicated in the menus. - Here are the buttons: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><span class="emphasis"><em>Connect:</em></span> Connects to the remote host. - You can also supply the IP address or hostname.</p></li><li class="listitem"><p><span class="emphasis"><em>Disconnect:</em></span> Disconnects from the target. - </p></li><li class="listitem"><p><span class="emphasis"><em>Start:</em></span> Starts profiling on the device. - </p></li><li class="listitem"><p><span class="emphasis"><em>Stop:</em></span> Stops profiling on the device and - downloads the data to the local host. - Stopping the profiler generates the profile and displays it in the viewer. - </p></li><li class="listitem"><p><span class="emphasis"><em>Download:</em></span> Downloads the data from the - target and generates the profile, which appears in the viewer.</p></li><li class="listitem"><p><span class="emphasis"><em>Reset:</em></span> Resets the sample data on the device. - Resetting the data removes sample information collected from previous - sampling runs. - Be sure you reset the data if you do not want to include old sample information. - </p></li><li class="listitem"><p><span class="emphasis"><em>Save:</em></span> Saves the data downloaded from the - target to another directory for later examination.</p></li><li class="listitem"><p><span class="emphasis"><em>Open:</em></span> Loads previously saved data. - </p></li></ul></div><p> - </p><p> - The client downloads the complete 'profile archive' from - the target to the host for processing. - This archive is a directory that contains the sample data, the object files, - and the debug information for the object files. - The archive is then converted using the <code class="filename">oparchconv</code> script, which is - included in this distribution. - The script uses <code class="filename">opimport</code> to convert the archive from - the target to something that can be processed on the host. - </p><p> - Downloaded archives reside in the build directory in - <code class="filename">/tmp</code> and are cleared up when they are no longer in use. - </p><p> - If you wish to perform kernel profiling, you need to be sure - a <code class="filename">vmlinux</code> file that matches the running kernel is available. - In the source directory, that file is usually located in - <code class="filename">/boot/vmlinux-KERNELVERSION</code>, where - <code class="filename">KERNEL-version</code> is the version of the kernel. - The OpenEmbedded build system generates separate <code class="filename">vmlinux</code> - packages for each kernel it builds. - Thus, it should just be a question of making sure a matching package is - installed (e.g. <code class="filename">opkg install kernel-vmlinux</code>. - The files are automatically installed into development and profiling images - alongside OProfile. - A configuration option exists within the OProfileUI settings page that you can use to - enter the location of the <code class="filename">vmlinux</code> file. - </p><p> - Waiting for debug symbols to transfer from the device can be slow, and it - is not always necessary to actually have them on the device for OProfile use. - All that is needed is a copy of the filesystem with the debug symbols present - on the viewer system. - The "<a class="link" href="#platdev-gdb-remotedebug-launch-gdb" title="4.13.2. Launching GDB on the Host Computer">Launching GDB on the Host Computer</a>" - section covers how to create such a directory with - the source directory and how to use the OProfileUI Settings dialog to specify the location. - If you specify the directory, it will be used when the file checksums - match those on the system you are profiling. - </p></div><div class="section" title="4.14.2.2. Offline Mode"><div class="titlepage"><div><div><h4 class="title"><a id="platdev-oprofile-oprofileui-offline"></a>4.14.2.2. Offline Mode</h4></div></div></div><p> - If network access to the target is unavailable, you can generate - an archive for processing in <code class="filename">oprofile-viewer</code> as follows: - </p><pre class="literallayout"> - # opcontrol --reset - # opcontrol --start --separate=lib --no-vmlinux -c 5 - . - . - [do whatever is being profiled] - . - . - # opcontrol --stop - # oparchive -o my_archive - </pre><p> - </p><p> - In the above example, <code class="filename">my_archive</code> is the name of the - archive directory where you would like the profile archive to be kept. - After the directory is created, you can copy it to another host and load it - using <code class="filename">oprofile-viewer</code> open functionality. - If necessary, the archive is converted. - </p></div></div></div></div> - - <div class="chapter" title="Chapter 5. Common Development Models"><div class="titlepage"><div><div><h2 class="title"><a id="dev-manual-model"></a>Chapter 5. Common Development Models</h2></div></div></div><div class="toc"><dl><dt><span class="section"><a href="#system-development-model">5.1. System Development Workflow</a></span></dt><dd><dl><dt><span class="section"><a href="#developing-a-board-support-package-bsp">5.1.1. Developing a Board Support Package (BSP)</a></span></dt><dt><span class="section"><a href="#modifying-the-kernel">5.1.2. Modifying the Kernel</a></span></dt></dl></dd><dt><span class="section"><a href="#application-development-workflow">5.2. Application Development Workflow</a></span></dt><dd><dl><dt><span class="section"><a href="#workflow-using-the-adt-and-eclipse">5.2.1. Workflow Using the ADT and <span class="trademark">Eclipse</span>™</a></span></dt><dt><span class="section"><a href="#adt-eclipse">5.2.2. Working Within Eclipse</a></span></dt><dt><span class="section"><a href="#workflow-using-stand-alone-cross-development-toolchains">5.2.3. Workflow Using Stand-alone Cross-development Toolchains</a></span></dt></dl></dd><dt><span class="section"><a href="#modifying-temporary-source-code">5.3. Modifying Temporary Source Code</a></span></dt><dd><dl><dt><span class="section"><a href="#finding-the-temporary-source-code">5.3.1. Finding the Temporary Source Code</a></span></dt><dt><span class="section"><a href="#using-a-quilt-workflow">5.3.2. Using a Quilt Workflow</a></span></dt><dt><span class="section"><a href="#using-a-git-workflow">5.3.3. Using a Git Workflow</a></span></dt></dl></dd><dt><span class="section"><a href="#image-development-using-hob">5.4. Image Development Using Hob</a></span></dt><dt><span class="section"><a href="#platdev-appdev-devshell">5.5. Using a Development Shell</a></span></dt></dl></div><p> - Many development models exist for which you can use the Yocto Project. - This chapter overviews the following methods: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><span class="emphasis"><em>System Development:</em></span> - System Development covers Board Support Package (BSP) development and kernel - modification or configuration. - If you want to examine specific examples of the system development models, - see the "<a class="link" href="#dev-manual-bsp-appendix" title="Appendix A. BSP Development Example">BSP Development Example</a>" - appendix and the - "<a class="link" href="#dev-manual-kernel-appendix" title="Appendix B. Kernel Modification Example">Kernel Modification Example</a>" appendix. - </p></li><li class="listitem"><p><span class="emphasis"><em>User Application Development:</em></span> - User Application Development covers development of applications that you intend - to run on some target hardware. - For a user-space application development example that uses the - <span class="trademark">Eclipse</span>™ IDE, - see the - Yocto Project Application Developer's Guide. - </p></li><li class="listitem"><p><span class="emphasis"><em>Temporary Source Code Modification:</em></span> - Direct modification of temporary source code is a convenient development model - to quickly iterate and develop towards a solution. - Once the solution has been implemented, you should of course take steps to - get the changes upstream and applied in the affected recipes.</p></li><li class="listitem"><p><span class="emphasis"><em>Image Development using Hob:</em></span> - You can use the <a class="ulink" href="http://www.yoctoproject.org/projects/hob" target="_top">Hob</a> to build - custom operating system images within the build environment. - Hob provides an efficient interface to the OpenEmbedded build system.</p></li><li class="listitem"><p><span class="emphasis"><em>Using a Development Shell:</em></span> - You can use a <code class="filename">devshell</code> to efficiently debug commands or simply - edit packages. - Working inside a development shell is a quick way to set up the OpenEmbedded build - environment to work on parts of a project.</p></li></ul></div><p> -</p><div class="section" title="5.1. System Development Workflow"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="system-development-model"></a>5.1. System Development Workflow</h2></div></div></div><p> - System development involves modification or creation of an image that you want to run on - a specific hardware target. - Usually, when you want to create an image that runs on embedded hardware, the image does - not require the same number of features that a full-fledged Linux distribution provides. - Thus, you can create a much smaller image that is designed to use only the hardware - features for your particular hardware. - </p><p> - To help you understand how system development works in the Yocto Project, this section - covers two types of image development: BSP creation and kernel modification or - configuration. - </p><div class="section" title="5.1.1. Developing a Board Support Package (BSP)"><div class="titlepage"><div><div><h3 class="title"><a id="developing-a-board-support-package-bsp"></a>5.1.1. Developing a Board Support Package (BSP)</h3></div></div></div><p> - A BSP is a packageof recipes that, when applied, during a build results in - an image that you can run on a particular board. - Thus, the package, when compiled into the new image, supports the operation of the board. - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3> - For a brief list of terms used when describing the development process in the Yocto Project, - see the "<a class="link" href="#yocto-project-terms" title="3.4. Yocto Project Terms">Yocto Project Terms</a>" section. - </div><p> - The remainder of this section presents the basic steps used to create a BSP - based on an existing BSP that ships with the Yocto Project. - You can reference the "<a class="link" href="#dev-manual-bsp-appendix" title="Appendix A. BSP Development Example">BSP Development Example</a>" - appendix for a detailed example that uses the Crown Bay BSP as a base BSP from which to start. - </p><p> - The following illustration and list summarize the BSP creation general workflow. - </p><p> - </p><table border="0" summary="manufactured viewport for HTML img" cellspacing="0" cellpadding="0" width="540"><tr style="height: 630px"><td align="center"><img src="figures/bsp-dev-flow.png" align="middle" width="540" /></td></tr></table><p> - </p><p> - </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p><span class="emphasis"><em>Set up your host development system to support - development using the Yocto Project</em></span>: See the - "<a class="link" href="#the-linux-distro" target="_top">The Linux Distributions</a>" - and the - "<a class="link" href="#packages" target="_top">The Packages</a>" sections both - in the Yocto Project Quick Start for requirements.</p></li><li class="listitem"><p><span class="emphasis"><em>Establish a local copy of the project files on your - system</em></span>: You need this <a class="link" href="#source-directory">source - directory</a> available on your host system. - Having these files on your system gives you access to the build - process and to the tools you need. - For information on how to set up the source directory, see the - "<a class="link" href="#getting-setup" title="2.2. Getting Set Up">Getting Setup</a>" section.</p></li><li class="listitem"><p><span class="emphasis"><em>Establish a local copy of the base BSP files</em></span>: Having - the BSP files on your system gives you access to the build - process and to the tools you need for creating a BSP. - For information on how to get these files, see the - "<a class="link" href="#getting-setup" title="2.2. Getting Set Up">Getting Setup</a>" section.</p></li><li class="listitem"><p><span class="emphasis"><em>Choose a BSP that is supported by the Yocto Project - as your base BSP</em></span>: - The Yocto Project ships with several BSPs that support various hardware. - It is best to base your new BSP on an existing BSP rather than create all the - recipes and configuration files from scratch. - While it is possible to create everything from scratch, basing your new BSP - on something that is close is much easier. - Or, at a minimum, leveraging off an existing BSP - gives you some structure with which to start.</p><p>At this point you need to understand your target hardware well enough to determine which - existing BSP it most closely matches. - Things to consider are your hardware’s on-board features, such as CPU type and graphics support. - You should look at the README files for supported BSPs to get an idea of which one - you could use. - A generic <span class="trademark">Intel</span>® - <span class="trademark">Atom</span>™-based BSP to consider is the - Crown Bay that does not support the <span class="trademark">Intel</span>® - Embedded Media Graphics Driver (EMGD). - The remainder of this example uses that base BSP.</p><p>To see the supported BSPs, go to the - <a class="ulink" href="http://www.yoctoproject.org/download" target="_top">Download</a> page on the Yocto Project - website and click on “BSP Downloads.”</p></li><li class="listitem"><p><span class="emphasis"><em>Create your own BSP layer</em></span>: Layers are ideal for - isolating and storing work for a given piece of hardware. - A layer is really just a location or area in which you place the recipes for your BSP. - In fact, a BSP is, in itself, a special type of layer. - </p><p> - Another example that illustrates a layer is an application. - Suppose you are creating an application that has library or other dependencies in - order for it to compile and run. - The layer, in this case, would be where all the recipes that define those dependencies - are kept. - The key point for a layer is that it is an isolated area that contains - all the relevant information for the project that the OpenEmbedded build - system knows about. - For more information on layers, see the - "<a class="link" href="#understanding-and-creating-layers" title="4.1. Understanding and Creating Layers">Understanding and Creating Layers</a>" - section. - For more information on BSP layers, see the - "<a class="link" href="#bsp-layers" target="_top">BSP Layers</a>" section in the - Yocto Project Board Support Package (BSP) Developer's Guide.</p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>Four BSPs exist that are part of the - Yocto Project release: <code class="filename">atom-pc</code>, <code class="filename">beagleboard</code>, - <code class="filename">mpc8315e</code>, and <code class="filename">routerstationpro</code>. - The recipes and configurations for these four BSPs are located and dispersed - within the <a class="link" href="#source-directory">source directory</a>. - On the other hand, BSP layers for Crown Bay, Emenlow, Jasper Forest, - N450, Cedar Trail, Fish River, Fish River Island II, Romley, sys940x, tlk, - and Sugar Bay exist in their own separate layers within the larger - <code class="filename">meta-intel</code> layer.</div><p>When you set up a layer for a new BSP, you should follow a standard layout. - This layout is described in the section - "<a class="link" href="#bsp-filelayout" target="_top">Example Filesystem Layout</a>" - section of the Board Support Package (BSP) Development Guide. - In the standard layout, you will notice a suggested structure for recipes and - configuration information. - You can see the standard layout for the Crown Bay BSP in this example by examining the - directory structure of the <code class="filename">meta-crownbay</code> layer inside the - source directory.</p></li><li class="listitem"><p><span class="emphasis"><em>Make configuration changes to your new BSP - layer</em></span>: The standard BSP layer structure organizes the files you need - to edit in <code class="filename">conf</code> and several <code class="filename">recipes-*</code> - directories within the BSP layer. - Configuration changes identify where your new layer is on the local system - and identify which kernel you are going to use. - </p></li><li class="listitem"><p><span class="emphasis"><em>Make recipe changes to your new BSP layer</em></span>: Recipe - changes include altering recipes (<code class="filename">.bb</code> files), removing - recipes you don't use, and adding new recipes that you need to support your hardware. - </p></li><li class="listitem"><p><span class="emphasis"><em>Prepare for the build</em></span>: Once you have made all the - changes to your BSP layer, there remains a few things - you need to do for the OpenEmbedded build system in order for it to create your image. - You need to get the build environment ready by sourcing an environment setup script - and you need to be sure two key configuration files are configured appropriately.</p><p>The entire process for building an image is overviewed in the section - "<a class="link" href="#building-image" target="_top">Building an Image</a>" section - of the Yocto Project Quick Start. - You might want to reference this information.</p></li><li class="listitem"><p><span class="emphasis"><em>Build the image</em></span>: The OpenEmbedded build system - uses the BitBake tool to build images based on the type of image you want to create. - You can find more information on BitBake - <a class="ulink" href="http://docs.openembedded.org/bitbake/html/" target="_top">here</a>.</p><p>The build process supports several types of images to satisfy different needs. - See the - "<a class="link" href="#ref-images" target="_top">Images</a>" chapter - in the Yocto Project Reference Manual for information on - supported images.</p></li></ol></div><p> - </p><p> - You can view a video presentation on "Building Custom Embedded Images with Yocto" - at <a class="ulink" href="http://free-electrons.com/blog/elc-2011-videos" target="_top">Free Electrons</a>. - You can also find supplemental information in - <a class="ulink" href="http://www.yoctoproject.org/docs/1.3/bsp-guide/bsp-guide.html" target="_top"> - The Board Support Package (BSP) Development Guide</a>. - Finally, there is wiki page write up of the example also located - <a class="ulink" href="https://wiki.yoctoproject.org/wiki/Transcript:_creating_one_generic_Atom_BSP_from_another" target="_top"> - here</a> that you might find helpful. - </p></div><div class="section" title="5.1.2. Modifying the Kernel"><div class="titlepage"><div><div><h3 class="title"><a id="modifying-the-kernel"></a>5.1.2. <a id="kernel-spot"></a>Modifying the Kernel</h3></div></div></div><p> - Kernel modification involves changing the Yocto Project kernel, which could involve changing - configuration options as well as adding new kernel recipes. - Configuration changes can be added in the form of configuration fragments, while recipe - modification comes through the kernel's <code class="filename">recipes-kernel</code> area - in a kernel layer you create. - </p><p> - The remainder of this section presents a high-level overview of the Yocto Project - kernel architecture and the steps to modify the kernel. - For a complete discussion of the kernel, see the - Yocto Project Kernel Architecture and Use Manual. - You can reference the appendix - "<a class="link" href="#dev-manual-kernel-appendix" title="Appendix B. Kernel Modification Example">Kernel Modification Example</a>" - for a detailed example that changes the configuration of a kernel. - </p><div class="section" title="5.1.2.1. Kernel Overview"><div class="titlepage"><div><div><h4 class="title"><a id="kernel-overview"></a>5.1.2.1. Kernel Overview</h4></div></div></div><p> - Traditionally, when one thinks of a patched kernel, they think of a base kernel - source tree and a fixed structure that contains kernel patches. - The Yocto Project, however, employs mechanisms, that in a sense, result in a kernel source - generator. - By the end of this section, this analogy will become clearer. - </p><p> - You can find a web interface to the Yocto Project kernel source repositories at - <a class="ulink" href="http://git.yoctoproject.org" target="_top">http://git.yoctoproject.org</a>. - If you look at the interface, you will see to the left a grouping of - Git repositories titled "Yocto Linux Kernel." - Within this group, you will find several kernels supported by - the Yocto Project: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><span class="emphasis"><em><code class="filename">linux-yocto-2.6.34</code></em></span> - The - stable Yocto Project kernel that is based on the Linux 2.6.34 released kernel.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">linux-yocto-2.6.37</code></em></span> - The - stable Yocto Project kernel that is based on the Linux 2.6.37 released kernel.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">linux-yocto-3.0</code></em></span> - The stable - Yocto Project kernel that is based on the Linux 3.0 released kernel.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">linux-yocto-3.0-1.1.x</code></em></span> - The - stable Yocto Project kernel to use with the Yocto Project Release 1.1.x. This kernel - is based on the Linux 3.0 released kernel.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">linux-yocto-3.2</code></em></span> - The - stable Yocto Project kernel to use with the Yocto Project Release 1.2. This kernel - is based on the Linux 3.2 released kernel.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">linux-yocto-dev</code></em></span> - A development - kernel based on the latest upstream release candidate available.</p></li></ul></div><p> - </p><p> - The kernels are maintained using the Git revision control system - that structures them using the familiar "tree", "branch", and "leaf" scheme. - Branches represent diversions from general code to more specific code, while leaves - represent the end-points for a complete and unique kernel whose source files - when gathered from the root of the tree to the leaf accumulate to create the files - necessary for a specific piece of hardware and its features. - The following figure displays this concept: - </p><p> - </p><table border="0" summary="manufactured viewport for HTML img" cellspacing="0" cellpadding="0" width="540"><tr style="height: 540px"><td align="center"><img src="figures/kernel-overview-1.png" align="middle" /></td></tr></table><p> - </p><p> - - </p><p> - Within the figure, the "Kernel.org Branch Point" represents the point in the tree - where a supported base kernel is modified from the Linux kernel. - For example, this could be the branch point for the <code class="filename">linux-yocto-3.0</code> - kernel. - Thus, everything further to the right in the structure is based on the - <code class="filename">linux-yocto-3.0</code> kernel. - Branch points to right in the figure represent where the - <code class="filename">linux-yocto-3.0</code> kernel is modified for specific hardware - or types of kernels, such as real-time kernels. - Each leaf thus represents the end-point for a kernel designed to run on a specific - targeted device. - </p><p> - - </p><p> - The overall result is a Git-maintained repository from which all the supported - kernel types can be derived for all the supported devices. - A big advantage to this scheme is the sharing of common features by keeping them in - "larger" branches within the tree. - This practice eliminates redundant storage of similar features shared among kernels. - </p><p> - - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3> - Keep in mind the figure does not take into account all the supported Yocto - Project kernel types, but rather shows a single generic kernel just for conceptual purposes. - Also keep in mind that this structure represents the Yocto Project source repositories - that are either pulled from during the build or established on the host development system - prior to the build by either cloning a particular kernel's Git repository or by - downloading and unpacking a tarball. - </div><p> - - </p><p> - Storage of all the available kernel source code is one thing, while representing the - code on your host development system is another. - Conceptually, you can think of the kernel source repositories as all the - source files necessary for all the supported kernels. - As a developer, you are just interested in the source files for the kernel on - on which you are working. - And, furthermore, you need them available on your host system. - </p><p> - - </p><p> - You make kernel source code available on your host development system by using - Git to create a bare clone of the Yocto Project kernel Git repository - in which you are interested. - Then, you use Git again to clone a copy of that bare clone. - This copy represents the directory structure on your host system that is particular - to the kernel you want. - These are the files you actually modify to change the kernel. - See the <a class="link" href="#local-kernel-files">Yocto Project Kernel</a> item earlier - in this manual for an example of how to set up the kernel source directory - structure on your host system. - </p><p> - - </p><p> - This next figure illustrates how the kernel source files might be arranged on - your host system. - </p><p> - - </p><p> - </p><table border="0" summary="manufactured viewport for HTML img" cellspacing="0" cellpadding="0" width="540"><tr style="height: 360px"><td align="center"><img src="figures/kernel-overview-3-denzil.png" align="middle" /></td></tr></table><p> - </p><p> - - </p><p> - In the previous figure, the file structure on the left represents the bare clone - set up to track the Yocto Project kernel Git repository. - The structure on the right represents the copy of the bare clone. - When you make modifcations to the kernel source code, this is the area in which - you work. - Once you make corrections, you must use Git to push the committed changes to the - bare clone. - The example in <a class="xref" href="#modifying-the-kernel-source-code" title="B.1. Modifying the Kernel Source Code">Section B.1, “Modifying the Kernel Source Code”</a> provides a detailed example. - </p><p> - - </p><p> - What happens during the build? - When you build the kernel on your development system all files needed for the build - are taken from the source repositories pointed to by the - <code class="filename">SRC_URI</code> variable and gathered in a temporary work area - where they are subsequently used to create the unique kernel. - Thus, in a sense, the process constructs a local source tree specific to your - kernel to generate the new kernel image - a source generator if you will. - </p><p> - The following figure shows the temporary file structure - created on your host system when the build occurs. - This build directory contains all the source files used during the build. - </p><p> - </p><table border="0" summary="manufactured viewport for HTML img" cellspacing="0" cellpadding="0" width="540"><tr style="height: 450px"><td align="center"><img src="figures/kernel-overview-2.png" align="middle" /></td></tr></table><p> - </p><p> - Again, for a complete discussion of the Yocto Project kernel's architecture and its - branching strategy, see the - Yocto Project Kernel Architecture and Use Manual. - You can also reference the - "<a class="link" href="#modifying-the-kernel-source-code" title="B.1. Modifying the Kernel Source Code">Modifying the Kernel Source Code</a>" - section for a detailed example that modifies the kernel. - </p></div><div class="section" title="5.1.2.2. Kernel Modification Workflow"><div class="titlepage"><div><div><h4 class="title"><a id="kernel-modification-workflow"></a>5.1.2.2. Kernel Modification Workflow</h4></div></div></div><p> - This illustration and the following list summarizes the kernel modification general workflow. - </p><p> - </p><table border="0" summary="manufactured viewport for HTML img" cellspacing="0" cellpadding="0" width="540"><tr style="height: 675px"><td align="center"><img src="figures/kernel-dev-flow.png" align="middle" width="540" /></td></tr></table><p> - </p><p> - </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p><span class="emphasis"><em>Set up your host development system to support - development using the Yocto Project</em></span>: See - "<a class="link" href="#the-linux-distro" target="_top">The Linux Distributions</a>" and - "<a class="link" href="#packages" target="_top">The Packages</a>" sections both - in the Yocto Project Quick Start for requirements.</p></li><li class="listitem"><p><span class="emphasis"><em>Establish a local copy of project files on your - system</em></span>: Having the <a class="link" href="#source-directory">source - directory</a> on your system gives you access to the build process and tools - you need. - For information on how to get these files, see the bulleted item - "<a class="link" href="#local-yp-release">Yocto Project Release</a>" earlier in this manual. - </p></li><li class="listitem"><p><span class="emphasis"><em>Set up a local copy of the <code class="filename">poky-extras</code> Git - repository</em></span>: This local repository is the area for your configuration - fragments, new kernel recipes, and the kernel <code class="filename">.bbappend</code> - file used during the build. - It is good practice to set this repository up inside your local - source directory. - For information on how to get these files, see the bulleted item - "<a class="link" href="#poky-extras-repo">The <code class="filename">poky-extras</code> Git Repository</a>" - earlier in this manual. - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>While it is certainly possible to modify the kernel without involving - a local Git repository, the suggested workflow for kernel modification - using the Yocto Project does use a Git repository.</div></li><li class="listitem"><p><span class="emphasis"><em>Establish a local copy of the Yocto Project kernel files on your - system</em></span>: In order to make modifications to the kernel you need two things: - a bare clone of the Yocto Project kernel you are modifying and - a copy of that bare clone. - The bare clone is required by the build process and is the area to which you - push your kernel source changes (pulling does not work with bare clones). - The copy of the bare clone is a local Git repository that contains all the kernel's - source files. - You make your changes to the files in this copy of the bare clone. - For information on how to set these two items up, see the bulleted item - "<a class="link" href="#local-kernel-files">Yocto Project Kernel</a>" - earlier in this manual.</p></li><li class="listitem"><p><span class="emphasis"><em>Make changes to the kernel source code if - applicable</em></span>: Modifying the kernel does not always mean directly - changing source files. - However, if you have to do this, you make the changes in the local - Git repository you set up to hold the source files (i.e. the copy of the - bare clone). - Once the changes are made, you need to use Git commands to commit the changes - and then push them to the bare clone.</p></li><li class="listitem"><p><span class="emphasis"><em>Make kernel configuration changes - if applicable</em></span>: - If your situation calls for changing the kernel's configuration, you can - use <code class="filename">menuconfig</code> - to enable and disable kernel configurations. - Using <code class="filename">menuconfig</code> allows you to interactively develop and test the - configuration changes you are making to the kernel. - When saved, changes using <code class="filename">menuconfig</code> update the kernel's - <code class="filename">.config</code>. - Try to resist the temptation of directly editing the <code class="filename">.config</code> - file found in the - <a class="link" href="#build-directory">build directory</a> at - <code class="filename">tmp/sysroots/<machine-name>/kernel</code>. - Doing so, can produce unexpected results when the OpenEmbedded build system - regenerates the configuration file.</p><p>Once you are satisfied with the configuration changes made using - <code class="filename">menuconfig</code>, you can directly examine the - <code class="filename">.config</code> file against a saved original and gather those - changes into a config fragment to be referenced from within the kernel's - <code class="filename">.bbappend</code> file.</p></li><li class="listitem"><p><span class="emphasis"><em>Add or extend kernel recipes if applicable</em></span>: - The standard - layer structure organizes recipe files inside the - <code class="filename">meta-kernel-dev</code> layer that is within the local - <code class="filename">poky-extras</code> Git repository. - If you need to add new kernel recipes, you add them within this layer. - Also within this area, you will find the <code class="filename">.bbappend</code> - file that appends information to the kernel's recipe file used during the - build. - </p></li><li class="listitem"><p><span class="emphasis"><em>Prepare for the build</em></span>: Once you have made all the - changes to your kernel (configurations, source code changes, recipe additions, - or recipe changes), there remains a few things - you need to do in order for the build system to create your image. - If you have not done so, you need to get the build environment ready by sourcing - the environment setup script described earlier. - You also need to be sure two key configuration files - (<code class="filename">local.conf</code> and <code class="filename">bblayers.conf</code>) - are configured appropriately.</p><p>The entire process for building an image is overviewed in the - "<a class="link" href="#building-image" target="_top">Building an Image</a>" - section of the Yocto Project Quick Start. - You might want to reference this information. - Also, you should look at the detailed examples found in the appendices at - at the end of this manual.</p></li><li class="listitem"><p><span class="emphasis"><em>Build the image</em></span>: The OpenEmbedded - build system uses the BitBake - tool to build images based on the type of image you want to create. - You can find more information on BitBake - <a class="ulink" href="http://docs.openembedded.org/bitbake/html/" target="_top">here</a>.</p><p>The build process supports several types of images to satisfy different needs. - See the "<a class="link" href="#ref-images" target="_top">Images</a>" chapter in - the Yocto Project Reference Manual for information on supported images.</p></li><li class="listitem"><p><span class="emphasis"><em>Make your configuration changes available - in the kernel layer</em></span>: Up to this point, all the configuration changes to the - kernel have been done and tested iteratively. - Once they are tested and ready to go, you can move them into the kernel layer, - which allows you to distribute the layer.</p></li><li class="listitem"><p><span class="emphasis"><em>If applicable, share your in-tree changes</em></span>: - If the changes you made - are suited for all Yocto Project kernel users, you might want to send them on - for inclusion into the upstream kernel's Git repository. - If the changes are accepted, the Yocto Project Maintainer pulls them into - the master branch of the kernel tree. - Doing so makes them available to everyone using the kernel.</p></li></ol></div><p> - </p></div></div></div><div class="section" title="5.2. Application Development Workflow"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="application-development-workflow"></a>5.2. Application Development Workflow</h2></div></div></div><p> - Application development involves creating an application that you want - to run on your target hardware, which is running a kernel image created using the - OpenEmbedded build system. - The Yocto Project provides an Application Development Toolkit (ADT) and - stand-alone cross-development toolchains that - facilitate quick development and integration of your application into its run-time environment. - Using the ADT and toolchains, you can compile and link your application. - You can then deploy your application to the actual hardware or to the QEMU emulator for testing. - If you are familiar with the popular Eclipse IDE, you can use an Eclipse Yocto Plug-in to - allow you to develop, deploy, and test your application all from within Eclipse. - </p><p> - While we strongly suggest using the ADT to develop your application, this option might not - be best for you. - If this is the case, you can still use pieces of the Yocto Project for your development process. - However, because the process can vary greatly, this manual does not provide detail on the process. - </p><div class="section" title="5.2.1. Workflow Using the ADT and Eclipse™"><div class="titlepage"><div><div><h3 class="title"><a id="workflow-using-the-adt-and-eclipse"></a>5.2.1. Workflow Using the ADT and <span class="trademark">Eclipse</span>™</h3></div></div></div><p> - To help you understand how application development works using the ADT, this section - provides an overview of the general development process and a detailed example of the process - as it is used from within the Eclipse IDE. - </p><p> - The following illustration and list summarize the application development general workflow. - </p><p> - </p><table border="0" summary="manufactured viewport for HTML img" cellspacing="0" cellpadding="0" width="630"><tr style="height: 720px"><td align="center"><img src="figures/app-dev-flow.png" align="middle" /></td></tr></table><p> - </p><p> - </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p><span class="emphasis"><em>Prepare the Host System for the Yocto Project</em></span>: - See - "<a class="link" href="#the-linux-distro" target="_top">The Linux Distributions</a>" and - "<a class="link" href="#packages" target="_top">The Packages</a>" sections both - in the Yocto Project Quick Start for requirements.</p></li><li class="listitem"><p><span class="emphasis"><em>Secure the Yocto Project Kernel Target Image</em></span>: - You must have a target kernel image that has been built using the OpenEmbeded - build system.</p><p>Depending on whether the Yocto Project has a pre-built image that matches your target - architecture and where you are going to run the image while you develop your application - (QEMU or real hardware), the area from which you get the image differs. - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>Download the image from - <a class="ulink" href="http://downloads.yoctoproject.org/releases/yocto/yocto-1.3/machines" target="_top"> - <code class="filename">machines</code></a> if your target architecture is supported - and you are going to develop and test your application on actual hardware. - </p></li><li class="listitem"><p>Download the image from the - <a class="ulink" href="http://downloads.yoctoproject.org/releases/yocto/yocto-1.3/machines/qemu" target="_top"> - <code class="filename">machines/qemu</code></a> if your target architecture is supported - and you are going to develop and test your application using the QEMU - emulator.</p></li><li class="listitem"><p>Build your image if you cannot find a pre-built image that matches - your target architecture. - If your target architecture is similar to a supported architecture, you can - modify the kernel image before you build it. - See the - "<a class="link" href="#kernel-modification-workflow" title="5.1.2.2. Kernel Modification Workflow">Kernel Modification Workflow</a>" - section earlier in this manual for information on how to create a modified - Yocto Project kernel.</p></li></ul></div><p>For information on pre-built kernel image naming schemes for images - that can run on the QEMU emulator, see the - "<a class="link" href="#downloading-the-pre-built-linux-kernel" target="_top">Downloading the Pre-Built Linux Kernel</a>" - section in the Yocto Project Quick Start.</p></li><li class="listitem"><p><span class="emphasis"><em>Install the ADT</em></span>: - The ADT provides a target-specific cross-development toolchain, the root filesystem, - the QEMU emulator, and other tools that can help you develop your application. - While it is possible to get these pieces separately, the ADT Installer provides an - easy method. - You can get these pieces by running an ADT installer script, which is configurable. - For information on how to install the ADT, see the - "<a class="link" href="#using-the-adt-installer" target="_top">Using the ADT Installer</a>" - section - in the Yocto Project Application Developer's Guide.</p></li><li class="listitem"><p><span class="emphasis"><em>If Applicable, Secure the Target Root Filesystem</em></span>: - If you choose not to install the ADT using the ADT Installer, - you need to find and download the - appropriate root filesystems. - You can find these tarballs in the same areas used for the kernel images. - Depending on the type of image you are running, the root filesystem you need differs. - For example, if you are developing an application that runs on an image that - supports Sato, you need to get root filesystem that supports Sato. - </p></li><li class="listitem"><p><span class="emphasis"><em>Create and Build your Application</em></span>: - At this point, you need to have source files for your application. - Once you have the files, you can use the Eclipse IDE to import them and build the - project. - If you are not using Eclipse, you need to use the cross-development tools you have - installed to create the image.</p></li><li class="listitem"><p><span class="emphasis"><em>Deploy the Image with the Application</em></span>: - If you are using the Eclipse IDE, you can deploy your image to the hardware or to - QEMU through the project's preferences. - If you are not using the Eclipse IDE, then you need to deploy the application using - other methods to the hardware. - Or, if you are using QEMU, you need to use that tool and load your image in for testing. - </p></li><li class="listitem"><p><span class="emphasis"><em>Test and Debug the Application</em></span>: - Once your application is deployed, you need to test it. - Within the Eclipse IDE, you can use the debubbing environment along with the - set of user-space tools installed along with the ADT to debug your application. - Of course, the same user-space tools are available separately if you choose - not to use the Eclipse IDE.</p></li></ol></div><p> - </p></div><div class="section" title="5.2.2. Working Within Eclipse"><div class="titlepage"><div><div><h3 class="title"><a id="adt-eclipse"></a>5.2.2. Working Within Eclipse</h3></div></div></div><p> - The Eclipse IDE is a popular development environment and it fully supports - development using the Yocto Project. - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>This release of the Yocto Project supports both the Juno and Indigo versions - of the Eclipse IDE. - Thus, the following information provides setup information for both versions. - </div><p> - </p><p> - When you install and configure the Eclipse Yocto Project Plug-in into - the Eclipse IDE, you maximize your Yocto Project experience. - Installing and configuring the Plug-in results in an environment that - has extensions specifically designed to let you more easily develop software. - These extensions allow for cross-compilation, deployment, and execution of - your output into a QEMU emulation session. - You can also perform cross-debugging and profiling. - The environment also supports a suite of tools that allows you to perform - remote profiling, tracing, collection of power data, collection of - latency data, and collection of performance data. - </p><p> - This section describes how to install and configure the Eclipse IDE - Yocto Plug-in and how to use it to develop your application. - </p><div class="section" title="5.2.2.1. Setting Up the Eclipse IDE"><div class="titlepage"><div><div><h4 class="title"><a id="setting-up-the-eclipse-ide"></a>5.2.2.1. Setting Up the Eclipse IDE</h4></div></div></div><p> - To develop within the Eclipse IDE, you need to do the following: - </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Install the optimal version of the Eclipse IDE.</p></li><li class="listitem"><p>Configure the Eclipse IDE.</p></li><li class="listitem"><p>Install the Eclipse Yocto Plug-in.</p></li><li class="listitem"><p>Configure the Eclipse Yocto Plug-in.</p></li></ol></div><p> - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3> - Do not install Eclipse from your distribution's package repository. - Be sure to install Eclipse from the official Eclipse download site as directed - in the next section. - </div><p> - </p><div class="section" title="5.2.2.1.1. Installing the Eclipse IDE"><div class="titlepage"><div><div><h5 class="title"><a id="installing-eclipse-ide"></a>5.2.2.1.1. Installing the Eclipse IDE</h5></div></div></div><p> - It is recommended that you have the Juno 4.2 version of the - Eclipse IDE installed on your development system. - However, if you currently have the Indigo 3.7.2 version installed and you do - not want to upgrade the IDE, you can configure Indigo to work with the - Yocto Project. - See the - "<a class="link" href="#configuring-the-eclipse-ide-indigo" title="5.2.2.1.3. Configuring the Eclipse IDE (Indigo)">Configuring the Eclipse IDE (Indigo)</a>" - section. - </p><p> - If you don’t have the Juno 4.2 Eclipse IDE installed, you can find the tarball at - <a class="ulink" href="http://www.eclipse.org/downloads" target="_top">http://www.eclipse.org/downloads</a>. - From that site, choose the Eclipse Classic version particular to your development - host. - This version contains the Eclipse Platform, the Java Development - Tools (JDT), and the Plug-in Development Environment. - </p><p> - Once you have downloaded the tarball, extract it into a clean - directory. - For example, the following commands unpack and install the Eclipse IDE - tarball found in the <code class="filename">Downloads</code> area - into a clean directory using the default name <code class="filename">eclipse</code>: - </p><pre class="literallayout"> - $ cd ~ - $ tar -xzvf ~/Downloads/eclipse-SDK-4.2-linux-gtk-x86_64.tar.gz - </pre><p> - </p><p> - If you have the Indigo 3.7.2 Eclipse IDE already installed and you want to use that - version, one issue exists that you need to be aware of regarding the Java - Virtual machine’s garbage collection (GC) process. - The GC process does not clean up the permanent generation - space (PermGen). - This space stores metadata descriptions of classes. - The default value is set too small and it could trigger an - out-of-memory error such as the following: - </p><pre class="literallayout"> - Java.lang.OutOfMemoryError: PermGen space - </pre><p> - </p><p> - This error causes the application to hang. - </p><p> - To fix this issue, you can use the <code class="filename">--vmargs</code> - option when you start the Indigo 3.7.2 Eclipse IDE - to increase the size of the permanent generation space: - </p><pre class="literallayout"> - eclipse --vmargs --XX:PermSize=256M - </pre><p> - </p></div><div class="section" title="5.2.2.1.2. Configuring the Eclipse IDE (Juno)"><div class="titlepage"><div><div><h5 class="title"><a id="configuring-the-eclipse-ide-juno"></a>5.2.2.1.2. Configuring the Eclipse IDE (Juno)</h5></div></div></div><p> - This section presents the steps needed to configure the Juno 4.2 Eclipse IDE. - If you are using Indigo 3.7.2, see the - "<a class="link" href="#configuring-the-eclipse-ide-indigo" title="5.2.2.1.3. Configuring the Eclipse IDE (Indigo)">Configuring the Eclipse IDE (Indigo)</a>". - </p><p> - Before installing and configuring the Eclipse Yocto Plug-in, you need to configure - the Juno 4.2 Eclipse IDE. - Follow these general steps: - </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Start the Eclipse IDE.</p></li><li class="listitem"><p>Make sure you are in your Workbench and select - "Install New Software" from the "Help" pull-down menu. - </p></li><li class="listitem"><p>Select <code class="filename">Juno - http://download.eclipse.org/releases/juno</code> - from the "Work with:" pull-down menu.</p></li><li class="listitem"><p>Expand the box next to "Linux Tools" and select the - "LTTng - Linux Tracing Toolkit" boxes.</p></li><li class="listitem"><p>Expand the box next to "Mobile and Device Development" and select the - following boxes: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><code class="filename">C/C++ Remote Launch</code></p></li><li class="listitem"><p><code class="filename">Remote System Explorer End-user Runtime</code></p></li><li class="listitem"><p><code class="filename">Remote System Explorer User Actions</code></p></li><li class="listitem"><p><code class="filename">Target Management Terminal</code></p></li><li class="listitem"><p><code class="filename">TCF Remote System Explorer add-in</code></p></li><li class="listitem"><p><code class="filename">TCF Target Explorer</code></p></li></ul></div></li><li class="listitem"><p>Expand the box next to <code class="filename">Programming Languages</code> - and select the <code class="filename">Autotools Support for CDT</code> - and <code class="filename">C/C++ Development Tools</code> boxes.</p></li><li class="listitem"><p>Complete the installation and restart the Eclipse IDE.</p></li></ol></div><p> - </p></div><div class="section" title="5.2.2.1.3. Configuring the Eclipse IDE (Indigo)"><div class="titlepage"><div><div><h5 class="title"><a id="configuring-the-eclipse-ide-indigo"></a>5.2.2.1.3. Configuring the Eclipse IDE (Indigo)</h5></div></div></div><p> - This section presents the steps needed to configure the Indigo 3.7.2 Eclipse IDE. - If you are using Juno 4.2, see the - "<a class="link" href="#configuring-the-eclipse-ide-juno" title="5.2.2.1.2. Configuring the Eclipse IDE (Juno)">Configuring the Eclipse IDE (Juno)</a>". - </p><p> - Before installing and configuring the Eclipse Yocto Plug-in, you need to configure - the Indigo 3.7.2 Eclipse IDE. - Follow these general steps: - </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Start the Eclipse IDE.</p></li><li class="listitem"><p>Make sure you are in your Workbench and select - "Install New Software" from the "Help" pull-down menu. - </p></li><li class="listitem"><p>Select <code class="filename">indigo - http://download.eclipse.org/releases/indigo</code> - from the "Work with:" pull-down menu.</p></li><li class="listitem"><p>Expand the box next to <code class="filename">Programming Languages</code> - and select the <code class="filename">Autotools Support for CDT (incubation)</code> - and <code class="filename">C/C++ Development Tools</code> boxes.</p></li><li class="listitem"><p>Expand the box next to "Linux Tools" and select the - "LTTng - Linux Tracing Toolkit(incubation)" boxes.</p></li><li class="listitem"><p>Complete the installation and restart the Eclipse IDE.</p></li><li class="listitem"><p>After the Eclipse IDE restarts and from the Workbench, select - "Install New Software" from the "Help" pull-down menu.</p></li><li class="listitem"><p>Click the - "Available Software Sites" link.</p></li><li class="listitem"><p>Check the box next to - <code class="filename">http://download.eclipse.org/tm/updates/3.3</code> - and click "OK".</p></li><li class="listitem"><p>Select <code class="filename">http://download.eclipse.org/tm/updates/3.3</code> - from the "Work with:" pull-down menu.</p></li><li class="listitem"><p>Check the box next to <code class="filename">TM and RSE Main Features</code>. - </p></li><li class="listitem"><p>Expand the box next to <code class="filename">TM and RSE Optional Add-ons</code> - and select every item except <code class="filename">RSE Unit Tests</code> and - <code class="filename">RSE WinCE Services (incubation)</code>.</p></li><li class="listitem"><p>Complete the installation and restart the Eclipse IDE.</p></li><li class="listitem"><p>If necessary, select - "Install New Software" from the "Help" pull-down menu so you can click the - "Available Software Sites" link again.</p></li><li class="listitem"><p>After clicking "Available Software Sites", check the box next to - <code class="filename">http://download.eclipse.org/tools/cdt/releases/indigo</code> - and click "OK".</p></li><li class="listitem"><p>Select <code class="filename">http://download.eclipse.orgtools/cdt/releases/indigo</code> - from the "Work with:" pull-down menu.</p></li><li class="listitem"><p>Check the box next to <code class="filename">CDT Main Features</code>. - </p></li><li class="listitem"><p>Expand the box next to <code class="filename">CDT Optional Features</code> - and select <code class="filename">C/C++ Remote Launch</code> and - <code class="filename">Target Communication Framework (incubation)</code>.</p></li><li class="listitem"><p>Complete the installation and restart the Eclipse IDE.</p></li></ol></div><p> - </p></div><div class="section" title="5.2.2.1.4. Installing or Accessing the Eclipse Yocto Plug-in"><div class="titlepage"><div><div><h5 class="title"><a id="installing-the-eclipse-yocto-plug-in"></a>5.2.2.1.4. Installing or Accessing the Eclipse Yocto Plug-in</h5></div></div></div><p> - You can install the Eclipse Yocto Plug-in into the Eclipse IDE - one of two ways: use the Yocto Project's Eclipse Update site to install the pre-built plug-in, - or build and install the plug-in from the latest source code. - If you don't want to permanently install the plug-in but just want to try it out - within the Eclipse environment, you can import the plug-in project from the - Yocto Project source repositories. - </p><div class="section" title="5.2.2.1.4.1. Installing the Pre-built Plug-in from the Yocto Project Eclipse Update Site"><div class="titlepage"><div><div><h6 class="title"><a id="new-software"></a>5.2.2.1.4.1. Installing the Pre-built Plug-in from the Yocto Project Eclipse Update Site</h6></div></div></div><p> - To install the Eclipse Yocto Plug-in from the update site, - follow these steps: - </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Start up the Eclipse IDE.</p></li><li class="listitem"><p>In Eclipse, select "Install New Software" from the "Help" menu.</p></li><li class="listitem"><p>Click "Add..." in the "Work with:" area.</p></li><li class="listitem"><p>Enter - <code class="filename">http://downloads.yoctoproject.org/releases/eclipse-plugin/1.3</code> - in the URL field and provide a meaningful name in the "Name" field.</p></li><li class="listitem"><p>Click "OK" to have the entry added to the "Work with:" - drop-down list.</p></li><li class="listitem"><p>Select the entry for the plug-in from the "Work with:" drop-down - list.</p></li><li class="listitem"><p>Check the box next to <code class="filename">Development tools and SDKs for Yocto Linux</code>. - </p></li><li class="listitem"><p>Complete the remaining software installation steps and - then restart the Eclipse IDE to finish the installation of the plug-in. - </p></li></ol></div><p> - </p></div><div class="section" title="5.2.2.1.4.2. Installing the Plug-in Using the Latest Source Code"><div class="titlepage"><div><div><h6 class="title"><a id="zip-file-method"></a>5.2.2.1.4.2. Installing the Plug-in Using the Latest Source Code</h6></div></div></div><p> - To install the Eclipse Yocto Plug-in from the latest source code, follow these steps: - </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Open a shell and create a Git repository with: - </p><pre class="literallayout"> - $ git clone git://git.yoctoproject.org/eclipse-poky yocto-eclipse - </pre><p> - For this example, the repository is named - <code class="filename">~/yocto-eclipse</code>.</p></li><li class="listitem"><p>Locate the <code class="filename">build.sh</code> script in the - Git repository you created in the previous step. - The script is located in the <code class="filename">scripts</code>.</p></li><li class="listitem"><p>Be sure to set and export the <code class="filename">ECLIPSE_HOME</code> environment - variable to the top-level directory in which you installed the Indigo - version of Eclipse. - For example, if your Eclipse directory is <code class="filename">$HOME/eclipse</code>, - use the following: - </p><pre class="literallayout"> - $ export ECLIPSE_HOME=$HOME/eclipse - </pre></li><li class="listitem"><p>Run the <code class="filename">build.sh</code> script and provide the - name of the Git branch along with the Yocto Project release you are - using. - Here is an example that uses the <code class="filename">master</code> Git repository - and the <code class="filename">1.1M4</code> release: - </p><pre class="literallayout"> - $ scripts/build.sh master 1.1M4 - </pre><p> - After running the script, the file - <code class="filename">org.yocto.sdk-<release>-<date>-archive.zip</code> - is in the current directory.</p></li><li class="listitem"><p>If necessary, start the Eclipse IDE and be sure you are in the - Workbench.</p></li><li class="listitem"><p>Select "Install New Software" from the "Help" pull-down menu. - </p></li><li class="listitem"><p>Click "Add".</p></li><li class="listitem"><p>Provide anything you want in the "Name" field.</p></li><li class="listitem"><p>Click "Archive" and browse to the ZIP file you built - in step four. - This ZIP file should not be "unzipped", and must be the - <code class="filename">*archive.zip</code> file created by running the - <code class="filename">build.sh</code> script.</p></li><li class="listitem"><p>Check the box next to the new entry in the installation window and complete - the installation.</p></li><li class="listitem"><p>Restart the Eclipse IDE if necessary.</p></li></ol></div><p> - </p><p> - At this point you should be able to configure the Eclipse Yocto Plug-in as described in the - "<a class="link" href="#configuring-the-eclipse-yocto-plug-in" title="5.2.2.1.5. Configuring the Eclipse Yocto Plug-in">Configuring the Eclipse Yocto Plug-in</a>" - section.</p></div><div class="section" title="5.2.2.1.4.3. Importing the Plug-in Project into the Eclipse Environment"><div class="titlepage"><div><div><h6 class="title"><a id="yocto-project-source"></a>5.2.2.1.4.3. Importing the Plug-in Project into the Eclipse Environment</h6></div></div></div><p> - Importing the Eclipse Yocto Plug-in project from the Yocto Project source repositories - is useful when you want to try out the latest plug-in from the tip of plug-in's - development tree. - It is important to understand when you import the plug-in you are not installing - it into the Eclipse application. - Rather, you are importing the project and just using it. - To import the plug-in project, follow these steps: - </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Open a shell and create a Git repository with: - </p><pre class="literallayout"> - $ git clone git://git.yoctoproject.org/eclipse-poky yocto-eclipse - </pre><p> - For this example, the repository is named - <code class="filename">~/yocto-eclipse</code>.</p></li><li class="listitem"><p>In Eclipse, select "Import" from the "File" menu.</p></li><li class="listitem"><p>Expand the "General" box and select "existing projects into workspace" - and then click "Next".</p></li><li class="listitem"><p>Select the root directory and browse to - <code class="filename">~/yocto-eclipse/plugins</code>.</p></li><li class="listitem"><p>Three plug-ins exist: "org.yocto.bc.ui", "org.yocto.sdk.ide", and - "org.yocto.sdk.remotetools". - Select and import all of them.</p></li></ol></div><p> - </p><p> - The left navigation pane in the Eclipse application shows the default projects. - Right-click on one of these projects and run it as an Eclipse application. - This brings up a second instance of Eclipse IDE that has the Yocto Plug-in. - </p></div></div><div class="section" title="5.2.2.1.5. Configuring the Eclipse Yocto Plug-in"><div class="titlepage"><div><div><h5 class="title"><a id="configuring-the-eclipse-yocto-plug-in"></a>5.2.2.1.5. Configuring the Eclipse Yocto Plug-in</h5></div></div></div><p> - Configuring the Eclipse Yocto Plug-in involves setting the Cross - Compiler options and the Target options. - The configurations you choose become the default settings for all projects. - You do have opportunities to change them later when - you configure the project (see the following section). - </p><p> - To start, you need to do the following from within the Eclipse IDE: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>Choose <code class="filename">Windows -> Preferences</code> to display - the <code class="filename">Preferences</code> Dialog</p></li><li class="listitem"><p>Click <code class="filename">Yocto Project ADT</code></p></li></ul></div><p> - </p><div class="section" title="5.2.2.1.5.1. Configuring the Cross-Compiler Options"><div class="titlepage"><div><div><h6 class="title"><a id="configuring-the-cross-compiler-options"></a>5.2.2.1.5.1. Configuring the Cross-Compiler Options</h6></div></div></div><p> - To configure the Cross Compiler Options, you must select the type of toolchain, - point to the toolchain, specify the sysroot location, and select the target architecture. - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><span class="emphasis"><em>Selecting the Toolchain Type:</em></span> - Choose between <code class="filename">Standalone pre-built toolchain</code> - and <code class="filename">Build system derived toolchain</code> for Cross - Compiler Options. - </p><div class="itemizedlist"><ul class="itemizedlist" type="circle"><li class="listitem"><p><span class="emphasis"><em> - <code class="filename">Standalone Pre-built Toolchain:</code></em></span> - Select this mode when you are using a stand-alone cross-toolchain. - For example, suppose you are an application developer and do not - need to build a target image. - Instead, you just want to use an architecture-specific toolchain on an - existing kernel and target root filesystem. - </p></li><li class="listitem"><p><span class="emphasis"><em> - <code class="filename">Build System Derived Toolchain:</code></em></span> - Select this mode if the cross-toolchain has been installed and built - as part of the build directory. - When you select <code class="filename">Build system derived toolchain</code>, - you are using the toolchain bundled - inside the build directory. - </p></li></ul></div><p> - </p></li><li class="listitem"><p><span class="emphasis"><em>Point to the Toolchain:</em></span> - If you are using a stand-alone pre-built toolchain, you should be pointing to the - <code class="filename">/opt/poky/1.3</code> directory. - This is the location for toolchains installed by the ADT Installer or by hand. - Sections "<a class="link" href="#configuring-and-running-the-adt-installer-script" target="_top">Configuring - and Running the ADT Installer Script</a>" and - "<a class="link" href="#using-an-existing-toolchain-tarball" target="_top">Using a Cross-Toolchain Tarball</a>" - in the Yocto Project Application Developer's Guide - describe two ways to install a stand-alone cross-toolchain in the - <code class="filename">/opt/poky</code> directory. - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>It is possible to install a stand-alone cross-toolchain in a directory - other than <code class="filename">/opt/poky</code>. - However, doing so is discouraged.</div><p>If you are using a system-derived toolchain, the path you provide - for the <code class="filename">Toolchain Root Location</code> - field is the build directory. - See the "<a class="link" href="#using-the-toolchain-from-within-the-build-tree" target="_top">Using - BitBake and the build directory</a>" section in the Yocto Project Application - Developer's Guide for information on how to install the toolchain into the build -directory.</p></li><li class="listitem"><p><span class="emphasis"><em>Specify the Sysroot Location:</em></span> - This location is where the root filesystem for the - target hardware is created on the development system by the ADT Installer. - The QEMU user-space tools, the - NFS boot process, and the cross-toolchain all use the sysroot location. - </p></li><li class="listitem"><p><span class="emphasis"><em>Select the Target Architecture:</em></span> - The target architecture is the type of hardware you are - going to use or emulate. - Use the pull-down <code class="filename">Target Architecture</code> menu to make - your selection. - The pull-down menu should have the supported architectures. - If the architecture you need is not listed in the menu, you - will need to build the image. - See the "<a class="link" href="#building-image" target="_top">Building an Image</a>" section - of the Yocto Project Quick Start for more information.</p></li></ul></div><p> - </p></div><div class="section" title="5.2.2.1.5.2. Configuring the Target Options"><div class="titlepage"><div><div><h6 class="title"><a id="configuring-the-target-options"></a>5.2.2.1.5.2. Configuring the Target Options</h6></div></div></div><p> - You can choose to emulate hardware using the QEMU emulator, or you - can choose to run your image on actual hardware. - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><span class="emphasis"><em><code class="filename">QEMU:</code></em></span> Select this option if - you will be using the QEMU emulator. - If you are using the emulator, you also need to locate the kernel - and specify any custom options.</p><p>If you selected <code class="filename">Build system derived toolchain</code>, - the target kernel you built will be located in the - build directory in <code class="filename">tmp/deploy/images</code> directory. - If you selected <code class="filename">Standalone pre-built toolchain</code>, the - pre-built image you downloaded is located - in the directory you specified when you downloaded the image.</p><p>Most custom options are for advanced QEMU users to further - customize their QEMU instance. - These options are specified between paired angled brackets. - Some options must be specified outside the brackets. - In particular, the options <code class="filename">serial</code>, - <code class="filename">nographic</code>, and <code class="filename">kvm</code> must all - be outside the brackets. - Use the <code class="filename">man qemu</code> command to get help on all the options - and their use. - The following is an example: - </p><pre class="literallayout"> - serial ‘<-m 256 -full-screen>’ - </pre><p> - Regardless of the mode, Sysroot is already defined as part of the - Cross Compiler Options configuration in the - <code class="filename">Sysroot Location:</code> field.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">External HW:</code></em></span> Select this option - if you will be using actual hardware.</p></li></ul></div><p> - </p><p> - Click the <code class="filename">OK</code> button to save your plug-in configurations. - </p></div></div></div><div class="section" title="5.2.2.2. Creating the Project"><div class="titlepage"><div><div><h4 class="title"><a id="creating-the-project"></a>5.2.2.2. Creating the Project</h4></div></div></div><p> - You can create two types of projects: Autotools-based, or Makefile-based. - This section describes how to create Autotools-based projects from within - the Eclipse IDE. - For information on creating Makefile-based projects in a terminal window, see the section - "<a class="link" href="#using-the-command-line" target="_top">Using the Command Line</a>" - in the Yocto Project Application Developer's Guide. - </p><p> - To create a project based on a Yocto template and then display the source code, - follow these steps: - </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Select <code class="filename">File -> New -> Project</code>.</p></li><li class="listitem"><p>Double click <code class="filename">CC++</code>.</p></li><li class="listitem"><p>Double click <code class="filename">C Project</code> to create the project.</p></li><li class="listitem"><p>Expand <code class="filename">Yocto Project ADT Project</code>.</p></li><li class="listitem"><p>Select <code class="filename">Hello World ANSI C Autotools Project</code>. - This is an Autotools-based project based on a Yocto template.</p></li><li class="listitem"><p>Put a name in the <code class="filename">Project name:</code> field. - Do not use hyphens as part of the name.</p></li><li class="listitem"><p>Click <code class="filename">Next</code>.</p></li><li class="listitem"><p>Add information in the <code class="filename">Author</code> and - <code class="filename">Copyright notice</code> fields.</p></li><li class="listitem"><p>Be sure the <code class="filename">License</code> field is correct.</p></li><li class="listitem"><p>Click <code class="filename">Finish</code>.</p></li><li class="listitem"><p>If the "open perspective" prompt appears, click "Yes" so that you - in the C/C++ perspective.</p></li><li class="listitem"><p>The left-hand navigation pane shows your project. - You can display your source by double clicking the project's source file. - </p></li></ol></div><p> - </p></div><div class="section" title="5.2.2.3. Configuring the Cross-Toolchains"><div class="titlepage"><div><div><h4 class="title"><a id="configuring-the-cross-toolchains"></a>5.2.2.3. Configuring the Cross-Toolchains</h4></div></div></div><p> - The earlier section, "<a class="link" href="#configuring-the-eclipse-yocto-plug-in" title="5.2.2.1.5. Configuring the Eclipse Yocto Plug-in">Configuring - the Eclipse Yocto Plug-in</a>", sets up the default project - configurations. - You can override these settings for a given project by following these steps: - </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Select <code class="filename">Project -> Change Yocto Project Settings</code>: - This selection brings up the <code class="filename">Yocot Project Settings</code> Dialog - and allows you to make changes specific to an individual project. - </p><p>By default, the Cross Compiler Options and Target Options for a project - are inherited from settings you provide using the <code class="filename">Preferences</code> - Dialog as described earlier - in the "<a class="link" href="#configuring-the-eclipse-yocto-plug-in" title="5.2.2.1.5. Configuring the Eclipse Yocto Plug-in">Configuring the Eclipse - Yocto Plug-in</a>" section. - The <code class="filename">Yocto Project Settings</code> - Dialog allows you to override those default settings - for a given project.</p></li><li class="listitem"><p>Make your configurations for the project and click "OK".</p></li><li class="listitem"><p>Select <code class="filename">Project -> Reconfigure Project</code>: - This selection reconfigures the project by running - <code class="filename">autogen.sh</code> in the workspace for your project. - The script also runs <code class="filename">libtoolize</code>, <code class="filename">aclocal</code>, - <code class="filename">autoconf</code>, <code class="filename">autoheader</code>, - <code class="filename">automake --a</code>, and - <code class="filename">./configure</code>. - Click on the <code class="filename">Console</code> tab beneath your source code to - see the results of reconfiguring your project.</p></li></ol></div><p> - </p></div><div class="section" title="5.2.2.4. Building the Project"><div class="titlepage"><div><div><h4 class="title"><a id="building-the-project"></a>5.2.2.4. Building the Project</h4></div></div></div><p> - To build the project, select <code class="filename">Project -> Build Project</code>. - The console should update and you can note the cross-compiler you are using. - </p></div><div class="section" title="5.2.2.5. Starting QEMU in User Space NFS Mode"><div class="titlepage"><div><div><h4 class="title"><a id="starting-qemu-in-user-space-nfs-mode"></a>5.2.2.5. Starting QEMU in User Space NFS Mode</h4></div></div></div><p> - To start the QEMU emulator from within Eclipse, follow these steps: - </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Expose the <code class="filename">Run -> External Tools</code> menu. - Your image should appear as a selectable menu item. - </p></li><li class="listitem"><p>Select your image from the menu to launch the - emulator in a new window.</p></li><li class="listitem"><p>If needed, enter your host root password in the shell window at the prompt. - This sets up a <code class="filename">Tap 0</code> connection needed for running in user-space - NFS mode.</p></li><li class="listitem"><p>Wait for QEMU to launch.</p></li><li class="listitem"><p>Once QEMU launches, you can begin operating within that - environment. - For example, you could determine the IP Address - for the user-space NFS by using the <code class="filename">ifconfig</code> command. - </p></li></ol></div><p> - </p></div><div class="section" title="5.2.2.6. Deploying and Debugging the Application"><div class="titlepage"><div><div><h4 class="title"><a id="deploying-and-debugging-the-application"></a>5.2.2.6. Deploying and Debugging the Application</h4></div></div></div><p> - Once the QEMU emulator is running the image, using the Eclipse IDE - you can deploy your application and use the emulator to perform debugging. - Follow these steps to deploy the application. - </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Select <code class="filename">Run -> Debug Configurations...</code></p></li><li class="listitem"><p>In the left area, expand <code class="filename">C/C++Remote Application</code>.</p></li><li class="listitem"><p>Locate your project and select it to bring up a new - tabbed view in the <code class="filename">Debug Configurations</code> Dialog.</p></li><li class="listitem"><p>Enter the absolute path into which you want to deploy - the application. - Use the <code class="filename">Remote Absolute File Path for C/C++Application:</code> field. - For example, enter <code class="filename">/usr/bin/<programname></code>.</p></li><li class="listitem"><p>Click on the <code class="filename">Debugger</code> tab to see the cross-tool debugger - you are using.</p></li><li class="listitem"><p>Click on the <code class="filename">Main</code> tab.</p></li><li class="listitem"><p>Create a new connection to the QEMU instance - by clicking on <code class="filename">new</code>.</p></li><li class="listitem"><p>Select <code class="filename">TCF</code>, which means Target Communication - Framework.</p></li><li class="listitem"><p>Click <code class="filename">Next</code>.</p></li><li class="listitem"><p>Clear out the <code class="filename">host name</code> field and enter the IP Address - determined earlier.</p></li><li class="listitem"><p>Click <code class="filename">Finish</code> to close the - <code class="filename">New Connections</code> Dialog.</p></li><li class="listitem"><p>Use the drop-down menu now in the <code class="filename">Connection</code> field and pick - the IP Address you entered.</p></li><li class="listitem"><p>Click <code class="filename">Debug</code> to bring up a login screen - and login.</p></li><li class="listitem"><p>Accept the debug perspective.</p></li></ol></div><p> - </p></div><div class="section" title="5.2.2.7. Running User-Space Tools"><div class="titlepage"><div><div><h4 class="title"><a id="running-user-space-tools"></a>5.2.2.7. Running User-Space Tools</h4></div></div></div><p> - As mentioned earlier in the manual, several tools exist that enhance - your development experience. - These tools are aids in developing and debugging applications and images. - You can run these user-space tools from within the Eclipse IDE through the - <code class="filename">YoctoTools</code> menu. - </p><p> - Once you pick a tool, you need to configure it for the remote target. - Every tool needs to have the connection configured. - You must select an existing TCF-based RSE connection to the remote target. - If one does not exist, click <code class="filename">New</code> to create one. - </p><p> - Here are some specifics about the remote tools: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><span class="emphasis"><em><code class="filename">OProfile</code>:</em></span> Selecting this tool causes - the <code class="filename">oprofile-server</code> on the remote target to launch on - the local host machine. - The <code class="filename">oprofile-viewer</code> must be installed on the local host machine and the - <code class="filename">oprofile-server</code> must be installed on the remote target, - respectively, in order to use. - You must compile and install the <code class="filename">oprofile-viewer</code> from the source code - on your local host machine. - Furthermore, in order to convert the target's sample format data into a form that the - host can use, you must have <code class="filename">oprofile</code> version 0.9.4 or - greater installed on the host.</p><p>You can locate both the viewer and server from - <a class="ulink" href="http://git.yoctoproject.org/cgit/cgit.cgi/oprofileui/" target="_top">http://git.yoctoproject.org/cgit/cgit.cgi/oprofileui/</a>. - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>The <code class="filename">oprofile-server</code> is installed by default on - the <code class="filename">core-image-sato-sdk</code> image.</div></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">Lttng-ust</code>:</em></span> Selecting this tool runs - <code class="filename">usttrace</code> on the remote target, transfers the output data back - to the local host machine, and uses the <code class="filename">lttng</code> Eclipse plug-in to - graphically display the output. - For information on how to use <code class="filename">lttng</code> to trace an application, see - <a class="ulink" href="http://lttng.org/files/ust/manual/ust.html" target="_top">http://lttng.org/files/ust/manual/ust.html</a>.</p><p>For <code class="filename">Application</code>, you must supply the absolute path name of the - application to be traced by user mode <code class="filename">lttng</code>. - For example, typing <code class="filename">/path/to/foo</code> triggers - <code class="filename">usttrace /path/to/foo</code> on the remote target to trace the - program <code class="filename">/path/to/foo</code>.</p><p><code class="filename">Argument</code> is passed to <code class="filename">usttrace</code> - running on the remote target.</p><p>Before you use the <code class="filename">lttng-ust</code> tool, you need to setup - the <code class="filename">lttng</code> Eclipse plug-in and create a <code class="filename">lttng</code> - project. - Do the following: - </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Follow these - <a class="ulink" href="http://wiki.eclipse.org/Linux_Tools_Project/LTTng#Downloading_and_installing_the_LTTng_parser_library" target="_top">instructions</a> - to download and install the <code class="filename">lttng</code> parser library. - </p></li><li class="listitem"><p>Select <code class="filename">Window -> Open Perspective -> Other</code> - and then select <code class="filename">LTTng</code>.</p></li><li class="listitem"><p>Click <code class="filename">OK</code> to change the Eclipse perspective - into the <code class="filename">LTTng</code> perspective.</p></li><li class="listitem"><p>Create a new <code class="filename">LTTng</code> project by selecting - <code class="filename">File -> New -> Project</code>.</p></li><li class="listitem"><p>Choose <code class="filename">LTTng -> LTTng Project</code>.</p></li><li class="listitem"><p>Click <code class="filename">YoctoTools -> lttng-ust</code> to start user mode - <code class="filename">lttng</code> on the remote target.</p></li></ol></div><p>After the output data has been transferred from the remote target back to the local - host machine, new traces will be imported into the selected <code class="filename">LTTng</code> project. - Then you can go to the <code class="filename">LTTng</code> project, right click the imported - trace, and set the trace type as the <code class="filename">LTTng</code> kernel trace. - Finally, right click the imported trace and select <code class="filename">Open</code> - to display the data graphically.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">PowerTOP</code>:</em></span> Selecting this tool runs - <code class="filename">powertop</code> on the remote target machine and displays the results in a - new view called <code class="filename">powertop</code>.</p><p><code class="filename">Time to gather data(sec):</code> is the time passed in seconds before data - is gathered from the remote target for analysis.</p><p><code class="filename">show pids in wakeups list:</code> corresponds to the - <code class="filename">-p</code> argument - passed to <code class="filename">powertop</code>.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">LatencyTOP and Perf</code>:</em></span> - <code class="filename">latencytop</code> identifies system latency, while - <code class="filename">perf</code> monitors the system's - performance counter registers. - Selecting either of these tools causes an RSE terminal view to appear - from which you can run the tools. - Both tools refresh the entire screen to display results while they run.</p></li></ul></div><p> - </p></div><div class="section" title="5.2.2.8. Customizing an Image Using a BitBake Commander Project and Hob"><div class="titlepage"><div><div><h4 class="title"><a id="customizing-an-image-using-a-bitbake-commander-project-and-hob"></a>5.2.2.8. Customizing an Image Using a BitBake Commander Project and Hob</h4></div></div></div><p> - Within Eclipse, you can create a Yocto BitBake Commander project, - edit the metadata, and then use the - <a class="ulink" href="http://www.yoctoproject.org/projects/hob" target="_top">Hob</a> to build a customized - image all within one IDE. - </p><div class="section" title="5.2.2.8.1. Creating the Yocto BitBake Commander Project"><div class="titlepage"><div><div><h5 class="title"><a id="creating-the-yocto-bitbake-commander-project"></a>5.2.2.8.1. Creating the Yocto BitBake Commander Project</h5></div></div></div><p> - To create a Yocto BitBake Commander project, follow these steps: - </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Select <code class="filename">Window -> Open Perspective -> Other</code> - and then choose <code class="filename">Bitbake Commander</code>.</p></li><li class="listitem"><p>Click <code class="filename">OK</code> to change the Eclipse perspective into the - Bitbake Commander perspective.</p></li><li class="listitem"><p>Select <code class="filename">File -> New -> Project</code> to create a new Yocto - Bitbake Commander project.</p></li><li class="listitem"><p>Choose <code class="filename">Yocto Project Bitbake Commander -> New Yocto Project</code> - and click <code class="filename">Next</code>.</p></li><li class="listitem"><p>Enter the Project Name and choose the Project Location. - The Yocto project's metadata files will be put under the directory - <code class="filename"><project_location>/<project_name></code>. - If that directory does not exist, you need to check - the "Clone from Yocto Git Repository" box, which would execute a - <code class="filename">git clone</code> command to get the project's metadata files. - </p></li><li class="listitem"><p>Select <code class="filename">Finish</code> to create the project.</p></li></ol></div><p> - </p></div><div class="section" title="5.2.2.8.2. Editing the Metadata Files"><div class="titlepage"><div><div><h5 class="title"><a id="editing-the-metadata-files"></a>5.2.2.8.2. Editing the Metadata Files</h5></div></div></div><p> - After you create the Yocto Bitbake Commander project, you can modify the metadata files - by opening them in the project. - When editing recipe files (<code class="filename">.bb</code> files), you can view BitBake - variable values and information by hovering the mouse pointer over the variable name and - waiting a few seconds. - </p><p> - To edit the metadata, follow these steps: - </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Select your Yocto Bitbake Commander project.</p></li><li class="listitem"><p>Select <code class="filename">File -> New -> Yocto BitBake Commander -> BitBake Recipe</code> - to open a new recipe wizard.</p></li><li class="listitem"><p>Point to your source by filling in the "SRC_URL" field. - For example, you can add a recipe to your - <a class="link" href="#source-directory" target="_top">source directory</a> - by defining "SRC_URL" as follows: - </p><pre class="literallayout"> - ftp://ftp.gnu.org/gnu/m4/m4-1.4.9.tar.gz - </pre></li><li class="listitem"><p>Click "Populate" to calculate the archive md5, sha256, - license checksum values and to auto-generate the recipe filename.</p></li><li class="listitem"><p>Fill in the "Description" field.</p></li><li class="listitem"><p>Be sure values for all required fields exist.</p></li><li class="listitem"><p>Click <code class="filename">Finish</code>.</p></li></ol></div><p> - </p></div><div class="section" title="5.2.2.8.3. Building and Customizing the Image"><div class="titlepage"><div><div><h5 class="title"><a id="buiding-and-customizing-the-image"></a>5.2.2.8.3. Building and Customizing the Image</h5></div></div></div><p> - To build and customize the image in Eclipse, follow these steps: - </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Select your Yocto Bitbake Commander project.</p></li><li class="listitem"><p>Select <code class="filename">Project -> Launch HOB</code>.</p></li><li class="listitem"><p>Enter the build directory where you want to put your final images.</p></li><li class="listitem"><p>Click <code class="filename">OK</code> to launch Hob.</p></li><li class="listitem"><p>Use Hob to customize and build your own images. - For information on Hob, see the - <a class="ulink" href="http://www.yoctoproject.org/projects/hob" target="_top">Hob Project Page</a> on the - Yocto Project website.</p></li></ol></div><p> - </p></div></div></div><div class="section" title="5.2.3. Workflow Using Stand-alone Cross-development Toolchains"><div class="titlepage"><div><div><h3 class="title"><a id="workflow-using-stand-alone-cross-development-toolchains"></a>5.2.3. Workflow Using Stand-alone Cross-development Toolchains</h3></div></div></div><p> - If you want to develop an application without prior installation of the ADT, you - still can employ the cross-development toolchain, the QEMU emulator, and a number of supported - target image files. - You just need to follow these general steps: - </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p><span class="emphasis"><em>Install the cross-development toolchain for your target hardware:</em></span> - For information on how to install the toolchain, see the - "<a class="link" href="#using-an-existing-toolchain-tarball" target="_top">Using a Cross-Toolchain Tarball</a>" - section - in the Yocto Project Application Developer's Guide.</p></li><li class="listitem"><p><span class="emphasis"><em>Download the Target Image:</em></span> The Yocto Project supports - several target architectures and has many pre-built kernel images and root filesystem - images.</p><p>If you are going to develop your application on hardware, go to the - <a class="ulink" href="http://downloads.yoctoproject.org/releases/yocto/yocto-1.3/machines" target="_top"><code class="filename">machines</code></a> - download area and choose a target machine area - from which to download the kernel image and root filesystem. - This download area could have several files in it that support development using - actual hardware. - For example, the area might contain <code class="filename">.hddimg</code> files that combine the - kernel image with the filesystem, boot loaders, etc. - Be sure to get the files you need for your particular development process.</p><p>If you are going to develop your application and then run and test it using the QEMU - emulator, go to the - <a class="ulink" href="http://downloads.yoctoproject.org/releases/yocto/yocto-1.3/machines/qemu" target="_top"><code class="filename">machines/qemu</code></a> - download area. - From this area, go down into the directory for your target architecture - (e.g. <code class="filename">qemux86_64</code> for an - <span class="trademark">Intel</span>®-based 64-bit architecture). - Download kernel, root filesystem, and any other files you need for your process. - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>In order to use the root filesystem in QEMU, you need to extract it. - See the - "<a class="link" href="#extracting-the-root-filesystem" target="_top">Extracting the Root Filesystem</a>" - section for information on how to extract the root filesystem.</div></li><li class="listitem"><p><span class="emphasis"><em>Develop and Test your Application:</em></span> At this point, - you have the tools to develop your application. - If you need to separately install and use the QEMU emulator, you can go to - <a class="ulink" href="http://www.qemu.org" target="_top">QEMU Home Page</a> to download and learn about the - emulator.</p></li></ol></div><p> - </p></div></div><div class="section" title="5.3. Modifying Temporary Source Code"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="modifying-temporary-source-code"></a>5.3. Modifying Temporary Source Code</h2></div></div></div><p> - You might - find it helpful during development to modify the temporary source code used by recipes - to build packages. - For example, suppose you are developing a patch and you need to experiment a bit - to figure out your solution. - After you have initially built the package, you can iteratively tweak the - source code, which is located in the - <a class="link" href="#build-directory">build directory</a>, and then - you can force a re-compile and quickly test your altered code. - Once you settle on a solution, you can then preserve your changes in the form of - patches. - You can accomplish these steps all within either a - <a class="ulink" href="http://savannah.nongnu.org/projects/quilt" target="_top">Quilt</a> or - <a class="link" href="#git" title="3.6. Git">Git</a> workflow. - </p><div class="section" title="5.3.1. Finding the Temporary Source Code"><div class="titlepage"><div><div><h3 class="title"><a id="finding-the-temporary-source-code"></a>5.3.1. Finding the Temporary Source Code</h3></div></div></div><p> - During a build, the unpacked temporary source code used by recipes - to build packages is available in the build directory as - defined by the - <code class="filename"><a class="link" href="#var-S" target="_top">S</a></code> variable. - Below is the default value for the <code class="filename">S</code> variable as defined in the - <code class="filename">meta/conf/bitbake.conf</code> configuration file in the - <a class="link" href="#source-directory">source directory</a>: - </p><pre class="literallayout"> - S = ${WORKDIR}/${BP} - </pre><p> - You should be aware that many recipes override the <code class="filename">S</code> variable. - For example, recipes that fetch their source from Git usually set - <code class="filename">S</code> to <code class="filename">${WORKDIR}/git</code>. - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><code class="filename">BP</code> represents the "Base Package", which is the base package - name and the package version: - <pre class="literallayout"> - BP = ${BPN}-${PV} - </pre></div><p> - </p><p> - The path to the work directory for the recipe - (<a class="link" href="#var-WORKDIR" target="_top"><code class="filename">WORKDIR</code></a>) depends - on the package name and the architecture of the target device. - For example, here is the work directory for packages whose targets are not device-dependent: - </p><pre class="literallayout"> - ${TMPDIR}/work/${PACKAGE_ARCH}-poky-${TARGET_OS}/${PN}-${PV}-${PR} - </pre><p> - Let's look at an example without variables. - Assuming a top-level source directory named <code class="filename">poky</code> - and a default build directory of <code class="filename">poky/build</code>, - the following is the work directory for the <code class="filename">acl</code> package: - </p><pre class="literallayout"> - ~/poky/build/tmp/work/i586-poky-linux/acl-2.2.51-r3 - </pre><p> - </p><p> - If your package is dependent on the target device, the work directory varies slightly: - </p><pre class="literallayout"> - ${TMPDIR}/work/${MACHINE}-poky-${TARGET_OS}/${PN}-${PV}-${PR} - </pre><p> - Again, assuming top-level source directory named <code class="filename">poky</code> - and a default build directory of <code class="filename">poky/build</code>, the - following is the work directory for the <code class="filename">acl</code> package that is being - built for a MIPS-based device: - </p><pre class="literallayout"> - ~/poky/build/tmp/work/mips-poky-linux/acl-2.2.51-r2 - </pre><p> - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3> - To better understand how the OpenEmbedded build system resolves directories during the - build process, see the glossary entries for the - <a class="link" href="#var-WORKDIR" target="_top"><code class="filename">WORKDIR</code></a>, - <a class="link" href="#var-TMPDIR" target="_top"><code class="filename">TMPDIR</code></a>, - <a class="link" href="#var-TOPDIR" target="_top"><code class="filename">TOPDIR</code></a>, - <a class="link" href="#var-PACKAGE_ARCH" target="_top"><code class="filename">PACKAGE_ARCH</code></a>, - <a class="link" href="#var-TARGET_OS" target="_top"><code class="filename">TARGET_OS</code></a>, - <a class="link" href="#var-PN" target="_top"><code class="filename">PN</code></a>, - <a class="link" href="#var-PV" target="_top"><code class="filename">PV</code></a>, - and - <a class="link" href="#var-PR" target="_top"><code class="filename">PR</code></a> - variables in the Yocto Project Reference Manual. - </div><p> - Now that you know where to locate the directory that has the temporary source code, you can use a - Quilt or Git workflow to make your edits, test the changes, and preserve the - changes in the form of patches. - </p></div><div class="section" title="5.3.2. Using a Quilt Workflow"><div class="titlepage"><div><div><h3 class="title"><a id="using-a-quilt-workflow"></a>5.3.2. Using a Quilt Workflow</h3></div></div></div><p> - <a class="ulink" href="http://savannah.nongnu.org/projects/quilt" target="_top">Quilt</a> - is a powerful tool that allows you to capture source code changes without having - a clean source tree. - This section outlines the typical workflow you can use to modify temporary source code, - test changes, and then preserve the changes in the form of a patch all using Quilt. - </p><p> - Follow these general steps: - </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p><span class="emphasis"><em>Find the Source Code:</em></span> - The temporary source code used by the OpenEmbedded build system is kept in the - build directory. - See the - "<a class="link" href="#finding-the-temporary-source-code" title="5.3.1. Finding the Temporary Source Code">Finding the Temporary Source Code</a>" - section to learn how to locate the directory that has the temporary source code for a - particular package.</p></li><li class="listitem"><p><span class="emphasis"><em>Change Your Working Directory:</em></span> - You need to be in the directory that has the temporary source code. - That directory is defined by the - <a class="link" href="#var-S" target="_top">S</a> - variable.</p></li><li class="listitem"><p><span class="emphasis"><em>Create a New Patch:</em></span> - Before modifying source code, you need to create a new patch. - To create a new patch file, use <code class="filename">quilt new</code> as below: - </p><pre class="literallayout"> - $ quilt new my_changes.patch - </pre></li><li class="listitem"><p><span class="emphasis"><em>Notify Quilt and Add Files:</em></span> - After creating the patch, you need to notify Quilt about the files you will - be changing. - Add the files you will be modifying into the patch you just created: - </p><pre class="literallayout"> - $ quilt add file1.c file2.c file3.c - </pre></li><li class="listitem"><p><span class="emphasis"><em>Edit the Files:</em></span> - Make the changes to the temporary source code.</p></li><li class="listitem"><p><span class="emphasis"><em>Test Your Changes:</em></span> - Once you have modified the source code, the easiest way to test your changes - is by calling the <code class="filename">compile</code> task as shown in the following example: - </p><pre class="literallayout"> - $ bitbake -c compile -f <name_of_package> - </pre><p> - The <code class="filename">-f</code> or <code class="filename">--force</code> - option forces re-execution of the specified task. - If you find problems with your code, you can just keep editing and - re-testing iteratively until things work as expected. - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>All the modifications you make to the temporary source code - disappear once you <code class="filename">-c clean</code> or - <code class="filename">-c cleanall</code> with BitBake for the package. - Modifications will also disappear if you use the <code class="filename">rm_work</code> - feature as described in the - "<a class="link" href="#building-image" target="_top">Building an Image</a>" - section of the Yocto Project Quick Start. - </div></li><li class="listitem"><p><span class="emphasis"><em>Generate the Patch:</em></span> - Once your changes work as expected, you need to use Quilt to generate the final patch that - contains all your modifications. - </p><pre class="literallayout"> - $ quilt refresh - </pre><p> - At this point the <code class="filename">my_changes.patch</code> file has all your edits made - to the <code class="filename">file1.c</code>, <code class="filename">file2.c</code>, and - <code class="filename">file3.c</code> files.</p><p>You can find the resulting patch file in the <code class="filename">patches/</code> - subdirectory of the source (<code class="filename">S</code>) directory.</p></li><li class="listitem"><p><span class="emphasis"><em>Copy the Patch File:</em></span> - For simplicity, copy the patch file into a directory named <code class="filename">files</code>, - which you can create in the same directory as the recipe. - Placing the patch here guarantees that the OpenEmbedded build system will find - the patch. - Next, add the patch into the - <code class="filename"><a class="link" href="#var-SRC_URI" target="_top">SRC_URI</a></code> - of the recipe. - Here is an example: - </p><pre class="literallayout"> - SRC_URI += "file://my_changes.patch" - </pre></li><li class="listitem"><p><span class="emphasis"><em>Increment the Package Revision Number:</em></span> - Finally, don't forget to 'bump' the - <code class="filename"><a class="link" href="#var-PR" target="_top">PR</a></code> - value in the same recipe since the resulting packages have changed.</p></li></ol></div><p> - </p></div><div class="section" title="5.3.3. Using a Git Workflow"><div class="titlepage"><div><div><h3 class="title"><a id="using-a-git-workflow"></a>5.3.3. Using a Git Workflow</h3></div></div></div><p> - Git is an even more powerful tool that allows you to capture source code changes without having - a clean source tree. - This section outlines the typical workflow you can use to modify temporary source code, - test changes, and then preserve the changes in the form of a patch all using Git. - For general information on Git as it is used in the Yocto Project, see the - "<a class="link" href="#git" title="3.6. Git">Git</a>" section. - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3> - This workflow uses Git only for its ability to manage local changes to the source code - and produce patches independent of any version control system used with the Yocto Project. - </div><p> - Follow these general steps: - </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p><span class="emphasis"><em>Find the Source Code:</em></span> - The temporary source code used by the OpenEmbedded build system is kept in the - build directory. - See the - "<a class="link" href="#finding-the-temporary-source-code" title="5.3.1. Finding the Temporary Source Code">Finding the Temporary Source Code</a>" - section to learn how to locate the directory that has the temporary source code for a - particular package.</p></li><li class="listitem"><p><span class="emphasis"><em>Change Your Working Directory:</em></span> - You need to be in the directory that has the temporary source code. - That directory is defined by the - <a class="link" href="#var-S" target="_top">S</a> - variable.</p></li><li class="listitem"><p><span class="emphasis"><em>Initialize a Git Repository:</em></span> - Use the <code class="filename">git init</code> command to initialize a new local repository - that is based on the work directory: - </p><pre class="literallayout"> - $ git init - </pre></li><li class="listitem"><p><span class="emphasis"><em>Stage all the files:</em></span> - Use the <code class="filename">git add *</code> command to stage all the files in the source - code directory so that they can be committed: - </p><pre class="literallayout"> - $ git add * - </pre></li><li class="listitem"><p><span class="emphasis"><em>Commit the Source Files:</em></span> - Use the <code class="filename">git commit</code> command to initially commit all the files in - the work directory: - </p><pre class="literallayout"> - $ git commit - </pre><p> - At this point, your Git repository is aware of all the source code files. - Any edits you now make to files will be tracked by Git.</p></li><li class="listitem"><p><span class="emphasis"><em>Edit the Files:</em></span> - Make the changes to the temporary source code.</p></li><li class="listitem"><p><span class="emphasis"><em>Test Your Changes:</em></span> - Once you have modified the source code, the easiest way to test your changes - is by calling the <code class="filename">compile</code> task as shown in the following example: - </p><pre class="literallayout"> - $ bitbake -c compile -f <name_of_package> - </pre><p> - The <code class="filename">-f</code> or <code class="filename">--force</code> - option forces re-execution of the specified task. - If you find problems with your code, you can just keep editing and - re-testing iteratively until things work as expected. - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>All the modifications you make to the temporary source code - disappear once you <code class="filename">-c clean</code> or - <code class="filename">-c cleanall</code> with BitBake for the package. - Modifications will also disappear if you use the <code class="filename">rm_work</code> - feature as described in the - "<a class="link" href="#building-image" target="_top">Building an Image</a>" - section of the Yocto Project Quick Start. - </div></li><li class="listitem"><p><span class="emphasis"><em>See the List of Files You Changed:</em></span> - Use the <code class="filename">git status</code> command to see what files you have actually edited. - The ability to have Git track the files you have changed is an advantage that this - workflow has over the Quilt workflow. - Here is the Git command to list your changed files: - </p><pre class="literallayout"> - $ git status - </pre></li><li class="listitem"><p><span class="emphasis"><em>Stage the Modified Files:</em></span> - Use the <code class="filename">git add</code> command to stage the changed files so they - can be committed as follows: - </p><pre class="literallayout"> - $ git add file1.c file2.c file3.c - </pre></li><li class="listitem"><p><span class="emphasis"><em>Commit the Staged Files and View Your Changes:</em></span> - Use the <code class="filename">git commit</code> command to commit the changes to the - local repository. - Once you have committed the files, you can use the <code class="filename">git log</code> - command to see your changes: - </p><pre class="literallayout"> - $ git commit - $ git log - </pre></li><li class="listitem"><p><span class="emphasis"><em>Generate the Patch:</em></span> - Once the changes are committed, use the <code class="filename">git format-patch</code> - command to generate a patch file: - </p><pre class="literallayout"> - $ git format-patch HEAD~1 - </pre><p> - The <code class="filename">HEAD~1</code> part of the command causes Git to generate the - patch file for the most recent commit.</p><p>At this point, the patch file has all your edits made - to the <code class="filename">file1.c</code>, <code class="filename">file2.c</code>, and - <code class="filename">file3.c</code> files. - You can find the resulting patch file in the current directory. - The patch file ends with <code class="filename">.patch</code>.</p></li><li class="listitem"><p><span class="emphasis"><em>Copy the Patch File:</em></span> - For simplicity, copy the patch file into a directory named <code class="filename">files</code>, - which you can create in the same directory as the recipe. - Placing the patch here guarantees that the OpenEmbedded build system will find - the patch. - Next, add the patch into the - <code class="filename"><a class="link" href="#var-SRC_URI" target="_top">SRC_URI</a></code> - of the recipe. - Here is an example: - </p><pre class="literallayout"> - SRC_URI += "file://my_changes.patch" - </pre></li><li class="listitem"><p><span class="emphasis"><em>Increment the Package Revision Number:</em></span> - Finally, don't forget to 'bump' the - <code class="filename"><a class="link" href="#var-PR" target="_top">PR</a></code> - value in the same recipe since the resulting packages have changed.</p></li></ol></div><p> - </p></div></div><div class="section" title="5.4. Image Development Using Hob"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="image-development-using-hob"></a>5.4. Image Development Using Hob</h2></div></div></div><p> - The <a class="ulink" href="http://www.yoctoproject.org/projects/hob" target="_top">Hob</a> is a graphical user interface for the - OpenEmbedded build system, which is based on BitBake. - You can use the Hob to build custom operating system images within the Yocto Project build environment. - Hob simply provides a friendly interface over the build system used during system development. - In other words, building images with the Hob lets you take care of common build tasks more easily. - </p><p> - For a better understanding of Hob, see the project page at - <a class="ulink" href="http://www.yoctoproject.org/projects/hob" target="_top">http://www.yoctoproject.org/projects/hob</a> on the Yocto Project website. - The page has a short introductory training video on Hob. - The following lists some features of Hob: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>You can setup and run Hob using these commands: - </p><pre class="literallayout"> - $ source oe-init-build-env - $ hob - </pre></li><li class="listitem"><p>You can set the - <a class="link" href="#var-MACHINE" target="_top"><code class="filename">MACHINE</code></a> - for which you are building the image.</p></li><li class="listitem"><p>You can modify various policy settings such as the package format used to build with, - the parrallelism BitBake uses, whether or not to build an external toolchain, and which host - to build against.</p></li><li class="listitem"><p>You can manage - <a class="link" href="#understanding-and-creating-layers" title="4.1. Understanding and Creating Layers">layers</a>.</p></li><li class="listitem"><p>You can select a base image and then add extra packages for your custom build. - </p></li><li class="listitem"><p>You can launch and monitor the build from within Hob.</p></li></ul></div><p> - </p></div><div class="section" title="5.5. Using a Development Shell"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="platdev-appdev-devshell"></a>5.5. Using a Development Shell</h2></div></div></div><p> - When debugging certain commands or even when just editing packages, - <code class="filename">devshell</code> can be a useful tool. - When you invoke <code class="filename">devshell</code>, source files are - extracted into your working directory and patches are applied. - Then, a new terminal is opened and you are placed in the working directory. - In the new terminal, all the OpenEmbedded build-related environment variables are - still defined so you can use commands such as <code class="filename">configure</code> and - <code class="filename">make</code>. - The commands execute just as if the OpenEmbedded build system were executing them. - Consequently, working this way can be helpful when debugging a build or preparing - software to be used with the OpenEmbedded build system. - </p><p> - Following is an example that uses <code class="filename">devshell</code> on a target named - <code class="filename">matchbox-desktop</code>: - </p><pre class="literallayout"> - $ bitbake matchbox-desktop -c devshell - </pre><p> - </p><p> - This command opens a terminal with a shell prompt within the OpenEmbedded build environment. - The default shell is xterm. - The following occurs: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>The <code class="filename">PATH</code> variable includes the - cross-toolchain.</p></li><li class="listitem"><p>The <code class="filename">pkgconfig</code> variables find the correct - <code class="filename">.pc</code> files.</p></li><li class="listitem"><p>The <code class="filename">configure</code> command finds the - Yocto Project site files as well as any other necessary files.</p></li></ul></div><p> - Within this environment, you can run <code class="filename">configure</code> - or <code class="filename">compile</code> commands as if they were being run by - the OpenEmbedded build system itself. - As noted earlier, the working directory also automatically changes to the - source directory (<a class="link" href="#var-S" target="_top"><code class="filename">S</code></a>). - </p><p> - When you are finished, you just exit the shell or close the terminal window. - </p><p> - Because an external shell is launched rather than opening directly into the - original terminal window, it allows easier interaction with BitBake's multiple - threads as well as accomodates a future client/server split. - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p> - It is worth remembering that when using <code class="filename">devshell</code> - you need to use the full compiler name such as <code class="filename">arm-poky-linux-gnueabi-gcc</code> - instead of just using <code class="filename">gcc</code>. - The same applies to other applications such as <code class="filename">binutils</code>, - <code class="filename">libtool</code> and so forth. - BitBake sets up environment variables such as <code class="filename">CC</code> - to assist applications, such as <code class="filename">make</code> to find the correct tools. - </p><p> - It is also worth noting that <code class="filename">devshell</code> still works over - X11 forwarding and similar situations - </p></div></div></div> - - <div class="appendix" title="Appendix A. BSP Development Example"><div class="titlepage"><div><div><h2 class="title"><a id="dev-manual-bsp-appendix"></a>Appendix A. BSP Development Example</h2></div></div></div><p> - This appendix provides a complete BSP development example. - The example assumes the following: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>No previous preparation or use of the Yocto Project.</p></li><li class="listitem"><p>Use of the Crown Bay Board Support Package (BSP) as a "base" BSP from - which to work. - The example begins with the Crown Bay BSP as the starting point - but ends by building a new 'atom-pc' BSP, which was based on the Crown Bay BSP. - </p></li><li class="listitem"><p>Shell commands assume <code class="filename">bash</code></p></li><li class="listitem"><p>Example was developed on an Intel-based Core i7 platform running - Ubuntu 10.04 LTS released in April of 2010.</p></li></ul></div><p> -</p><div class="section" title="A.1. Getting Local Source Files and BSP Files"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="getting-local-yocto-project-files-and-bsp-files"></a>A.1. Getting Local Source Files and BSP Files</h2></div></div></div><p> - You need to have the <a class="link" href="#source-directory">source directory</a> - available on your host system. - You can set up this directory through tarball extraction or by cloning the - <code class="filename">poky</code> Git repository. - The following paragraphs describe both methods. - For additional information, see the bulleted item - "<a class="link" href="#local-yp-release">Yocto Project Release</a>". - </p><p> - As mentioned, one way to set up the source directory is to use Git to clone the - <code class="filename">poky</code> repository. - These commands create a local copy of the Git repository. - By default, the top-level directory of the repository is named <code class="filename">poky</code>: - </p><pre class="literallayout"> - $ git clone git://git.yoctoproject.org/poky - $ cd poky - </pre><p> - Alternatively, you can start with the downloaded Poky "1.2+snapshot" tarball. - These commands unpack the tarball into a source directory structure. - By default, the top-level directory of the source directory is named - <code class="filename">poky-1.2+snapshot-8.0</code>: - </p><pre class="literallayout"> - $ tar xfj poky-1.2+snapshot-8.0.tar.bz2 - $ cd poky-1.2+snapshot-8.0 - </pre><p> - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>If you're using the tarball method, you can ignore all the following steps that - ask you to carry out Git operations. - You already have the results of those operations - in the form of the 1.2+snapshot release tarballs. - Consequently, there is nothing left to do other than extract those tarballs into the - proper locations.</p><p>Once you expand the released tarball, you have a snapshot of the Git repository - that represents a specific release. - Fundamentally, this is different than having a local copy of the Poky Git repository. - Given the tarball method, changes you make are building on top of a release. - With the Git repository method you have the ability to track development - and keep changes in revision control. - See the - "<a class="link" href="#repositories-tags-and-branches" title="3.6.1. Repositories, Tags, and Branches">Repositories, Tags, and Branches</a>" section - for more discussion around these differences.</p></div><p> - </p><p> - With the local <code class="filename">poky</code> Git repository set up, - you have all the development branches available to you from which you can work. - Next, you need to be sure that your local repository reflects the exact - release in which you are interested. - From inside the repository you can see the development branches that represent - areas of development that have diverged from the main (master) branch - at some point, such as a branch to track a maintenance release's development. - You can also see the tag names used to mark snapshots of stable releases or - points in the repository. - Use the following commands to list out the branches and the tags in the repository, - respectively. - </p><pre class="literallayout"> - $ git branch -a - $ git tag -l - </pre><p> - For this example, we are going to use the Yocto Project 1.3 Release, which is code - named "1.2+snapshot". - To make sure we have a local area (branch in Git terms) on our machine that - reflects the 1.3 release, we can use the following commands: - </p><pre class="literallayout"> - $ cd ~/poky - $ git fetch --tags - $ git checkout 1.2+snapshot-8.0 -b 1.2+snapshot - Switched to a new branch '1.2+snapshot' - </pre><p> - The <code class="filename">git fetch --tags</code> is somewhat redundant since you just set - up the repository and should have all the tags. - The <code class="filename">fetch</code> command makes sure all the tags are available in your - local repository. - The Git <code class="filename">checkout</code> command with the <code class="filename">-b</code> option - creates a local branch for you named <code class="filename">1.2+snapshot</code>. - Your local branch begins in the same state as the Yocto Project 1.3 released tarball - marked with the <code class="filename">1.2+snapshot-8.0</code> tag in the source repositories. - </p></div><div class="section" title="A.2. Choosing a Base BSP"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="choosing-a-base-bsp-app"></a>A.2. Choosing a Base BSP</h2></div></div></div><p> - For this example, the base BSP is the <span class="trademark">Intel</span>® - <span class="trademark">Atom</span>™ Processor E660 with Intel Platform - Controller Hub EG20T Development Kit, which is otherwise referred to as "Crown Bay." - The BSP layer is <code class="filename">meta-crownbay</code>. - The base BSP is simply the BSP - we will be using as a starting point, so don't worry if you don't actually have Crown Bay - hardware. - The remainder of the example transforms the base BSP into a BSP that should be - able to boot on generic atom-pc (netbook) hardware. - </p><p> - For information on how to choose a base BSP, see - "<a class="link" href="#developing-a-board-support-package-bsp" title="5.1.1. Developing a Board Support Package (BSP)">Developing a Board Support Package (BSP)</a>". - </p></div><div class="section" title="A.3. Getting Your Base BSP"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="getting-your-base-bsp-app"></a>A.3. Getting Your Base BSP</h2></div></div></div><p> - You need to have the base BSP layer on your development system. - Similar to the local <a class="link" href="#source-directory">source directory</a>, - you can get the BSP - layer in a couple of different ways: - download the BSP tarball and extract it, or set up a local Git repository that - has the BSP layers. - You should use the same method that you used to set up the source directory earlier. - See "<a class="link" href="#getting-setup" title="2.2. Getting Set Up">Getting Setup</a>" for information on how to get - the BSP files. - </p><p> - This example assumes the BSP layer will be located within a directory named - <code class="filename">meta-intel</code> contained within the <code class="filename">poky</code> - parent directory. - The following steps will automatically create the - <code class="filename">meta-intel</code> directory and the contained - <code class="filename">meta-crownbay</code> starting point in both the Git and the tarball cases. - </p><p> - If you're using the Git method, you could do the following to create - the starting layout after you have made sure you are in the <code class="filename">poky</code> - directory created in the previous steps: - </p><pre class="literallayout"> - $ git clone git://git.yoctoproject.org/meta-intel.git - $ cd meta-intel - </pre><p> - Alternatively, you can start with the downloaded Crown Bay tarball. - You can download the 1.2+snapshot version of the BSP tarball from the - <a class="ulink" href="http://www.yoctoproject.org/download" target="_top">Download</a> page of the - Yocto Project website. - Here is the specific link for the tarball needed for this example: - <a class="ulink" href="http://downloads.yoctoproject.org/releases/yocto/yocto-1.3/machines/crownbay-noemgd/crownbay-noemgd-1.2+snapshot-8.0.tar.bz2" target="_top">http://downloads.yoctoproject.org/releases/yocto/yocto-1.3/machines/crownbay-noemgd/crownbay-noemgd-1.2+snapshot-8.0.tar.bz2</a>. - Again, be sure that you are already in the <code class="filename">poky</code> directory - as described previously before installing the tarball: - </p><pre class="literallayout"> - $ tar xfj crownbay-noemgd-1.2+snapshot-8.0.tar.bz2 - $ cd meta-intel - </pre><p> - </p><p> - The <code class="filename">meta-intel</code> directory contains all the metadata - that supports BSP creation. - If you're using the Git method, the following - step will switch to the 1.2+snapshot metadata. - If you're using the tarball method, you already have the correct metadata and can - skip to the next step. - Because <code class="filename">meta-intel</code> is its own Git repository, you will want - to be sure you are in the appropriate branch for your work. - For this example we are going to use the <code class="filename">1.2+snapshot</code> branch. - </p><pre class="literallayout"> - $ git checkout -b 1.2+snapshot origin/1.2+snapshot - Branch 1.2+snapshot set up to track remote branch 1.2+snapshot from origin. - Switched to a new branch '1.2+snapshot' - </pre><p> - </p></div><div class="section" title="A.4. Making a Copy of the Base BSP to Create Your New BSP Layer"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="making-a-copy-of-the-base bsp-to-create-your-new-bsp-layer-app"></a>A.4. Making a Copy of the Base BSP to Create Your New BSP Layer</h2></div></div></div><p> - Now that you have set up the source directory and included the base BSP files, you need to - create a new layer for your BSP. - To create your BSP layer, you simply copy the <code class="filename">meta-crownbay</code> - layer to a new layer. - </p><p> - For this example, the new layer will be named <code class="filename">meta-mymachine</code>. - The name should follow the BSP layer naming convention, which is - <code class="filename">meta-<name></code>. - The following assumes your working directory is <code class="filename">meta-intel</code> - inside your source directory. - To start your new layer, just copy the new layer alongside the existing - BSP layers in the <code class="filename">meta-intel</code> directory: - </p><pre class="literallayout"> - $ cp -a meta-crownbay/ meta-mymachine - </pre><p> - </p></div><div class="section" title="A.5. Making Changes to Your BSP"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="making-changes-to-your-bsp-app"></a>A.5. Making Changes to Your BSP</h2></div></div></div><p> - Right now you have two identical BSP layers with different names: - <code class="filename">meta-crownbay</code> and <code class="filename">meta-mymachine</code>. - You need to change your configurations so that they work for your new BSP and - your particular hardware. - The following sections look at each of these areas of the BSP. - </p><div class="section" title="A.5.1. Changing the BSP Configuration"><div class="titlepage"><div><div><h3 class="title"><a id="changing-the-bsp-configuration"></a>A.5.1. Changing the BSP Configuration</h3></div></div></div><p> - We will look first at the configurations, which are all done in the layer’s - <code class="filename">conf</code> directory. - </p><p> - First, since in this example the new BSP will not support EMGD, we will get rid of the - <code class="filename">crownbay.conf</code> file and then rename the - <code class="filename">crownbay-noemgd.conf</code> file to <code class="filename">mymachine.conf</code>. - Much of what we do in the configuration directory is designed to help the OpenEmbedded - build system work with the new layer and to be able to find and use the right software. - The following two commands result in a single machine configuration file named - <code class="filename">mymachine.conf</code>. - </p><pre class="literallayout"> - $ rm meta-mymachine/conf/machine/crownbay.conf - $ mv meta-mymachine/conf/machine/crownbay-noemgd.conf \ - meta-mymachine/conf/machine/mymachine.conf - </pre><p> - </p><p> - Next, we need to make changes to the <code class="filename">mymachine.conf</code> itself. - The only changes we want to make for this example are to the comment lines. - Changing comments, of course, is never strictly necessary, but it's alway good form to make - them reflect reality as much as possible. - - Here, simply substitute the Crown Bay name with an appropriate name for the BSP - (<code class="filename">mymachine</code> in this case) and change the description to - something that describes your hardware. - </p><p> - Note that inside the <code class="filename">mymachine.conf</code> is the - <code class="filename">PREFERRED_VERSION_linux-yocto</code> statement. - This statement identifies the kernel that the BSP is going to use. - In this case, the BSP is using <code class="filename">linux-yocto</code>, which is the - current Yocto Project kernel based on the Linux 3.2 release. - </p><p> - The next configuration file in the new BSP layer we need to edit is - <code class="filename">meta-mymachine/conf/layer.conf</code>. - This file identifies build information needed for the new layer. - You can see the - "<a class="link" href="#bsp-filelayout-layer" target="_top">Layer Configuration File</a>" section - in The Board Support Packages (BSP) Development Guide for more information on this configuration file. - Basically, we are changing the existing statements to work with our BSP. - </p><p> - The file contains these statements that reference the Crown Bay BSP: - </p><pre class="literallayout"> - BBFILE_COLLECTIONS += "crownbay" - BBFILE_PATTERN_crownbay := "^${LAYERDIR}/" - BBFILE_PRIORITY_crownbay = "6" - - LAYERDEPENDS_crownbay = "intel" - </pre><p> - </p><p> - Simply substitute the machine string name <code class="filename">crownbay</code> - with the new machine name <code class="filename">mymachine</code> to get the following: - </p><pre class="literallayout"> - BBFILE_COLLECTIONS += "mymachine" - BBFILE_PATTERN_mymachine := "^${LAYERDIR}/" - BBFILE_PRIORITY_mymachine = "6" - - LAYERDEPENDS_mymachine = "intel" - </pre><p> - </p></div><div class="section" title="A.5.2. Changing the Recipes in Your BSP"><div class="titlepage"><div><div><h3 class="title"><a id="changing-the-recipes-in-your-bsp"></a>A.5.2. Changing the Recipes in Your BSP</h3></div></div></div><p> - Now we will take a look at the recipes in your new layer. - The standard BSP structure has areas for BSP, graphics, core, and kernel recipes. - When you create a BSP, you use these areas for appropriate recipes and append files. - Recipes take the form of <code class="filename">.bb</code> files, while append files take - the form of <code class="filename">.bbappend</code> files. - If you want to leverage the existing recipes the OpenEmbedded build system uses - but change those recipes, you can use <code class="filename">.bbappend</code> files. - All new recipes and append files for your layer must go in the layer’s - <code class="filename">recipes-bsp</code>, <code class="filename">recipes-kernel</code>, - <code class="filename">recipes-core</code>, and - <code class="filename">recipes-graphics</code> directories. - </p><div class="section" title="A.5.2.1. Changing recipes-bsp"><div class="titlepage"><div><div><h4 class="title"><a id="changing-recipes-bsp"></a>A.5.2.1. Changing <code class="filename">recipes-bsp</code></h4></div></div></div><p> - First, let's look at <code class="filename">recipes-bsp</code>. - For this example we are not adding any new BSP recipes. - And, we only need to remove the formfactor we do not want and change the name of - the remaining one that doesn't support EMGD. - These commands take care of the <code class="filename">recipes-bsp</code> recipes: - </p><pre class="literallayout"> - $ rm -rf meta-mymachine/recipes-bsp/formfactor/formfactor/crownbay - $ mv meta-mymachine/recipes-bsp/formfactor/formfactor/crownbay-noemgd/ \ - meta-mymachine/recipes-bsp/formfactor/formfactor/mymachine - </pre><p> - </p></div><div class="section" title="A.5.2.2. Changing recipes-graphics"><div class="titlepage"><div><div><h4 class="title"><a id="changing-recipes-graphics"></a>A.5.2.2. Changing <code class="filename">recipes-graphics</code></h4></div></div></div><p> - Now let's look at <code class="filename">recipes-graphics</code>. - For this example we want to remove anything that supports EMGD and - be sure to rename remaining directories appropriately. - The following commands clean up the <code class="filename">recipes-graphics</code> directory: - </p><pre class="literallayout"> - $ rm -rf meta-mymachine/recipes-graphics/xorg-xserver/xserver-xf86-config/crownbay - $ mv meta-mymachine/recipes-graphics/xorg-xserver/xserver-xf86-config/crownbay-noemgd \ - meta-mymachine/recipes-graphics/xorg-xserver/xserver-xf86-config/mymachine - </pre><p> - </p><p> - At this point the <code class="filename">recipes-graphics</code> directory just has files that - support Video Electronics Standards Association (VESA) graphics modes and not EMGD. - </p></div><div class="section" title="A.5.2.3. Changing recipes-core"><div class="titlepage"><div><div><h4 class="title"><a id="changing-recipes-core"></a>A.5.2.3. Changing <code class="filename">recipes-core</code></h4></div></div></div><p> - Now let's look at changes in <code class="filename">recipes-core</code>. - The file <code class="filename">task-core-tools.bbappend</code> in - <code class="filename">recipes-core/tasks</code> appends the similarly named recipe - located in the <a class="link" href="#source-directory">source directory</a> at - <code class="filename">meta/recipes-core/tasks</code>. - The append file in our layer right now is Crown Bay-specific and supports - EMGD and non-EMGD. - Here are the contents of the file: - </p><pre class="literallayout"> - RRECOMMENDS_task-core-tools-profile_append_crownbay = " systemtap" - RRECOMMENDS_task-core-tools-profile_append_crownbay-noemgd = " systemtap" - </pre><p> - </p><p> - The <code class="filename">RRECOMMENDS</code> statements list packages that - extend usability. - The first <code class="filename">RRECOMMENDS</code> statement can be removed, while the - second one can be changed to reflect <code class="filename">meta-mymachine</code>: - </p><pre class="literallayout"> - RRECOMMENDS_task-core-tools-profile_append_mymachine = " systemtap" - </pre><p> - </p></div><div class="section" title="A.5.2.4. Changing recipes-kernel"><div class="titlepage"><div><div><h4 class="title"><a id="changing-recipes-kernel"></a>A.5.2.4. Changing <code class="filename">recipes-kernel</code></h4></div></div></div><p> - Finally, let's look at <code class="filename">recipes-kernel</code> changes. - Recall that the BSP uses the <code class="filename">linux-yocto</code> kernel as determined - earlier in the <code class="filename">mymachine.conf</code>. - The recipe for that kernel is not located in the - BSP layer but rather in the source directory at - <code class="filename">meta/recipes-kernel/linux</code> and is - named <code class="filename">linux-yocto_3.2.bb</code>. - The <code class="filename">SRCREV_machine</code> and <code class="filename">SRCREV_meta</code> - statements point to the exact commits used by the Yocto Project development team - in their source repositories that identify the right kernel for our hardware. - In other words, the <code class="filename">SRCREV</code> values are simply Git commit - IDs that identify which commit on each - of the kernel branches (machine and meta) will be checked out and used to build - the kernel. - </p><p> - However, in the <code class="filename">meta-mymachine</code> layer in - <code class="filename">recipes-kernel/linux</code> resides a <code class="filename">.bbappend</code> - file named <code class="filename">linux-yocto_3.2.bbappend</code> that - appends information to the recipe of the same name in <code class="filename">meta/recipes-kernel/linux</code>. - Thus, the <code class="filename">SRCREV</code> statements in the append file override - the more general statements found in <code class="filename">meta</code>. - </p><p> - The <code class="filename">SRCREV</code> statements in the append file currently identify - the kernel that supports the Crown Bay BSP with and without EMGD support. - Here are the statements: - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>The commit ID strings used in this manual might not match the actual commit - ID strings found in the <code class="filename">linux-yocto_3.2.bbappend</code> file. - For the example, this difference does not matter.</div><p> - </p><pre class="literallayout"> - SRCREV_machine_pn-linux-yocto_crownbay ?= \ - "211fc7f4d10ec2b82b424286aabbaff9254b7cbd" - SRCREV_meta_pn-linux-yocto_crownbay ?= \ - "514847185c78c07f52e02750fbe0a03ca3a31d8f" - - SRCREV_machine_pn-linux-yocto_crownbay-noemgd ?= \ - "211fc7f4d10ec2b82b424286aabbaff9254b7cbd" - SRCREV_meta_pn-linux-yocto_crownbay-noemgd ?= \ - "514847185c78c07f52e02750fbe0a03ca3a31d8f" - </pre><p> - </p><p> - You will notice that there are two pairs of <code class="filename">SRCREV</code> statements. - The top pair identifies the kernel that supports - EMGD, which we don’t care about in this example. - The bottom pair identifies the kernel that we will use: - <code class="filename">linux-yocto</code>. - At this point though, the unique commit strings all are still associated with - Crown Bay and not <code class="filename">meta-mymachine</code>. - </p><p> - To fix this situation in <code class="filename">linux-yocto_3.2.bbappend</code>, - we delete the two <code class="filename">SRCREV</code> statements that support - EMGD (the top pair). - We also change the remaining pair to specify <code class="filename">mymachine</code> - and insert the commit identifiers to identify the kernel in which we - are interested, which will be based on the <code class="filename">atom-pc-standard</code> - kernel. - In this case, because we're working with the 1.2+snapshot branch of everything, we - need to use the <code class="filename">SRCREV</code> values for the atom-pc branch - that are associated with the 1.2+snapshot release. - To find those values, we need to find the <code class="filename">SRCREV</code> - values that 1.2+snapshot uses for the atom-pc branch, which we find in the - <code class="filename">poky/meta-yocto/recipes-kernel/linux/linux-yocto_3.2.bbappend</code> - file. - </p><p> - The machine <code class="filename">SRCREV</code> we want is in the - <code class="filename">SRCREV_machine_atom-pc</code> variable. - The meta <code class="filename">SRCREV</code> isn't specified in this file, so it must be - specified in the base kernel recipe in the - <code class="filename">poky/meta/recipes-kernel/linux/linux-yocto_3.2.bb</code> - file, in the <code class="filename">SRCREV_meta</code> variable found there. - Here are the final <code class="filename">SRCREV</code> statements: - </p><pre class="literallayout"> - SRCREV_machine_pn-linux-yocto_mymachine ?= \ - "f29531a41df15d74be5ad47d958e4117ca9e489e" - SRCREV_meta_pn-linux-yocto_mymachine ?= \ - "b14a08f5c7b469a5077c10942f4e1aec171faa9d" - </pre><p> - </p><p> - In this example, we're using the <code class="filename">SRCREV</code> values we - found already captured in the 1.2+snapshot release because we're creating a BSP based on - 1.2+snapshot. - If, instead, we had based our BSP on the master branches, we would want to use - the most recent <code class="filename">SRCREV</code> values taken directly from the kernel repo. - We will not be doing that for this example. - However, if you do base a future BSP on master and - if you are familiar with Git repositories, you probably won’t have trouble locating the - exact commit strings in the Yocto Project source repositories you need to change - the <code class="filename">SRCREV</code> statements. - You can find all the <code class="filename">machine</code> and <code class="filename">meta</code> - branch points (commits) for the <code class="filename">linux-yocto-3.2</code> kernel at - <a class="ulink" href="http://git.yoctoproject.org/cgit/cgit.cgi/linux-yocto-3.2" target="_top">http://git.yoctoproject.org/cgit/cgit.cgi/linux-yocto-3.2</a>. - </p><p> - If you need a little more assistance after going to the link then do the following: - </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Expand the list of branches by clicking <code class="filename">[…]</code></p></li><li class="listitem"><p>Click on the <code class="filename">standard/default/common-pc/atom-pc</code> - branch</p></li><li class="listitem"><p>Click on the commit column header to view the top commit</p></li><li class="listitem"><p>Copy the commit string for use in the - <code class="filename">linux-yocto_3.2.bbappend</code> file</p></li></ol></div><p> - </p><p> - For the <code class="filename">SRCREV</code> statement that points to the <code class="filename">meta</code> - branch use the same procedure except expand the <code class="filename">meta</code> - branch in step 2 above. - </p><p> - Also in the <code class="filename">linux-yocto_3.2.bbappend</code> file are - <a class="link" href="#var-COMPATIBLE_MACHINE" target="_top"><code class="filename">COMPATIBLE_MACHINE</code></a>, - <a class="link" href="#var-KMACHINE" target="_top"><code class="filename">KMACHINE</code></a>, - and - <a class="link" href="#var-KBRANCH" target="_top"><code class="filename">KBRANCH</code></a> statements. - Two sets of these exist: one set supports EMGD and one set does not. - Because we are not interested in supporting EMGD those three can be deleted. - The remaining three must be changed so that <code class="filename">mymachine</code> replaces - <code class="filename">crownbay-noemgd</code> and <code class="filename">crownbay</code>. - Because we are using the <code class="filename">atom-pc</code> branch for this new BSP, we can also find - the exact branch we need for the <code class="filename">KMACHINE</code> - and <code class="filename">KBRANCH</code> variables in our new BSP from the value - we find in the - <code class="filename">poky/meta-yocto/recipes-kernel/linux/linux-yocto_3.2.bbappend</code> - file we looked at in a previous step. - In this case, the values we want are in the <code class="filename">KMACHINE_atom-pc</code> variable - and the <code class="filename">KBRANCH_atom-pc</code> variables in that file. - Here is the final <code class="filename">linux-yocto_3.2.bbappend</code> file after all - the edits: - </p><pre class="literallayout"> - FILESEXTRAPATHS_prepend := "${THISDIR}/${PN}:" - - COMPATIBLE_MACHINE_mymachine = "mymachine" - KMACHINE_mymachine = "atom-pc" - KBRANCH_mymachine = "standard/default/common-pc/atom-pc" - - SRCREV_machine_pn-linux-yocto_mymachine ?= \ - "f29531a41df15d74be5ad47d958e4117ca9e489e" - SRCREV_meta_pn-linux-yocto_mymachine ?= \ - "b14a08f5c7b469a5077c10942f4e1aec171faa9d" - </pre><p> - </p></div></div><div class="section" title="A.5.3. BSP Recipe Change Summary"><div class="titlepage"><div><div><h3 class="title"><a id="bsp-recipe-change-summary"></a>A.5.3. BSP Recipe Change Summary</h3></div></div></div><p> - In summary, the edits to the layer’s recipe files result in removal of any files and - statements that do not support your targeted hardware in addition to the inclusion - of any new recipes you might need. - In this example, it was simply a matter of ridding the new layer - <code class="filename">meta-mymachine</code> of any code that supported the EMGD features - and making sure we were identifying the kernel that supports our example, which - is the <code class="filename">atom-pc-standard</code> kernel. - We did not introduce any new recipes to the layer. - </p><p> - Finally, it is also important to update the layer’s <code class="filename">README</code> - file so that the information in it reflects your BSP. - </p></div></div><div class="section" title="A.6. Preparing for the Build"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="preparing-for-the-build-app"></a>A.6. Preparing for the Build</h2></div></div></div><p> - To get ready to build your image that uses the new layer you need to do the following: - </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Get the environment ready for the build by sourcing the environment - script. - The environment script is in the top-level of the source directory. - The script has the string - <code class="filename">init-build-env</code> in the file’s name. - For this example, the following command gets the build environment ready: - </p><pre class="literallayout"> - $ source oe-init-build-env yocto-build - </pre><p> - When you source the script, a build directory is created in the current - working directory. - In our example we were in the <code class="filename">poky</code> directory. - Thus, entering the previous command created the <code class="filename">yocto-build</code> directory. - If you do not provide a name for the build directory it defaults to - <code class="filename">build</code>. - The <code class="filename">yocto-build</code> directory contains a - <code class="filename">conf</code> directory that has - two configuration files you will need to check: <code class="filename">bblayers.conf</code> - and <code class="filename">local.conf</code>.</p></li><li class="listitem"><p>Check and edit the resulting <code class="filename">local.conf</code> file. - This file minimally identifies the machine for which to build the image by - configuring the <code class="filename">MACHINE</code> variable. - For this example you must set the variable to mymachine as follows: - </p><pre class="literallayout"> - MACHINE ??= “mymachine” - </pre><p> - You should also be sure any other variables in which you are interested are set. - Some variables to consider are <code class="filename">BB_NUMBER_THREADS</code> - and <code class="filename">PARALLEL_MAKE</code>, both of which can greatly reduce your build time - if your development system supports multiple cores. - For development systems that support multiple cores, a good rule of thumb is to set - both the <code class="filename">BB_NUMBER_THREADS</code> and <code class="filename">PARALLEL_MAKE</code> - variables to twice the number of cores your system supports.</p></li><li class="listitem"><p>Update the <code class="filename">bblayers.conf</code> file so that it includes - both the path to your new BSP layer and the path to the - <code class="filename">meta-intel</code> layer. - In this example, you need to include both these paths as part of the - <code class="filename">BBLAYERS</code> variable: - </p><pre class="literallayout"> - $HOME/poky/meta-intel - $HOME/poky/meta-intel/meta-mymachine - </pre></li></ol></div><p> - </p><p> - The - <a class="link" href="#ref-variables-glos" target="_top">Variables Glossary</a> chapter in the - Yocto Project Reference Manual has more information on configuration variables. - </p></div><div class="section" title="A.7. Building and Booting the Image"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="building-the-image-app"></a>A.7. Building and Booting the Image</h2></div></div></div><p> - To build the image for our <code class="filename">meta-mymachine</code> BSP enter the following command - from the same shell from which you ran the setup script. - You should run the <code class="filename">bitbake</code> command without any intervening shell commands. - For example, moving your working directory around could cause problems. - Here is the command for this example: - </p><pre class="literallayout"> - $ bitbake -k core-image-sato - </pre><p> - </p><p> - This command specifies an image that has Sato support and that can be run from a USB device or - from a CD without having to first install anything. - The build process takes significant time and includes thousands of tasks, which are reported - at the console. - If the build results in any type of error you should check for misspellings in the - files you changed or problems with your host development environment such as missing packages. - </p><p> - Finally, once you have an image, you can try booting it from a device - (e.g. a USB device). - To prepare a bootable USB device, insert a USB flash drive into your build system and - copy the <code class="filename">.hddimg</code> file, located in the - <code class="filename">poky/build/tmp/deploy/images</code> - directory after a successful build to the flash drive. - Assuming the USB flash drive takes device <code class="filename">/dev/sdf</code>, - use <code class="filename">dd</code> to copy the live image to it. - For example: - </p><pre class="literallayout"> - # dd if=core-image-sato-mymachine-20111101223904.hddimg of=/dev/sdf - # sync - # eject /dev/sdf - </pre><p> - You should now have a bootable USB flash device. - </p><p> - Insert the device - into a bootable USB socket on the target, and power it on. - The system should boot to the Sato graphical desktop. - <sup>[<a id="id1497755" href="#ftn.id1497755" class="footnote">2</a>]</sup> - </p><p> - For reference, the sato image produced by the previous steps for 1.2+snapshot - should look like the following in terms of size. - If your sato image is much different from this, - you probably made a mistake in one of the above steps: - </p><pre class="literallayout"> - 260538368 2012-04-27 01:44 core-image-sato-mymachine-20120427025051.hddimg - </pre><p> - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>The previous instructions are also present in the README that was copied - from meta-crownbay, which should also be updated to reflect the specifics of your - new BSP. - That file and the <code class="filename">README.hardware</code> file in the top-level - <code class="filename">poky</code> directory - also provides some suggestions for things to try if booting fails and produces - strange error messages.</div><p> - </p></div><div class="footnotes"><br /><hr width="100" align="left" /><div class="footnote"><p><sup>[<a id="ftn.id1497755" href="#id1497755" class="para">2</a>] </sup>Because - this new image is not in any way tailored to the system you're - booting it on, which is assumed to be some sort of atom-pc (netbook) system for this - example, it might not be completely functional though it should at least boot to a text - prompt. - Specifically, it might fail to boot into graphics without some tweaking. - If this ends up being the case, a possible next step would be to replace the - <code class="filename">mymachine.conf</code> - contents with the contents of <code class="filename">atom-pc.conf</code> and replace - <code class="filename">xorg.conf</code> with <code class="filename">atom-pc xorg.conf</code> - in <code class="filename">meta-yocto</code> and see if it fares any better. - In any case, following the previous steps will give you a buildable image that - will probably boot on most systems. - Getting things working like you want - them to for your hardware will normally require some amount of experimentation with - configuration settings.</p></div></div></div> - - <div class="appendix" title="Appendix B. Kernel Modification Example"><div class="titlepage"><div><div><h2 class="title"><a id="dev-manual-kernel-appendix"></a>Appendix B. Kernel Modification Example</h2></div></div></div><p> - Kernel modification involves changing or adding configurations to an existing kernel, - changing or adding recipes to the kernel that are needed to support specific hardware features, - or even altering the source code itself. - This appendix presents simple examples that modify the kernel source code, - change the kernel configuration, and add a kernel source recipe. - </p><div class="section" title="B.1. Modifying the Kernel Source Code"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="modifying-the-kernel-source-code"></a>B.1. Modifying the Kernel Source Code</h2></div></div></div><p> - This example adds some simple QEMU emulator console output at boot time by - adding <code class="filename">printk</code> statements to the kernel's - <code class="filename">calibrate.c</code> source code file. - Booting the modified image causes the added messages to appear on the emulator's - console. - </p><div class="section" title="B.1.1. Understanding the Files You Need"><div class="titlepage"><div><div><h3 class="title"><a id="understanding-the-files-you-need"></a>B.1.1. Understanding the Files You Need</h3></div></div></div><p> - Before you modify the kernel, you need to know what Git repositories and file - structures you need. - Briefly, you need the following: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>A local - <a class="link" href="#source-directory">source directory</a> for the - poky Git repository</p></li><li class="listitem"><p>Local copies of the - <a class="link" href="#poky-extras-repo"><code class="filename">poky-extras</code></a> - Git repository placed within the source directory.</p></li><li class="listitem"><p>A bare clone of the - <a class="link" href="#local-kernel-files">Yocto Project Kernel</a> upstream Git - repository to which you want to push your modifications. - </p></li><li class="listitem"><p>A copy of that bare clone in which you make your source - modifications</p></li></ul></div><p> - </p><p> - The following figure summarizes these four areas. - Within each rectangular that represents a data structure, a - host development directory pathname appears at the - lower left-hand corner of the box. - These pathnames are the locations used in this example. - The figure also provides key statements and commands used during the kernel - modification process: - </p><p> - </p><table border="0" summary="manufactured viewport for HTML img" cellspacing="0" cellpadding="0" width="630"><tr style="height: 450px"><td align="center"><img src="figures/kernel-example-repos-denzil.png" align="middle" /></td></tr></table><p> - </p><p> - Here is a brief description of the four areas: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><span class="emphasis"><em>Local Source Directory:</em></span> - This area contains all the metadata that supports building images - using the OpenEmbedded build system. - In this example, the source directory also - contains the build directory, which contains the configuration directory - that lets you control the build. - Also in this example, the source directory contains local copies of the - <code class="filename">poky-extras</code> Git repository.</p><p>See the bulleted item - "<a class="link" href="#local-yp-release">Yocto Project Release</a>" - for information on how to get these files on your local system.</p></li><li class="listitem"><p><span class="emphasis"><em>Local copies of the<code class="filename">poky-extras</code> - Git Repository:</em></span> - This area contains the <code class="filename">meta-kernel-dev</code> layer, - which is where you make changes that append the kernel build recipes. - You edit <code class="filename">.bbappend</code> files to locate your - local kernel source files and to identify the kernel being built. - This Git repository is a gathering place for extensions to the Yocto Project - (or really any) kernel recipes that faciliate the creation and development - of kernel features, BSPs or configurations.</p><p>See the bulleted item - "<a class="link" href="#poky-extras-repo">The - <code class="filename">poky-extras</code> Git Repository</a>" - for information on how to get these files.</p></li><li class="listitem"><p><span class="emphasis"><em>Bare Clone of the Yocto Project kernel:</em></span> - This bare Git repository tracks the upstream Git repository of the Linux - Yocto kernel source code you are changing. - When you modify the kernel you must work through a bare clone. - All source code changes you make to the kernel must be committed and - pushed to the bare clone using Git commands. - As mentioned, the <code class="filename">.bbappend</code> file in the - <code class="filename">poky-extras</code> repository points to the bare clone - so that the build process can locate the locally changed source files.</p><p>See the bulleted item - "<a class="link" href="#local-kernel-files">Yocto Project Kernel</a>" - for information on how to set up the bare clone. - </p></li><li class="listitem"><p><span class="emphasis"><em>Copy of the Yocto Project Kernel Bare Clone:</em></span> - This Git repository contains the actual source files that you modify. - Any changes you make to files in this location need to ultimately be pushed - to the bare clone using the <code class="filename">git push</code> command.</p><p>See the bulleted item - "<a class="link" href="#local-kernel-files">Yocto Project Kernel</a>" - for information on how to set up the bare clone. - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>Typically, Git workflows follow a scheme where changes made to a local area - are pulled into a Git repository. - However, because the <code class="filename">git pull</code> command does not work - with bare clones, this workflow pushes changes to the - repository even though you could use other more complicated methods to - get changes into the bare clone.</div><p> - </p></li></ul></div><p> - </p></div><div class="section" title="B.1.2. Setting Up the Local Source Directory"><div class="titlepage"><div><div><h3 class="title"><a id="setting-up-the-local-yocto-project-files-git-repository"></a>B.1.2. Setting Up the Local Source Directory</h3></div></div></div><p> - You can set up the source directory through tarball extraction or by - cloning the <code class="filename">poky</code> Git repository. - This example uses <code class="filename">poky</code> as the root directory of the - local source directory. - See the bulleted item - "<a class="link" href="#local-yp-release">Yocto Project Release</a>" - for information on how to get these files. - </p><p> - Once you have source directory set up, - you have many development branches from which you can work. - From inside the local repository you can see the branch names and the tag names used - in the upstream Git repository by using either of the following commands: - </p><pre class="literallayout"> - $ cd poky - $ git branch -a - $ git tag -l - </pre><p> - This example uses the Yocto Project 1.3 Release code named "1.2+snapshot", - which maps to the <code class="filename">1.2+snapshot</code> branch in the repository. - The following commands create and checkout the local <code class="filename">1.2+snapshot</code> - branch: - </p><pre class="literallayout"> - $ git checkout -b 1.2+snapshot origin/1.2+snapshot - Branch 1.2+snapshot set up to track remote branch 1.2+snapshot from origin. - Switched to a new branch '1.2+snapshot' - </pre><p> - </p></div><div class="section" title="B.1.3. Setting Up the Local poky-extras Git Repository"><div class="titlepage"><div><div><h3 class="title"><a id="setting-up-the-poky-extras-git-repository"></a>B.1.3. Setting Up the Local poky-extras Git Repository</h3></div></div></div><p> - This example creates a local copy of the <code class="filename">poky-extras</code> Git - repository inside the <code class="filename">poky</code> source directory. - See the bulleted item "<a class="link" href="#poky-extras-repo">The - <code class="filename">poky-extras</code> Git Repository</a>" - for information on how to set up a local copy of the - <code class="filename">poky-extras</code> repository. - </p><p> - Because this example uses the Yocto Project 1.3 Release code - named "1.2+snapshot", which maps to the <code class="filename">1.2+snapshot</code> - branch in the repository, you need to be sure you are using that - branch for <code class="filename">poky-extra</code>. - The following commands create and checkout the local - branch you are using for the <code class="filename">1.2+snapshot</code> - branch: - </p><pre class="literallayout"> - $ git checkout -b 1.2+snapshot origin/1.2+snapshot - Branch 1.2+snapshot set up to track remote branch 1.2+snapshot from origin. - Switched to a new branch '1.2+snapshot' - </pre><p> - </p></div><div class="section" title="B.1.4. Setting Up the Bare Clone and its Copy"><div class="titlepage"><div><div><h3 class="title"><a id="setting-up-the-bare-clone-and-its-copy"></a>B.1.4. Setting Up the Bare Clone and its Copy</h3></div></div></div><p> - This example modifies the <code class="filename">linux-yocto-3.2</code> kernel. - Thus, you need to create a bare clone of that kernel and then make a copy of the - bare clone. - See the bulleted item - "<a class="link" href="#local-kernel-files">Yocto Project Kernel</a>" - for information on how to do that. - </p><p> - The bare clone exists for the kernel build tools and simply as the receiving end - of <code class="filename">git push</code> - commands after you make edits and commits inside the copy of the clone. - The copy (<code class="filename">my-linux-yocto-3.2-work</code> in this example) has to have - a local branch created and checked out for your work. - This example uses <code class="filename">common-pc-base</code> as the local branch. - The following commands create and checkout the branch: - </p><pre class="literallayout"> - $ cd ~/my-linux-yocto-3.2-work - $ git checkout -b common-pc-base origin/standard/default/common-pc/base - Checking out files: 100% (532/532), done. - Branch common-pc-base set up to track remote branch - standard/default/common-pc/base from origin. - Switched to a new branch 'common-pc-base' - </pre><p> - </p></div><div class="section" title="B.1.5. Building and Booting the Default QEMU Kernel Image"><div class="titlepage"><div><div><h3 class="title"><a id="building-and-booting-the-default-qemu-kernel-image"></a>B.1.5. Building and Booting the Default QEMU Kernel Image</h3></div></div></div><p> - Before we make changes to the kernel source files, this example first builds the - default image and then boots it inside the QEMU emulator. - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3> - Because a full build can take hours, you should check two variables in the - <code class="filename">build</code> directory that is created after you source the - <code class="filename">oe-init-build-env</code> script. - You can find these variables - <code class="filename">BB_NUMBER_THREADS</code> and <code class="filename">PARALLEL_MAKE</code> - in the <code class="filename">build/conf</code> directory in the - <code class="filename">local.conf</code> configuration file. - By default, these variables are commented out. - If your host development system supports multi-core and multi-thread capabilities, - you can uncomment these statements and set the variables to significantly shorten - the full build time. - As a guideline, set both <code class="filename">BB_NUMBER_THREADS</code> and - <code class="filename">PARALLEL_MAKE</code> to twice the number - of cores your machine supports. - </div><p> - The following two commands <code class="filename">source</code> the build environment setup script - and build the default <code class="filename">qemux86</code> image. - If necessary, the script creates the build directory: - </p><pre class="literallayout"> - $ cd ~/poky - $ source oe-init-build-env - - ### Shell environment set up for builds. ### - - You can now run 'bitbake <target>' - - Common targets are: - core-image-minimal - core-image-sato - meta-toolchain - meta-toolchain-sdk - adt-installer - meta-ide-support - - You can also run generated qemu images with a command like 'runqemu qemux86' - </pre><p> - </p><p> - The following <code class="filename">bitbake</code> command starts the build: - </p><pre class="literallayout"> - $ bitbake -k core-image-minimal - </pre><p> - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>Be sure to check the settings in the <code class="filename">local.conf</code> - before starting the build.</div><p> - </p><p> - After the build completes, you can start the QEMU emulator using the resulting image - <code class="filename">qemux86</code> as follows: - </p><pre class="literallayout"> - $ runqemu qemux86 - </pre><p> - </p><p> - As the image boots in the emulator, console message and status output appears - across the terminal window. - Because the output scrolls by quickly, it is difficult to read. - To examine the output, you log into the system using the - login <code class="filename">root</code> with no password. - Once you are logged in, issue the following command to scroll through the - console output: - </p><pre class="literallayout"> - # dmesg | less - </pre><p> - </p><p> - Take note of the output as you will want to look for your inserted print command output - later in the example. - </p></div><div class="section" title="B.1.6. Changing the Source Code and Pushing it to the Bare Clone"><div class="titlepage"><div><div><h3 class="title"><a id="changing-the-source-code-and-pushing-it-to-the-bare-clone"></a>B.1.6. Changing the Source Code and Pushing it to the Bare Clone</h3></div></div></div><p> - The file you change in this example is named <code class="filename">calibrate.c</code> - and is located in the <code class="filename">my-linux-yocto-3.2-work</code> Git repository - (the copy of the bare clone) in <code class="filename">init</code>. - This example simply inserts several <code class="filename">printk</code> statements - at the beginning of the <code class="filename">calibrate_delay</code> function. - </p><p> - Here is the unaltered code at the start of this function: - </p><pre class="literallayout"> - void __cpuinit calibrate_delay(void) - { - unsigned long lpj; - static bool printed; - int this_cpu = smp_processor_id(); - - if (per_cpu(cpu_loops_per_jiffy, this_cpu)) { - . - . - . - </pre><p> - </p><p> - Here is the altered code showing five new <code class="filename">printk</code> statements - near the top of the function: - </p><pre class="literallayout"> - void __cpuinit calibrate_delay(void) - { - unsigned long lpj; - static bool printed; - int this_cpu = smp_processor_id(); - - printk("*************************************\n"); - printk("* *\n"); - printk("* HELLO YOCTO KERNEL *\n"); - printk("* *\n"); - printk("*************************************\n"); - - if (per_cpu(cpu_loops_per_jiffy, this_cpu)) { - . - . - . - </pre><p> - </p><p> - After making and saving your changes, you need to stage them for the push. - The following Git commands are one method of staging and committing your changes: - </p><pre class="literallayout"> - $ git add calibrate.c - $ git commit --signoff - </pre><p> - </p><p> - Once the source code has been modified, you need to use Git to push the changes to - the bare clone. - If you do not push the changes, then the OpenEmbedded build system will not pick - up the changed source files. - </p><p> - The following command pushes the changes to the bare clone: - </p><pre class="literallayout"> - $ git push origin common-pc-base:standard/default/common-pc/base - </pre><p> - </p></div><div class="section" title="B.1.7. Changing Build Parameters for Your Build"><div class="titlepage"><div><div><h3 class="title"><a id="changing-build-parameters-for-your-build"></a>B.1.7. Changing Build Parameters for Your Build</h3></div></div></div><p> - At this point, the source has been changed and pushed. - The example now defines some variables used by the OpenEmbedded build system - to locate your kernel source. - You essentially need to identify where to find the kernel recipe and the changed source code. - You also need to be sure some basic configurations are in place that identify the - type of machine you are building and to help speed up the build should your host support - multiple-core and thread capabilities. - </p><p> - Do the following to make sure the build parameters are set up for the example. - Once you set up these build parameters, they do not have to change unless you - change the target architecture of the machine you are building or you move - the bare clone, copy of the clone, or the <code class="filename">poky-extras</code> repository: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><span class="emphasis"><em>Build for the Correct Target Architecture:</em></span> The - <code class="filename">local.conf</code> file in the build directory defines the build's - target architecture. - By default, <code class="filename">MACHINE</code> is set to - <code class="filename">qemux86</code>, which specifies a 32-bit - <span class="trademark">Intel</span>® Architecture - target machine suitable for the QEMU emulator. - In this example, <code class="filename">MACHINE</code> is correctly configured. - </p></li><li class="listitem"><p><span class="emphasis"><em>Optimize Build Time:</em></span> Also in the - <code class="filename">local.conf</code> file are two variables that can speed your - build time if your host supports multi-core and multi-thread capabilities: - <code class="filename">BB_NUMBER_THREADS</code> and <code class="filename">PARALLEL_MAKE</code>. - If the host system has multiple cores then you can optimize build time - by setting both these variables to twice the number of - cores.</p></li><li class="listitem"><p><span class="emphasis"><em>Identify Your <code class="filename">meta-kernel-dev</code> - Layer:</em></span> The <code class="filename">BBLAYERS</code> variable in the - <code class="filename">bblayers.conf</code> file found in the - <code class="filename">poky/build/conf</code> directory needs to have the path to your local - <code class="filename">meta-kernel-dev</code> layer. - By default, the <code class="filename">BBLAYERS</code> variable contains paths to - <code class="filename">meta</code> and <code class="filename">meta-yocto</code> in the - <code class="filename">poky</code> Git repository. - Add the path to your <code class="filename">meta-kernel-dev</code> location. - Be sure to substitute your user information in the statement. - Here is an example: - </p><pre class="literallayout"> - BBLAYERS = " \ - /home/scottrif/poky/meta \ - /home/scottrif/poky/meta-yocto \ - /home/scottrif/poky/poky-extras/meta-kernel-dev \ - " - </pre></li><li class="listitem"><p><span class="emphasis"><em>Identify Your Source Files:</em></span> In the - <code class="filename">linux-yocto_3.2.bbappend</code> file located in the - <code class="filename">poky-extras/meta-kernel-dev/recipes-kernel/linux</code> - directory, you need to identify the location of the - local source code, which in this example is the bare clone named - <code class="filename">linux-yocto-3.2.git</code>. - To do this, set the <code class="filename">KSRC_linux_yocto</code> variable to point to your - local <code class="filename">linux-yocto-3.2.git</code> Git repository by adding the - following statement. - Be sure to substitute your user information in the statement: - </p><pre class="literallayout"> - KSRC_linux_yocto_3_2 ?= "/home/scottrif/linux-yocto-3.2.git" - </pre></li></ul></div><p> - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>Before attempting to build the modified kernel, there is one more set of changes you - need to make in the <code class="filename">meta-kernel-dev</code> layer. - Because all the kernel <code class="filename">.bbappend</code> files are parsed during the - build process regardless of whether you are using them or not, you should either - comment out the <code class="filename">COMPATIBLE_MACHINE</code> statements in all - unused <code class="filename">.bbappend</code> files, or simply remove (or rename) all the files - except the one your are using for the build - (i.e. <code class="filename">linux-yocto_3.2.bbappend</code> in this example).</p><p>If you do not make one of these two adjustments, your machine will be compatible - with all the kernel recipes in the <code class="filename">meta-kernel-dev</code> layer. - When your machine is comapatible with all the kernel recipes, the build attempts - to build all kernels in the layer. - You could end up with build errors blocking your work.</p></div></div><div class="section" title="B.1.8. Building and Booting the Modified QEMU Kernel Image"><div class="titlepage"><div><div><h3 class="title"><a id="building-and-booting-the-modified-qemu-kernel-image"></a>B.1.8. Building and Booting the Modified QEMU Kernel Image</h3></div></div></div><p> - Next, you need to build the modified image. - Do the following: - </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Your environment should be set up since you previously sourced - the <code class="filename">oe-init-build-env</code> script. - If it isn't, source the script again from <code class="filename">poky</code>. - </p><pre class="literallayout"> - $ cd ~/poky - $ source oe-init-build-env - </pre><p> - </p></li><li class="listitem"><p>Be sure old images are cleaned out by running the - <code class="filename">cleanall</code> BitBake task as follows from your build directory: - </p><pre class="literallayout"> - $ bitbake -c cleanall linux-yocto - </pre><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>Never remove any files by hand from the <code class="filename">tmp/deploy</code> - directory insided the build directory. - Always use the BitBake <code class="filename">cleanall</code> task to clear - out previous builds.</div></li><li class="listitem"><p>Next, build the kernel image using this command: - </p><pre class="literallayout"> - $ bitbake -k core-image-minimal - </pre></li><li class="listitem"><p>Finally, boot the modified image in the QEMU emulator - using this command: - </p><pre class="literallayout"> - $ runqemu qemux86 - </pre></li></ol></div><p> - </p><p> - Log into the machine using <code class="filename">root</code> with no password and then - use the following shell command to scroll through the console's boot output. - </p><pre class="literallayout"> - # dmesg | less - </pre><p> - </p><p> - You should see the results of your <code class="filename">printk</code> statements - as part of the output. - </p></div></div><div class="section" title="B.2. Changing the Kernel Configuration"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="changing-the-kernel-configuration"></a>B.2. Changing the Kernel Configuration</h2></div></div></div><p> - This example changes the default behavior, which is "on", of the Symmetric - Multi-processing Support (<code class="filename">CONFIG_SMP</code>) to "off". - It is a simple example that demonstrates how to reconfigure the kernel. - </p><div class="section" title="B.2.1. Getting Set Up to Run this Example"><div class="titlepage"><div><div><h3 class="title"><a id="getting-set-up-to-run-this-example"></a>B.2.1. Getting Set Up to Run this Example</h3></div></div></div><p> - If you took the time to work through the example that modifies the kernel source code - in "<a class="link" href="#modifying-the-kernel-source-code" title="B.1. Modifying the Kernel Source Code">Modifying the Kernel Source - Code</a>" you should already have the source directory set up on your - host machine. - If this is the case, go to the next section, which is titled - "<a class="link" href="#examining-the-default-config-smp-behavior" title="B.2.2. Examining the Default CONFIG_SMP Behavior">Examining the Default - <code class="filename">CONFIG_SMP</code> Behavior</a>", and continue with the - example. - </p><p> - If you don't have the source directory established on your system, - you can get them through tarball extraction or by - cloning the <code class="filename">poky</code> Git repository. - This example uses <code class="filename">poky</code> as the root directory of the - <a class="link" href="#source-directory">source directory</a>. - See the bulleted item - "<a class="link" href="#local-yp-release">Yocto Project Release</a>" - for information on how to get these files. - </p><p> - Once you have the local copy of the repository set up, - you have many development branches from which you can work. - From inside the repository you can see the branch names and the tag names used - in the upstream Git repository using either of the following commands: - </p><pre class="literallayout"> - $ cd poky - $ git branch -a - $ git tag -l - </pre><p> - This example uses the Yocto Project 1.3 Release code named "1.2+snapshot", - which maps to the <code class="filename">1.2+snapshot</code> branch in the repository. - The following commands create and checkout the local <code class="filename">1.2+snapshot</code> - branch: - </p><pre class="literallayout"> - $ git checkout -b 1.2+snapshot origin/1.2+snapshot - Branch 1.2+snapshot set up to track remote branch 1.2+snapshot from origin. - Switched to a new branch '1.2+snapshot' - </pre><p> - </p><p> - Next, you need to build the default <code class="filename">qemux86</code> image that you - can boot using QEMU. - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3> - Because a full build can take hours, you should check two variables in the - <code class="filename">build</code> directory that is created after you source the - <code class="filename">oe-init-build-env</code> script. - You can find these variables - <code class="filename">BB_NUMBER_THREADS</code> and <code class="filename">PARALLEL_MAKE</code> - in the <code class="filename">build/conf</code> directory in the - <code class="filename">local.conf</code> configuration file. - By default, these variables are commented out. - If your host development system supports multi-core and multi-thread capabilities, - you can uncomment these statements and set the variables to significantly shorten - the full build time. - As a guideline, set both the <code class="filename">BB_NUMBER_THREADS</code> and the - <code class="filename">PARALLEL_MAKE</code> variables to twice the number - of cores your machine supports. - </div><p> - The following two commands <code class="filename">source</code> the build environment setup script - and build the default <code class="filename">qemux86</code> image. - If necessary, the script creates the build directory: - </p><pre class="literallayout"> - $ cd ~/poky - $ source oe-init-build-env - - ### Shell environment set up for builds. ### - - You can now run 'bitbake <target>' - - Common targets are: - core-image-minimal - core-image-sato - meta-toolchain - meta-toolchain-sdk - adt-installer - meta-ide-support - - You can also run generated qemu images with a command like 'runqemu qemux86' - </pre><p> - </p><p> - The following <code class="filename">bitbake</code> command starts the build: - </p><pre class="literallayout"> - $ bitbake -k core-image-minimal - </pre><p> - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>Be sure to check the settings in the <code class="filename">local.conf</code> - before starting the build.</div><p> - </p></div><div class="section" title="B.2.2. Examining the Default CONFIG_SMP Behavior"><div class="titlepage"><div><div><h3 class="title"><a id="examining-the-default-config-smp-behavior"></a>B.2.2. Examining the Default <code class="filename">CONFIG_SMP</code> Behavior</h3></div></div></div><p> - By default, <code class="filename">CONFIG_SMP</code> supports multiple processor machines. - To see this default setting from within the QEMU emulator, boot your image using - the emulator as follows: - </p><pre class="literallayout"> - $ runqemu qemux86 qemuparams="-smp 4" - </pre><p> - </p><p> - Login to the machine using <code class="filename">root</code> with no password. - After logging in, enter the following command to see how many processors are - being supported in the emulator. - The emulator reports support for the number of processors you specified using - the <code class="filename">-smp</code> option, four in this case: - </p><pre class="literallayout"> - # cat /proc/cpuinfo | grep processor - processor : 0 - processor : 1 - processor : 2 - processor : 3 - # - </pre><p> - To check the setting for <code class="filename">CONFIG_SMP</code>, you can use the - following command: - </p><pre class="literallayout"> - zcat /proc/config.gz | grep CONFIG_SMP - </pre><p> - The console returns the following showing that multi-processor machine support - is set: - </p><pre class="literallayout"> - CONFIG_SMP=y - </pre><p> - Logout of the emulator using the <code class="filename">exit</code> command and - then close it down. - </p></div><div class="section" title="B.2.3. Changing the CONFIG_SMP Configuration Using menuconfig"><div class="titlepage"><div><div><h3 class="title"><a id="changing-the-config-smp-configuration-using-menuconfig"></a>B.2.3. Changing the <code class="filename">CONFIG_SMP</code> Configuration Using <code class="filename">menuconfig</code></h3></div></div></div><p> - The <code class="filename">menuconfig</code> tool provides an interactive method with which - to set kernel configurations. - You need to run <code class="filename">menuconfig</code> inside the Yocto BitBake environment. - Thus, the environment must be set up using the <code class="filename">oe-init-build-env</code> - script found in the build directory. - If you have not sourced this script do so with the following commands: - </p><pre class="literallayout"> - $ cd ~/poky - $ source oe-init-build-env - </pre><p> - </p><p> - After setting up the environment to run <code class="filename">menuconfig</code>, you are ready - to use the tool to interactively change the kernel configuration. - In this example, we are basing our changes on the <code class="filename">linux-yocto-3.2</code> - kernel. - The OpenEmbedded build system recognizes this kernel as - <code class="filename">linux-yocto</code>. - Thus, the following commands from the shell in which you previously sourced the - environment initialization script cleans the shared state cache and the - <a class="link" href="#var-WORKDIR" target="_top"><code class="filename">WORKDIR</code></a> - directory and then builds and launches <code class="filename">menuconfig</code>: - </p><pre class="literallayout"> - $ bitbake linux-yocto -c menuconfig - </pre><p> - </p><p> - Once <code class="filename">menuconfig</code> launches, navigate through the user interface - to find the <code class="filename">CONFIG_SMP</code> configuration setting. - You can find it at <code class="filename">Processor Type and Features</code>. - The configuration selection is - <code class="filename">Symmetric Multi-processing Support</code>. - After using the arrow keys to highlight this selection, press "n" to turn it off. - Then, exit out and save your selections. - </p><p> - Once you save the selection, the <code class="filename">.config</code> configuration file - is updated. - This is the file that the build system uses to configure the Yocto Project kernel - when it is built. - You can find and examine this file in the build directory. - This example uses the following: - </p><pre class="literallayout"> - ~/poky/build/tmp/work/qemux86-poky-linux/linux-yocto-3.2.11+git1+84f... - ...656ed30-r1/linux-qemux86-standard-build - </pre><p> - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3> - The previous example directory is artificially split and many of the characters - in the actual filename are omitted in order to make it more readable. - Also, depending on the kernel you are using, the exact pathname might differ - slightly. - </div><p> - </p><p> - Within the <code class="filename">.config</code> file, you can see the following setting: - </p><pre class="literallayout"> - # CONFIG_SMP is not set - </pre><p> - </p><p> - A good method to isolate changed configurations is to use a combination of the - <code class="filename">menuconfig</code> tool and simple shell commands. - Before changing configurations with <code class="filename">menuconfig</code>, copy the - existing <code class="filename">.config</code> and rename it to something else, - use <code class="filename">menuconfig</code> to make - as many changes an you want and save them, then compare the renamed configuration - file against the newly created file. - You can use the resulting differences as your base to create configuration fragments - to permanently save in your kernel layer. - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3> - Be sure to make a copy of the <code class="filename">.config</code> and don't just - rename it. - The build system needs an existing <code class="filename">.config</code> - from which to work. - </div><p> - </p></div><div class="section" title="B.2.4. Recompiling the Kernel and Testing the New Configuration"><div class="titlepage"><div><div><h3 class="title"><a id="recompiling-the-kernel-and-testing-the-new-configuration"></a>B.2.4. Recompiling the Kernel and Testing the New Configuration</h3></div></div></div><p> - At this point, you are ready to recompile your kernel image with - the new setting in effect using the BitBake command below: - </p><pre class="literallayout"> - $ bitbake linux-yocto - </pre><p> - </p><p> - Now run the QEMU emulator and pass it the same multi-processor option as before: - </p><pre class="literallayout"> - $ runqemu qemux86 qemuparams="-smp 4" - </pre><p> - </p><p> - Login to the machine using <code class="filename">root</code> with no password - and test for the number of processors the kernel supports: - </p><pre class="literallayout"> - # cat /proc/cpuinfo | grep processor - processor : 0 - # - </pre><p> - </p><p> - From the output, you can see that the kernel no longer supports multi-processor systems. - The output indicates support for a single processor. You can verify the - <code class="filename">CONFIG_SMP</code> setting by using this command: - </p><pre class="literallayout"> - zcat /proc/config.gz | grep CONFIG_SMP - </pre><p> - The console returns the following output: - </p><pre class="literallayout"> - # CONFIG_SMP is not set - </pre><p> - You have successfully reconfigured the kernel. - </p></div></div><div class="section" title="B.3. Adding Kernel Recipes"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="adding-kernel-recipes"></a>B.3. Adding Kernel Recipes</h2></div></div></div><p> - A future release of this manual will present an example that adds kernel recipes, which provide - new functionality to the kernel. - </p><p> - </p><table border="0" summary="manufactured viewport for HTML img" cellspacing="0" cellpadding="0" width="180"><tr style="height: 270px"><td align="center"><img src="figures/wip.png" align="middle" width="180" /></td></tr></table><p> - </p></div></div> - -</div> - -<table border="0" summary="manufactured viewport for HTML img" cellspacing="0" cellpadding="0" width="100%"><tr><td align="left"><img src="figures/adt-title.png" align="left" width="100%" /></td></tr></table> - - <div xml:lang="en" class="book" lang="en"><div class="titlepage"><div><div><h1 class="title"><a id="adt-manual"></a></h1></div><div><div class="authorgroup"> - <div class="author"><h3 class="author"><span class="firstname">Jessica</span> <span class="surname">Zhang</span></h3><div class="affiliation"> - <span class="orgname">Intel Corporation<br /></span> - </div><code class="email"><<a class="email" href="mailto:jessica.zhang@intel.com">jessica.zhang@intel.com</a>></code></div> - </div></div><div><p class="copyright">Copyright © 2010-2012 Linux Foundation</p></div><div><div class="legalnotice" title="Legal Notice"><a id="id1499739"></a> - <p> - Permission is granted to copy, distribute and/or modify this document under - the terms of the <a class="ulink" href="http://creativecommons.org/licenses/by-sa/2.0/uk/" target="_top">Creative Commons Attribution-Share Alike 2.0 UK: England & Wales</a> as published by Creative Commons. - </p> - <div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3> - Due to production processes, there could be differences between the Yocto Project - documentation bundled in the release tarball and the - Yocto Project Application Developer's Guide on - the <a class="ulink" href="http://www.yoctoproject.org" target="_top">Yocto Project</a> website. - For the latest version of this manual, see the manual on the website. - </div> - - </div></div><div><div class="revhistory"><table border="1" width="100%" summary="Revision history"><tr><th align="left" valign="top" colspan="2"><b>Revision History</b></th></tr> - <tr><td align="left">Revision 1.0</td><td align="left">6 April 2011</td></tr><tr><td align="left" colspan="2">Released with the Yocto Project 1.0 Release.</td></tr> - <tr><td align="left">Revision 1.0.1</td><td align="left">23 May 2011</td></tr><tr><td align="left" colspan="2">Released with the Yocto Project 1.0.1 Release.</td></tr> - <tr><td align="left">Revision 1.1</td><td align="left">6 October 2011</td></tr><tr><td align="left" colspan="2">Released with the Yocto Project 1.1 Release.</td></tr> - <tr><td align="left">Revision 1.2</td><td align="left">April 2012</td></tr><tr><td align="left" colspan="2">Released with the Yocto Project 1.2 Release.</td></tr> - <tr><td align="left">Revision 1.3</td><td align="left">Sometime in 2012</td></tr><tr><td align="left" colspan="2">Released with the Yocto Project 1.3 Release.</td></tr> - </table></div></div></div><hr /></div> - - - <div class="chapter" title="Chapter 1. Introduction"><div class="titlepage"><div><div><h2 class="title"><a id="adt-intro"></a>Chapter 1. Introduction</h2></div></div></div><div class="toc"><dl><dt><span class="section"><a href="#adt-intro-section">1.1. The Application Development Toolkit (ADT)</a></span></dt><dd><dl><dt><span class="section"><a href="#the-cross-toolchain">1.1.1. The Cross-Toolchain</a></span></dt><dt><span class="section"><a href="#sysroot">1.1.2. Sysroot</a></span></dt><dt><span class="section"><a href="#eclipse-overview">1.1.3. Eclipse Yocto Plug-in</a></span></dt><dt><span class="section"><a href="#the-qemu-emulator">1.1.4. The QEMU Emulator</a></span></dt><dt><span class="section"><a href="#user-space-tools">1.1.5. User-Space Tools</a></span></dt></dl></dd></dl></div><p> - Welcome to the Yocto Project Application Developer's Guide. - This manual provides information that lets you begin developing applications - using the Yocto Project. -</p><p> - The Yocto Project provides an application development environment based on - an Application Development Toolkit (ADT) and the availability of stand-alone - cross-development toolchains and other tools. - This manual describes the ADT and how you can configure and install it, - how to access and use the cross-development toolchains, how to - customize the development packages installation, - how to use command line development for both Autotools-based and Makefile-based projects, - and an introduction to the Eclipse Yocto Plug-in. -</p><div class="section" title="1.1. The Application Development Toolkit (ADT)"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="adt-intro-section"></a>1.1. The Application Development Toolkit (ADT)</h2></div></div></div><p> - Part of the Yocto Project development solution is an Application Development - Toolkit (ADT). - The ADT provides you with a custom-built, cross-development - platform suited for developing a user-targeted product application. - </p><p> - Fundamentally, the ADT consists of the following: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>An architecture-specific cross-toolchain and matching - sysroot both built by the OpenEmbedded build system, which uses Poky. - The toolchain and sysroot are based on a metadata configuration and extensions, - which allows you to cross-develop on the host machine for the target hardware. - </p></li><li class="listitem"><p>The Eclipse IDE Yocto Plug-in.</p></li><li class="listitem"><p>The Quick EMUlator (QEMU), which lets you simulate target hardware. - </p></li><li class="listitem"><p>Various user-space tools that greatly enhance your application - development experience.</p></li></ul></div><p> - </p><div class="section" title="1.1.1. The Cross-Toolchain"><div class="titlepage"><div><div><h3 class="title"><a id="the-cross-toolchain"></a>1.1.1. The Cross-Toolchain</h3></div></div></div><p> - The cross-toolchain consists of a cross-compiler, cross-linker, and cross-debugger - that are used to develop user-space applications for targeted hardware. - This toolchain is created either by running the ADT Installer script or - through a build directory that is based on your metadata - configuration or extension for your targeted device. - The cross-toolchain works with a matching target sysroot. - </p></div><div class="section" title="1.1.2. Sysroot"><div class="titlepage"><div><div><h3 class="title"><a id="sysroot"></a>1.1.2. Sysroot</h3></div></div></div><p> - The matching target sysroot contains needed headers and libraries for generating - binaries that run on the target architecture. - The sysroot is based on the target root filesystem image that is built by - the OpenEmbedded build system Poky and uses the same metadata configuration - used to build the cross-toolchain. - </p></div><div class="section" title="1.1.3. Eclipse Yocto Plug-in"><div class="titlepage"><div><div><h3 class="title"><a id="eclipse-overview"></a>1.1.3. Eclipse Yocto Plug-in</h3></div></div></div><p> - The Eclipse IDE is a popular development environment and it fully supports - development using the Yocto Project. - When you install and configure the Eclipse Yocto Project Plug-in into - the Eclipse IDE, you maximize your Yocto Project experience. - Installing and configuring the Plug-in results in an environment that - has extensions specifically designed to let you more easily develop software. - These extensions allow for cross-compilation, deployment, and execution of - your output into a QEMU emulation session. - You can also perform cross-debugging and profiling. - The environment also supports a suite of tools that allows you to perform - remote profiling, tracing, collection of power data, collection of - latency data, and collection of performance data. - </p><p> - For information about the application development workflow that uses the Eclipse - IDE and for a detailed example of how to install and configure the Eclipse - Yocto Project Plug-in, see the - "<a class="link" href="#adt-eclipse" target="_top">Working Within Eclipse</a>" section - of the Yocto Project Development Manual. - </p></div><div class="section" title="1.1.4. The QEMU Emulator"><div class="titlepage"><div><div><h3 class="title"><a id="the-qemu-emulator"></a>1.1.4. The QEMU Emulator</h3></div></div></div><p> - The QEMU emulator allows you to simulate your hardware while running your - application or image. - QEMU is made available a number of ways: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>If you use the ADT Installer script to install ADT, you can - specify whether or not to install QEMU.</p></li><li class="listitem"><p>If you have downloaded a Yocto Project release and unpacked - it to create a source directory and you have sourced - the environment setup script, QEMU is installed and automatically - available.</p></li><li class="listitem"><p>If you have installed the cross-toolchain - tarball and you have sourcing the toolchain's setup environment script, QEMU - is also installed and automatically available.</p></li></ul></div><p> - </p></div><div class="section" title="1.1.5. User-Space Tools"><div class="titlepage"><div><div><h3 class="title"><a id="user-space-tools"></a>1.1.5. User-Space Tools</h3></div></div></div><p> - User-space tools are included as part of the distribution. - You will find these tools helpful during development. - The tools include LatencyTOP, PowerTOP, OProfile, Perf, SystemTap, and Lttng-ust. - These tools are common development tools for the Linux platform. - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><span class="emphasis"><em>LatencyTOP:</em></span> LatencyTOP focuses on latency - that causes skips in audio, - stutters in your desktop experience, or situations that overload your server - even when you have plenty of CPU power left. - You can find out more about LatencyTOP at - <a class="ulink" href="http://www.latencytop.org/" target="_top">http://www.latencytop.org/</a>.</p></li><li class="listitem"><p><span class="emphasis"><em>PowerTOP:</em></span> Helps you determine what - software is using the most power. - You can find out more about PowerTOP at - <a class="ulink" href="http://www.linuxpowertop.org/" target="_top">http://www.linuxpowertop.org/</a>.</p></li><li class="listitem"><p><span class="emphasis"><em>OProfile:</em></span> A system-wide profiler for Linux - systems that is capable of profiling all running code at low overhead. - You can find out more about OProfile at - <a class="ulink" href="http://oprofile.sourceforge.net/about/" target="_top">http://oprofile.sourceforge.net/about/</a>.</p></li><li class="listitem"><p><span class="emphasis"><em>Perf:</em></span> Performance counters for Linux used - to keep track of certain types of hardware and software events. - For more information on these types of counters see - <a class="ulink" href="https://perf.wiki.kernel.org/" target="_top">https://perf.wiki.kernel.org/</a> and click - on “Perf tools.”</p></li><li class="listitem"><p><span class="emphasis"><em>SystemTap:</em></span> A free software infrastructure - that simplifies information gathering about a running Linux system. - This information helps you diagnose performance or functional problems. - SystemTap is not available as a user-space tool through the Eclipse IDE Yocto Plug-in. - See <a class="ulink" href="http://sourceware.org/systemtap" target="_top">http://sourceware.org/systemtap</a> for more information - on SystemTap.</p></li><li class="listitem"><p><span class="emphasis"><em>Lttng-ust:</em></span> A User-space Tracer designed to - provide detailed information on user-space activity. - See <a class="ulink" href="http://lttng.org/ust" target="_top">http://lttng.org/ust</a> for more information on Lttng-ust. - </p></li></ul></div><p> - </p></div></div></div> - - <div class="chapter" title="Chapter 2. Preparing for Application Development"><div class="titlepage"><div><div><h2 class="title"><a id="adt-prepare"></a>Chapter 2. Preparing for Application Development</h2></div></div></div><div class="toc"><dl><dt><span class="section"><a href="#installing-the-adt">2.1. Installing the ADT and Toolchains</a></span></dt><dd><dl><dt><span class="section"><a href="#using-the-adt-installer">2.1.1. Using the ADT Installer</a></span></dt><dt><span class="section"><a href="#using-an-existing-toolchain-tarball">2.1.2. Using a Cross-Toolchain Tarball</a></span></dt><dt><span class="section"><a href="#using-the-toolchain-from-within-the-build-tree">2.1.3. Using BitBake and the Build Directory</a></span></dt></dl></dd><dt><span class="section"><a href="#setting-up-the-cross-development-environment">2.2. Setting Up the Cross-Development Environment</a></span></dt><dt><span class="section"><a href="#securing-kernel-and-filesystem-images">2.3. Securing Kernel and Filesystem Images</a></span></dt><dd><dl><dt><span class="section"><a href="#getting-the-images">2.3.1. Getting the Images</a></span></dt><dt><span class="section"><a href="#extracting-the-root-filesystem">2.3.2. Extracting the Root Filesystem</a></span></dt></dl></dd></dl></div><p> - In order to develop applications, you need set up your host development system. - Several ways exist that allow you to install cross-development tools, QEMU, the - Eclipse Yocto Plug-in, and other tools. - This chapter describes how to prepare for application development. -</p><div class="section" title="2.1. Installing the ADT and Toolchains"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="installing-the-adt"></a>2.1. Installing the ADT and Toolchains</h2></div></div></div><p> - The following list describes installation methods that set up varying degrees of tool - availabiltiy on your system. - Regardless of the installation method you choose, - you must <code class="filename">source</code> the cross-toolchain - environment setup script before you use a toolchain. - See the "<a class="link" href="#setting-up-the-cross-development-environment" title="2.2. Setting Up the Cross-Development Environment">Setting Up the - Cross-Development Environment</a>" section for more information. - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>Avoid mixing installation methods when installing toolchains for different architectures. - For example, avoid using the ADT Installer to install some toolchains and then hand-installing - cross-development toolchains from downloaded tarballs to install toolchains - for different architectures. - Mixing installation methods can result in situations where the ADT Installer becomes - unreliable and might not install the toolchain.</p><p>If you must mix installation methods, you might avoid problems by deleting - <code class="filename">/var/lib/opkg</code>, thus purging the <code class="filename">opkg</code> package - metadata</p></div><p> - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><span class="emphasis"><em>Use the ADT Installer Script:</em></span> - This method is the recommended way to install the ADT because it - automates much of the process for you. - For example, you can configure the installation to install the QEMU emulator - and the user-space NFS, specify which root filesystem profiles to download, - and define the target sysroot location.</p></li><li class="listitem"><p><span class="emphasis"><em>Use an Existing Toolchain Tarball:</em></span> - Using this method, you select and download an architecture-specific - toolchain tarball and then hand-install the toolchain. - If you use this method, you just get the cross-toolchain and QEMU - you do not - get any of the other mentioned benefits had you run the ADT Installer script.</p></li><li class="listitem"><p><span class="emphasis"><em>Use the Toolchain from within the Build Directory:</em></span> - If you already have a - <a class="link" href="#build-directory" target="_top">build directory</a>, - you can build the cross-toolchain within the directory. - However, like the previous method mentioned, you only get the cross-toolchain and QEMU - you - do not get any of the other benefits without taking separate steps.</p></li></ul></div><p> - </p><div class="section" title="2.1.1. Using the ADT Installer"><div class="titlepage"><div><div><h3 class="title"><a id="using-the-adt-installer"></a>2.1.1. Using the ADT Installer</h3></div></div></div><p> - To run the ADT Installer, you need to first get the ADT Installer tarball and then run the ADT - Installer Script. - </p><div class="section" title="2.1.1.1. Getting the ADT Installer Tarball"><div class="titlepage"><div><div><h4 class="title"><a id="getting-the-adt-installer-tarball"></a>2.1.1.1. Getting the ADT Installer Tarball</h4></div></div></div><p> - The ADT Installer is contained in the ADT Installer tarball. - You can download the tarball into any directory from the - <a class="ulink" href="http://downloads.yoctoproject.org/releases" target="_top">Index of Releases</a>, specifically - at - <a class="ulink" href="http://downloads.yoctoproject.org/releases/yocto/yocto-1.3/adt_installer" target="_top">http://downloads.yoctoproject.org/releases/yocto/yocto-1.3/adt_installer</a>. - Or, you can use BitBake to generate the tarball inside the existing - <a class="link" href="#build-directory" target="_top">build directory</a>. - </p><p> - If you use BitBake to generate the ADT Installer tarball, you must - <code class="filename">source</code> the environment setup script - (<code class="filename">oe-init-build-env</code>) located - in the source directory before running the <code class="filename">bitbake</code> - command that creates the tarball. - </p><p> - The following example commands download the Poky tarball, set up the - <a class="link" href="#source-directory" target="_top">source directory</a>, - set up the environment while also creating the default build directory, - and run the <code class="filename">bitbake</code> command that results in the tarball - <code class="filename">~/yocto-project/build/tmp/deploy/sdk/adt_installer.tar.bz2</code>: - </p><pre class="literallayout"> - $ cd ~ - $ mkdir yocto-project - $ cd yocto-project - $ wget http://downloads.yoctoproject.org/releases/yocto/yocto-1.3/poky-1.2+snapshot-8.0.tar.bz2 - $ tar xjf poky-1.2+snapshot-8.0.tar.bz2 - $ source poky-1.2+snapshot-8.0/oe-init-build-env - $ bitbake adt-installer - </pre><p> - </p></div><div class="section" title="2.1.1.2. Configuring and Running the ADT Installer Script"><div class="titlepage"><div><div><h4 class="title"><a id="configuring-and-running-the-adt-installer-script"></a>2.1.1.2. Configuring and Running the ADT Installer Script</h4></div></div></div><p> - Before running the ADT Installer script, you need to unpack the tarball. - You can unpack the tarball in any directory you wish. - For example, this command copies the ADT Installer tarball from where - it was built into the home directory and then unpacks the tarball into - a top-level directory named <code class="filename">adt-installer</code>: - </p><pre class="literallayout"> - $ cd ~ - $ cp ~/poky/build/tmp/deploy/sdk/adt_installer.tar.bz2 $HOME - $ tar -xjf adt_installer.tar.bz2 - </pre><p> - Unpacking it creates the directory <code class="filename">adt-installer</code>, - which contains the ADT Installer script (<code class="filename">adt_installer</code>) - and its configuration file (<code class="filename">adt_installer.conf</code>). - </p><p> - Before you run the script, however, you should examine the ADT Installer configuration - file and be sure you are going to get what you want. - Your configurations determine which kernel and filesystem image are downloaded. - </p><p> - The following list describes the configurations you can define for the ADT Installer. - For configuration values and restrictions, see the comments in - the <code class="filename">adt-installer.conf</code> file: - - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><code class="filename">YOCTOADT_REPO</code>: This area - includes the IPKG-based packages and the root filesystem upon which - the installation is based. - If you want to set up your own IPKG repository pointed to by - <code class="filename">YOCTOADT_REPO</code>, you need to be sure that the - directory structure follows the same layout as the reference directory - set up at <a class="ulink" href="http://adtrepo.yoctoproject.org" target="_top">http://adtrepo.yoctoproject.org</a>. - Also, your repository needs to be accessible through HTTP.</p></li><li class="listitem"><p><code class="filename">YOCTOADT_TARGETS</code>: The machine - target architectures for which you want to set up cross-development - environments.</p></li><li class="listitem"><p><code class="filename">YOCTOADT_QEMU</code>: Indicates whether - or not to install the emulator QEMU.</p></li><li class="listitem"><p><code class="filename">YOCTOADT_NFS_UTIL</code>: Indicates whether - or not to install user-mode NFS. - If you plan to use the Eclipse IDE Yocto plug-in against QEMU, - you should install NFS. - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>To boot QEMU images using our userspace NFS server, you need - to be running <code class="filename">portmap</code> or <code class="filename">rpcbind</code>. - If you are running <code class="filename">rpcbind</code>, you will also need to add the - <code class="filename">-i</code> option when <code class="filename">rpcbind</code> starts up. - Please make sure you understand the security implications of doing this. - You might also have to modify your firewall settings to allow - NFS booting to work.</div></li><li class="listitem"><p><code class="filename">YOCTOADT_ROOTFS_<arch></code>: The root - filesystem images you want to download from the - <code class="filename">YOCTOADT_IPKG_REPO</code> repository.</p></li><li class="listitem"><p><code class="filename">YOCTOADT_TARGET_SYSROOT_IMAGE_<arch></code>: The - particular root filesystem used to extract and create the target sysroot. - The value of this variable must have been specified with - <code class="filename">YOCTOADT_ROOTFS_<arch></code>. - For example, if you downloaded both <code class="filename">minimal</code> and - <code class="filename">sato-sdk</code> images by setting - <code class="filename">YOCTOADT_ROOTFS_<arch></code> - to "minimal sato-sdk", then <code class="filename">YOCTOADT_ROOTFS_<arch></code> - must be set to either <code class="filename">minimal</code> or - <code class="filename">sato-sdk</code>.</p></li><li class="listitem"><p><code class="filename">YOCTOADT_TARGET_SYSROOT_LOC_<arch></code>: The - location on the development host where the target sysroot is created. - </p></li></ul></div><p> - </p><p> - After you have configured the <code class="filename">adt_installer.conf</code> file, - run the installer using the following command. - Be sure that you are not trying to use cross-compilation tools. - When you run the installer, the environment must use a - host <code class="filename">gcc</code>: - </p><pre class="literallayout"> - $ ./adt_installer - </pre><p> - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3> - The ADT Installer requires the <code class="filename">libtool</code> package to complete. - If you install the recommended packages as described in - "<a class="link" href="#packages" target="_top">The Packages</a>" - section of the Yocto Project Quick Start, then you will have libtool installed. - </div><p> - Once the installer begins to run, you are asked whether you want to run in - interactive or silent mode. - If you want to closely monitor the installation, choose “I” for interactive - mode rather than “S” for silent mode. - Follow the prompts from the script to complete the installation. - </p><p> - Once the installation completes, the ADT, which includes the cross-toolchain, is installed. - You will notice environment setup files for the cross-toolchain in - <code class="filename">/opt/poky/1.3</code>, - and image tarballs in the <code class="filename">adt-installer</code> - directory according to your installer configurations, and the target sysroot located - according to the <code class="filename">YOCTOADT_TARGET_SYSROOT_LOC_<arch></code> variable - also in your configuration file. - </p></div></div><div class="section" title="2.1.2. Using a Cross-Toolchain Tarball"><div class="titlepage"><div><div><h3 class="title"><a id="using-an-existing-toolchain-tarball"></a>2.1.2. Using a Cross-Toolchain Tarball</h3></div></div></div><p> - If you want to simply install the cross-toolchain by hand, you can do so by using an existing - cross-toolchain tarball. - If you use this method to install the cross-toolchain and you still need to install the target - sysroot, you will have to install sysroot separately. - </p><p> - Follow these steps: - </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Go to - <a class="ulink" href="http://downloads.yoctoproject.org/releases/yocto/yocto-1.3/toolchain/" target="_top">http://downloads.yoctoproject.org/releases/yocto/yocto-1.3/toolchain/</a> - and find the folder that matches your host development system - (i.e. <code class="filename">i686</code> for 32-bit machines or - <code class="filename">x86-64</code> for 64-bit machines).</p></li><li class="listitem"><p>Go into that folder and download the toolchain tarball whose name - includes the appropriate target architecture. - For example, if your host development system is an Intel-based 64-bit system and - you are going to use your cross-toolchain for an Intel-based 32-bit target, go into the - <code class="filename">x86_64</code> folder and download the following tarball: - </p><pre class="literallayout"> - poky-eglibc-x86_64-i586-toolchain-gmae-1.3.tar.bz2 - </pre><p> - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>As an alternative to steps one and two, you can build the toolchain tarball - if you have a <a class="link" href="#build-directory" target="_top">build directory</a>. - If you need GMAE, you should use the <code class="filename">bitbake meta-toolchain-gmae</code> - command. - The resulting tarball will support such development. - However, if you are not concerned with GMAE, - you can generate the tarball using <code class="filename">bitbake meta-toolchain</code>.</p><p>Use the appropriate <code class="filename">bitbake</code> command only after you have - sourced the <code class="filename">oe-build-init-env</code> script located in the source - directory. - When the <code class="filename">bitbake</code> command completes, the tarball will - be in <code class="filename">tmp/deploy/sdk</code> in the build directory. - </p></div></li><li class="listitem"><p>Make sure you are in the root directory with root privileges and then expand - the tarball. - The tarball expands into <code class="filename">/opt/poky/1.3</code>. - Once the tarball is expanded, the cross-toolchain is installed. - You will notice environment setup files for the cross-toolchain in the directory. - </p></li></ol></div><p> - </p></div><div class="section" title="2.1.3. Using BitBake and the Build Directory"><div class="titlepage"><div><div><h3 class="title"><a id="using-the-toolchain-from-within-the-build-tree"></a>2.1.3. Using BitBake and the Build Directory</h3></div></div></div><p> - A final way of making the cross-toolchain available is to use BitBake - to generate the toolchain within an existing - <a class="link" href="#build-directory" target="_top">build directory</a>. - This method does not install the toolchain into the - <code class="filename">/opt</code> directory. - As with the previous method, if you need to install the target sysroot, you must - do that separately as well. - </p><p> - Follow these steps to generate the toolchain into the build directory: - </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Source the environment setup script - <code class="filename">oe-init-build-env</code> located in the - <a class="link" href="#source-directory" target="_top">source directory</a>. - </p></li><li class="listitem"><p>At this point, you should be sure that the - <a class="link" href="#var-MACHINE" target="_top"><code class="filename">MACHINE</code></a> variable - in the <code class="filename">local.conf</code> file found in the - <code class="filename">conf</code> directory of the build directory - is set for the target architecture. - Comments within the <code class="filename">local.conf</code> file list the values you - can use for the <code class="filename">MACHINE</code> variable. - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>You can populate the build directory with the cross-toolchains for more - than a single architecture. - You just need to edit the <code class="filename">MACHINE</code> variable in the - <code class="filename">local.conf</code> file and re-run the BitBake - command.</div></li><li class="listitem"><p>Run <code class="filename">bitbake meta-ide-support</code> to complete the - cross-toolchain generation. - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>If you change out of your working directory after you - <code class="filename">source</code> the environment setup script and before you run - the <code class="filename">bitbake</code> command, the command might not work. - Be sure to run the <code class="filename">bitbake</code> command immediately - after checking or editing the <code class="filename">local.conf</code> but without - changing out of your working directory.</div><p> - Once the <code class="filename">bitbake</code> command finishes, - the cross-toolchain is generated and populated within the build directory. - You will notice environment setup files for the cross-toolchain in the - build directory in the <code class="filename">tmp</code> directory. - Setup script filenames contain the strings <code class="filename">environment-setup</code>. - </p></li></ol></div><p> - </p></div></div><div class="section" title="2.2. Setting Up the Cross-Development Environment"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="setting-up-the-cross-development-environment"></a>2.2. Setting Up the Cross-Development Environment</h2></div></div></div><p> - Before you can develop using the cross-toolchain, you need to set up the - cross-development environment by sourcing the toolchain's environment setup script. - If you used the ADT Installer or hand-installed cross-toolchain, - then you can find this script in the <code class="filename">/opt/poky/1.3</code> - directory. - If you installed the toolchain in the - <a class="link" href="#build-directory" target="_top">build directory</a>, - you can find the environment setup - script for the toolchain in the build directory's <code class="filename">tmp</code> directory. - </p><p> - Be sure to run the environment setup script that matches the architecture for - which you are developing. - Environment setup scripts begin with the string “<code class="filename">environment-setup</code>” - and include as part of their name the architecture. - For example, the toolchain environment setup script for a 64-bit IA-based architecture would - be the following: - </p><pre class="literallayout"> - /opt/poky/1.3/environment-setup-x86_64-poky-linux - </pre><p> - </p></div><div class="section" title="2.3. Securing Kernel and Filesystem Images"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="securing-kernel-and-filesystem-images"></a>2.3. Securing Kernel and Filesystem Images</h2></div></div></div><p> - You will need to have a kernel and filesystem image to boot using your - hardware or the QEMU emulator. - Furthermore, if you plan on booting your image using NFS or you want to use the root filesystem - as the target sysroot, you need to extract the root filesystem. - </p><div class="section" title="2.3.1. Getting the Images"><div class="titlepage"><div><div><h3 class="title"><a id="getting-the-images"></a>2.3.1. Getting the Images</h3></div></div></div><p> - To get the kernel and filesystem images, you either have to build them or download - pre-built versions. - You can find examples for both these situations in the - "<a class="link" href="#test-run" target="_top">A Quick Test Run</a>" section of - the Yocto Project Quick Start. - </p><p> - The Yocto Project ships basic kernel and filesystem images for several - architectures (<code class="filename">x86</code>, <code class="filename">x86-64</code>, - <code class="filename">mips</code>, <code class="filename">powerpc</code>, and <code class="filename">arm</code>) - that you can use unaltered in the QEMU emulator. - These kernel images reside in the release - area - <a class="ulink" href="http://downloads.yoctoproject.org/releases/yocto/yocto-1.3/machines" target="_top">http://downloads.yoctoproject.org/releases/yocto/yocto-1.3/machines</a> - and are ideal for experimentation using Yocto Project. - For information on the image types you can build using the OpenEmbedded build system, - see the - "<a class="link" href="#ref-images" target="_top">Images</a>" chapter in - the Yocto Project Reference Manual. - </p><p> - If you plan on remotely deploying and debugging your application from within the - Eclipse IDE, you must have an image that contains the Yocto Target Communication - Framework (TCF) agent (<code class="filename">tcf-agent</code>). - By default, the Yocto Project provides only one type pre-built image that contains the - <code class="filename">tcf-agent</code>. - And, those images are SDK (e.g.<code class="filename">core-image-sato-sdk</code>). - </p><p> - If you want to use a different image type that contains the <code class="filename">tcf-agent</code>, - you can do so one of two ways: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>Modify the <code class="filename">conf/local.conf</code> configuration in - the <a class="link" href="#build-directory" target="_top">build directory</a> - and then rebuild the image. - With this method, you need to modify the - <a class="link" href="#var-EXTRA_IMAGE_FEATURES" target="_top"><code class="filename">EXTRA_IMAGE_FEATURES</code></a> - variable to have the value of "tools-debug" before rebuilding the image. - Once the image is rebuilt, the <code class="filename">tcf-agent</code> will be included - in the image and is launched automatically after the boot.</p></li><li class="listitem"><p>Manually build the <code class="filename">tcf-agent</code>. - To build the agent, follow these steps: - </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Be sure the ADT is installed as described in the - "<a class="link" href="#installing-the-adt" title="2.1. Installing the ADT and Toolchains">Installing the ADT and Toolchains</a>" section. - </p></li><li class="listitem"><p>Set up the cross-development environment as described in the - "<a class="link" href="#setting-up-the-cross-development-environment" title="2.2. Setting Up the Cross-Development Environment">Setting - Up the Cross-Development Environment</a>" section.</p></li><li class="listitem"><p>Get the <code class="filename">tcf-agent</code> source code using - the following commands: - </p><pre class="literallayout"> - $ git clone http://git.eclipse.org/gitroot/tcf/org.eclipse.tcf.agent.git - $ cd agent - </pre></li><li class="listitem"><p>Modify the <code class="filename">Makefile.inc</code> file - for the cross-compilation environment by setting the - <code class="filename">OPSYS</code> and - <a class="link" href="#var-MACHINE" target="_top"><code class="filename">MACHINE</code></a> - variables according to your target.</p></li><li class="listitem"><p>Use the cross-development tools to build the - <code class="filename">tcf-agent</code>. - Before you "Make" the file, be sure your cross-tools are set up first. - See the "<a class="link" href="#makefile-based-projects" title="4.2. Makefile-Based Projects">Makefile-Based Projects</a>" - section for information on how to make sure the cross-tools are set up - correctly.</p><p>If the build is successful, the <code class="filename">tcf-agent</code> output will - be <code class="filename">obj/$(OPSYS)/$(MACHINE)/Debug/agent</code>.</p></li><li class="listitem"><p>Deploy the agent into the image's root filesystem.</p></li></ol></div><p> - </p></li></ul></div><p> - </p></div><div class="section" title="2.3.2. Extracting the Root Filesystem"><div class="titlepage"><div><div><h3 class="title"><a id="extracting-the-root-filesystem"></a>2.3.2. Extracting the Root Filesystem</h3></div></div></div><p> - You must extract the root filesystem if you want to boot the image using NFS - or you want to use the root filesystem as the target sysroot. - For example, the Eclipse IDE environment with the Eclipse Yocto Plug-in installed allows you - to use QEMU to boot under NFS. - Another example is if you want to develop your target application using the - root filesystem as the target sysroot. - </p><p> - To extract the root filesystem, first <code class="filename">source</code> - the cross-development environment setup script and then - use the <code class="filename">runqemu-extract-sdk</code> command on the - filesystem image. - For example, the following commands set up the environment and then extract - the root filesystem from a previously built filesystem image tarball named - <code class="filename">core-image-sato-sdk-qemux86-2011091411831.rootfs.tar.bz2</code>. - The example extracts the root filesystem into the <code class="filename">$HOME/qemux86-sato</code> - directory: - </p><pre class="literallayout"> - $ source $HOME/poky/build/tmp/environment-setup-i586-poky-linux - $ runqemu-extract-sdk \ - tmp/deploy/images/core-image-sato-sdk-qemux86-2011091411831.rootfs.tar.bz2 \ - $HOME/qemux86-sato - </pre><p> - In this case, you could now point to the target sysroot at - <code class="filename">$HOME/qemux86-sato</code>. - </p></div></div></div> - - <div class="chapter" title="Chapter 3. Optionally Customizing the Development Packages Installation"><div class="titlepage"><div><div><h2 class="title"><a id="adt-package"></a>Chapter 3. Optionally Customizing the Development Packages Installation</h2></div></div></div><div class="toc"><dl><dt><span class="section"><a href="#package-management-systems">3.1. Package Management Systems</a></span></dt><dt><span class="section"><a href="#configuring-the-pms">3.2. Configuring the PMS</a></span></dt></dl></div><p> - Because the Yocto Project is suited for embedded Linux development, it is - likely that you will need to customize your development packages installation. - For example, if you are developing a minimal image, then you might not need - certain packages (e.g. graphics support packages). - Thus, you would like to be able to remove those packages from your target sysroot. - </p><div class="section" title="3.1. Package Management Systems"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="package-management-systems"></a>3.1. Package Management Systems</h2></div></div></div><p> - The OpenEmbedded build system supports the generation of sysroot files using - three different Package Management Systems (PMS): - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><span class="emphasis"><em>OPKG:</em></span> A less well known PMS whose use - originated in the OpenEmbedded and OpenWrt embedded Linux projects. - This PMS works with files packaged in an <code class="filename">.ipk</code> format. - See <a class="ulink" href="http://en.wikipedia.org/wiki/Opkg" target="_top">http://en.wikipedia.org/wiki/Opkg</a> for more - information about OPKG.</p></li><li class="listitem"><p><span class="emphasis"><em>RPM:</em></span> A more widely known PMS intended for GNU/Linux - distributions. - This PMS works with files packaged in an <code class="filename">.rms</code> format. - The build system currently installs through this PMS by default. - See <a class="ulink" href="http://en.wikipedia.org/wiki/RPM_Package_Manager" target="_top">http://en.wikipedia.org/wiki/RPM_Package_Manager</a> - for more information about RPM.</p></li><li class="listitem"><p><span class="emphasis"><em>Debian:</em></span> The PMS for Debian-based systems - is built on many PMS tools. - The lower-level PMS tool <code class="filename">dpkg</code> forms the base of the Debian PMS. - For information on dpkg see - <a class="ulink" href="http://en.wikipedia.org/wiki/Dpkg" target="_top">http://en.wikipedia.org/wiki/Dpkg</a>.</p></li></ul></div><p> - </p></div><div class="section" title="3.2. Configuring the PMS"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="configuring-the-pms"></a>3.2. Configuring the PMS</h2></div></div></div><p> - Whichever PMS you are using, you need to be sure that the - <a class="link" href="#var-PACKAGE_CLASSES" target="_top"><code class="filename">PACKAGE_CLASSES</code></a> - variable in the <code class="filename">conf/local.conf</code> - file is set to reflect that system. - The first value you choose for the variable specifies the package file format for the root - filesystem at sysroot. - Additional values specify additional formats for convenience or testing. - See the configuration file for details. - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3> - For build performance information related to the PMS, see - <a class="link" href="#ref-classes-package" target="_top">Packaging - <code class="filename">package*.bbclass</code></a> - in the Yocto Project Reference Manual. - </div><p> - As an example, consider a scenario where you are using OPKG and you want to add - the <code class="filename">libglade</code> package to the target sysroot. - </p><p> - First, you should generate the <code class="filename">ipk</code> file for the - <code class="filename">libglade</code> package and add it - into a working <code class="filename">opkg</code> repository. - Use these commands: - </p><pre class="literallayout"> - $ bitbake libglade - $ bitbake package-index - </pre><p> - </p><p> - Next, source the environment setup script found in the - <a class="link" href="#source-directory" target="_top">source directory</a>. - Follow that by setting up the installation destination to point to your - sysroot as <code class="filename"><sysroot_dir></code>. - Finally, have an OPKG configuration file <code class="filename"><conf_file></code> - that corresponds to the <code class="filename">opkg</code> repository you have just created. - The following command forms should now work: - </p><pre class="literallayout"> - $ opkg-cl –f <conf_file> -o <sysroot_dir> update - $ opkg-cl –f <cconf_file> -o <sysroot_dir> \ - --force-overwrite install libglade - $ opkg-cl –f <cconf_file> -o <sysroot_dir> \ - --force-overwrite install libglade-dbg - $ opkg-cl –f <conf_file> -o <sysroot_dir> \ - --force-overwrite install libglade-dev - </pre><p> - </p></div></div> - - <div class="chapter" title="Chapter 4. Using the Command Line"><div class="titlepage"><div><div><h2 class="title"><a id="using-the-command-line"></a>Chapter 4. Using the Command Line</h2></div></div></div><div class="toc"><dl><dt><span class="section"><a href="#autotools-based-projects">4.1. Autotools-Based Projects</a></span></dt><dt><span class="section"><a href="#makefile-based-projects">4.2. Makefile-Based Projects</a></span></dt></dl></div><p> - Recall that earlier the manual discussed how to use an existing toolchain - tarball that had been installed into <code class="filename">/opt/poky</code>, - which is outside of the build directory - (see the section "<a class="link" href="#using-an-existing-toolchain-tarball" title="2.1.2. Using a Cross-Toolchain Tarball">Using an Existing - Toolchain Tarball)</a>". - And, that sourcing your architecture-specific environment setup script - initializes a suitable cross-toolchain development environment. - During the setup, locations for the compiler, QEMU scripts, QEMU binary, - a special version of <code class="filename">pkgconfig</code> and other useful - utilities are added to the <code class="filename">PATH</code> variable. - Variables to assist <code class="filename">pkgconfig</code> and <code class="filename">autotools</code> - are also defined so that, - for example, <code class="filename">configure.sh</code> can find pre-generated - test results for tests that need target hardware on which to run. - These conditions allow you to easily use the toolchain outside of the - OpenEmbedded build environment on both autotools-based projects and - Makefile-based projects. - </p><div class="section" title="4.1. Autotools-Based Projects"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="autotools-based-projects"></a>4.1. Autotools-Based Projects</h2></div></div></div><p> - For an Autotools-based project, you can use the cross-toolchain by just - passing the appropriate host option to <code class="filename">configure.sh</code>. - The host option you use is derived from the name of the environment setup - script in <code class="filename">/opt/poky</code> resulting from unpacking the - cross-toolchain tarball. - For example, the host option for an ARM-based target that uses the GNU EABI - is <code class="filename">armv5te-poky-linux-gnueabi</code>. - Note that the name of the script is - <code class="filename">environment-setup-armv5te-poky-linux-gnueabi</code>. - Thus, the following command works: - </p><pre class="literallayout"> - $ configure --host=armv5te-poky-linux-gnueabi \ - --with-libtool-sysroot=<sysroot-dir> - </pre><p> - </p><p> - This single command updates your project and rebuilds it using the appropriate - cross-toolchain tools. - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3> - If <code class="filename">configure</code> script results in problems recognizing the - <code class="filename">--with-libtool-sysroot=<sysroot-dir></code> option, - regenerate the script to enable the support by doing the following and then - re-running the script: - <pre class="literallayout"> - $ libtoolize --automake - $ aclocal -I ${OECORE_NATIVE_SYSROOT}/usr/share/aclocal \ - [-I <dir_containing_your_project-specific_m4_macros>] - $ autoconf - $ autoheader - $ automake -a - </pre></div></div><div class="section" title="4.2. Makefile-Based Projects"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="makefile-based-projects"></a>4.2. Makefile-Based Projects</h2></div></div></div><p> - For a Makefile-based project, you use the cross-toolchain by making sure - the tools are used. - You can do this as follows: - </p><pre class="literallayout"> - CC=arm-poky-linux-gnueabi-gcc - LD=arm-poky-linux-gnueabi-ld - CFLAGS=”${CFLAGS} --sysroot=<sysroot-dir>” - CXXFLAGS=”${CXXFLAGS} --sysroot=<sysroot-dir>” - </pre><p> - </p></div></div> - - - -</div> - -<table border="0" summary="manufactured viewport for HTML img" cellspacing="0" cellpadding="0" width="100%"><tr><td align="left"><img src="figures/bsp-title.png" align="left" width="100%" /></td></tr></table> - - <div xml:lang="en" class="book" lang="en"><div class="titlepage"><div><div><h1 class="title"><a id="bsp-guide"></a></h1></div><div><div class="authorgroup"> - <div class="author"><h3 class="author"><span class="firstname">Tom</span> <span class="surname">Zanussi</span></h3><div class="affiliation"> - <span class="orgname">Intel Corporation<br /></span> - </div><code class="email"><<a class="email" href="mailto:tom.zanussi@intel.com">tom.zanussi@intel.com</a>></code></div> - <div class="author"><h3 class="author"><span class="firstname">Richard</span> <span class="surname">Purdie</span></h3><div class="affiliation"> - <span class="orgname">Linux Foundation<br /></span> - </div><code class="email"><<a class="email" href="mailto:richard.purdie@linuxfoundation.org">richard.purdie@linuxfoundation.org</a>></code></div> - </div></div><div><p class="copyright">Copyright © 2010-2012 Linux Foundation</p></div><div><div class="legalnotice" title="Legal Notice"><a id="id1501714"></a> - <p> - Permission is granted to copy, distribute and/or modify this document under - the terms of the <a class="ulink" href="http://creativecommons.org/licenses/by-nc-sa/2.0/uk/" target="_top">Creative Commons Attribution-Non-Commercial-Share Alike 2.0 UK: England & Wales</a> as published by Creative Commons. - </p> - <div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3> - Due to production processes, there could be differences between the Yocto Project - documentation bundled in the release tarball and the - Yocto Project Board Support Package (BSP) Developer's Guide on - the <a class="ulink" href="http://www.yoctoproject.org" target="_top">Yocto Project</a> website. - For the latest version of this manual, see the manual on the website. - </div> - </div></div><div><div class="revhistory"><table border="1" width="100%" summary="Revision history"><tr><th align="left" valign="top" colspan="2"><b>Revision History</b></th></tr> - <tr><td align="left">Revision 0.9</td><td align="left">24 November 2010</td></tr><tr><td align="left" colspan="2">The initial document draft released with the Yocto Project 0.9 Release.</td></tr> - <tr><td align="left">Revision 1.0</td><td align="left">6 April 2011</td></tr><tr><td align="left" colspan="2">Released with the Yocto Project 1.0 Release.</td></tr> - <tr><td align="left">Revision 1.0.1</td><td align="left">23 May 2011</td></tr><tr><td align="left" colspan="2">Released with the Yocto Project 1.0.1 Release.</td></tr> - <tr><td align="left">Revision 1.1</td><td align="left">6 October 2011</td></tr><tr><td align="left" colspan="2">Released with the Yocto Project 1.1 Release.</td></tr> - <tr><td align="left">Revision 1.2</td><td align="left">April 2012</td></tr><tr><td align="left" colspan="2">Released with the Yocto Project 1.2 Release.</td></tr> - <tr><td align="left">Revision 1.3</td><td align="left">Sometime in 2012</td></tr><tr><td align="left" colspan="2">Released with the Yocto Project 1.3 Release.</td></tr> - </table></div></div></div><hr /></div> - - - <div class="chapter" title="Chapter 1. Board Support Packages (BSP) - Developer's Guide"><div class="titlepage"><div><div><h2 class="title"><a id="bsp"></a>Chapter 1. Board Support Packages (BSP) - Developer's Guide</h2></div></div></div><div class="toc"><dl><dt><span class="section"><a href="#bsp-layers">1.1. BSP Layers</a></span></dt><dt><span class="section"><a href="#bsp-filelayout">1.2. Example Filesystem Layout</a></span></dt><dd><dl><dt><span class="section"><a href="#bsp-filelayout-license">1.2.1. License Files</a></span></dt><dt><span class="section"><a href="#bsp-filelayout-readme">1.2.2. README File</a></span></dt><dt><span class="section"><a href="#bsp-filelayout-readme-sources">1.2.3. README.sources File</a></span></dt><dt><span class="section"><a href="#bsp-filelayout-binary">1.2.4. Pre-built User Binaries</a></span></dt><dt><span class="section"><a href="#bsp-filelayout-layer">1.2.5. Layer Configuration File</a></span></dt><dt><span class="section"><a href="#bsp-filelayout-machine">1.2.6. Hardware Configuration Options</a></span></dt><dt><span class="section"><a href="#bsp-filelayout-misc-recipes">1.2.7. Miscellaneous Recipe Files</a></span></dt><dt><span class="section"><a href="#bsp-filelayout-core-recipes">1.2.8. Core Recipe Files</a></span></dt><dt><span class="section"><a href="#bsp-filelayout-recipes-graphics">1.2.9. Display Support Files</a></span></dt><dt><span class="section"><a href="#bsp-filelayout-kernel">1.2.10. Linux Kernel Configuration</a></span></dt></dl></dd><dt><span class="section"><a href="#requirements-and-recommendations-for-released-bsps">1.3. Requirements and Recommendations for Released BSPs</a></span></dt><dd><dl><dt><span class="section"><a href="#released-bsp-requirements">1.3.1. Released BSP Requirements</a></span></dt><dt><span class="section"><a href="#released-bsp-recommendations">1.3.2. Released BSP Recommendations</a></span></dt></dl></dd><dt><span class="section"><a href="#customizing-a-recipe-for-a-bsp">1.4. Customizing a Recipe for a BSP</a></span></dt><dt><span class="section"><a href="#bsp-licensing-considerations">1.5. BSP Licensing Considerations</a></span></dt><dt><span class="section"><a href="#using-the-yocto-projects-bsp-tools">1.6. Using the Yocto Project's BSP Tools</a></span></dt><dd><dl><dt><span class="section"><a href="#common-features">1.6.1. Common Features</a></span></dt><dt><span class="section"><a href="#creating-a-new-bsp-layer-using-the-yocto-bsp-script">1.6.2. Creating a new BSP Layer Using the yocto-bsp Script</a></span></dt><dt><span class="section"><a href="#managing-kernel-patches-and-config-items-with-yocto-kernel">1.6.3. Managing Kernel Patches and Config Items with yocto-kernel</a></span></dt></dl></dd></dl></div><p> - A Board Support Package (BSP) is a collection of information that - defines how to support a particular hardware device, set of devices, or - hardware platform. - The BSP includes information about the hardware features - present on the device and kernel configuration information along with any - additional hardware drivers required. - The BSP also lists any additional software - components required in addition to a generic Linux software stack for both - essential and optional platform features. - </p><p> - This chapter (or document if you are reading the BSP Developer's Guide) - talks about BSP Layers, defines a structure for components - so that BSPs follow a commonly understood layout, discusses how to customize - a recipe for a BSP, addresses BSP licensing, and provides information that - shows you how to create and manage a - <a class="link" href="#bsp-layers" title="1.1. BSP Layers">BSP Layer</a> using two Yocto Project - <a class="link" href="#using-the-yocto-projects-bsp-tools" title="1.6. Using the Yocto Project's BSP Tools">BSP Tools</a>. - </p><div class="section" title="1.1. BSP Layers"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="bsp-layers"></a>1.1. BSP Layers</h2></div></div></div><p> - The BSP consists of a file structure inside a base directory. - Collectively, you can think of the base directory and the file structure - as a BSP Layer. - BSP Layers use the following naming convention: - </p><pre class="literallayout"> - meta-<bsp_name> - </pre><p> - "bsp_name" is a placeholder for the machine or platform name. - </p><p> - The layer's base directory (<code class="filename">meta-<bsp_name></code>) is the root - of the BSP Layer. - This root is what you add to the - <a class="link" href="#var-BBLAYERS" target="_top"><code class="filename">BBLAYERS</code></a> - variable in the <code class="filename">conf/bblayers.conf</code> file found in the - <a class="link" href="#build-directory" target="_top">build directory</a>. - Adding the root allows the OpenEmbedded build system to recognize the BSP - definition and from it build an image. - Here is an example: - </p><pre class="literallayout"> - BBLAYERS = " \ - /usr/local/src/yocto/meta \ - /usr/local/src/yocto/meta-yocto \ - /usr/local/src/yocto/meta-<bsp_name> \ - " - </pre><p> - </p><p> - Some BSPs require additional layers on - top of the BSP's root layer in order to be functional. - For these cases, you also need to add those layers to the - <code class="filename">BBLAYERS</code> variable in order to build the BSP. - You must also specify in the "Dependencies" section of the BSP's - <code class="filename">README</code> file any requirements for additional - layers and, preferably, any - build instructions that might be contained elsewhere - in the <code class="filename">README</code> file. - </p><p> - Some layers function as a layer to hold other BSP layers. - An example of this type of layer is the <code class="filename">meta-intel</code> layer. - The <code class="filename">meta-intel</code> layer contains over 10 individual BSP layers. - </p><p> - For more detailed information on layers, see the - "<a class="link" href="#understanding-and-creating-layers" target="_top">Understanding and Creating Layers</a>" - section of the Yocto Project Development Manual. - You can also see the detailed examples in the appendices of the - Yocto Project Development Manual. - </p></div><div class="section" title="1.2. Example Filesystem Layout"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="bsp-filelayout"></a>1.2. Example Filesystem Layout</h2></div></div></div><p> - Providing a common form allows end-users to understand and become familiar - with the layout. - A common format also encourages standardization of software support of hardware. - </p><p> - The proposed form does have elements that are specific to the - OpenEmbedded build system. - It is intended that this information can be - used by other build systems besides the OpenEmbedded build system - and that it will be simple - to extract information and convert it to other formats if required. - The OpenEmbedded build system, through its standard layers mechanism, can directly - accept the format described as a layer. - The BSP captures all - the hardware-specific details in one place in a standard format, which is - useful for any person wishing to use the hardware platform regardless of - the build system they are using. - </p><p> - The BSP specification does not include a build system or other tools - - it is concerned with the hardware-specific components only. - At the end-distribution point, you can ship the BSP combined with a build system - and other tools. - However, it is important to maintain the distinction that these - are separate components that happen to be combined in certain end products. - </p><p> - Before looking at the common form for the file structure inside a BSP Layer, - you should be aware that some requirements do exist in order for a BSP to - be considered compliant with the Yocto Project. - For that list of requirements, see the - "<a class="link" href="#released-bsp-requirements" title="1.3.1. Released BSP Requirements">Released BSP Requirements</a>" - section. - </p><p> - Below is the common form for the file structure inside a BSP Layer. - While you can use this basic form for the standard, realize that the actual structures - for specific BSPs could differ. - - </p><pre class="literallayout"> - meta-<bsp_name>/ - meta-<bsp_name>/<bsp_license_file> - meta-<bsp_name>/README - meta-<bsp_name>/README.sources - meta-<bsp_name>/binary/<bootable_images> - meta-<bsp_name>/conf/layer.conf - meta-<bsp_name>/conf/machine/*.conf - meta-<bsp_name>/recipes-bsp/* - meta-<bsp_name>/recipes-core/* - meta-<bsp_name>/recipes-graphics/* - meta-<bsp_name>/recipes-kernel/linux/linux-yocto_<kernel_rev>.bbappend - </pre><p> - </p><p> - Below is an example of the Crown Bay BSP: - - </p><pre class="literallayout"> - meta-crownbay/COPYING.MIT - meta-crownbay/README - meta-crownbay/README.sources - meta-crownbay/binary/ - meta-crownbay/conf/ - meta-crownbay/conf/layer.conf - meta-crownbay/conf/machine/ - meta-crownbay/conf/machine/crownbay.conf - meta-crownbay/conf/machine/crownbay-noemgd.conf - meta-crownbay/recipes-bsp/ - meta-crownbay/recipes-bsp/formfactor/ - meta-crownbay/recipes-bsp/formfactor/formfactor_0.0.bbappend - meta-crownbay/recipes-bsp/formfactor/formfactor/ - meta-crownbay/recipes-bsp/formfactor/formfactor/crownbay/ - meta-crownbay/recipes-bsp/formfactor/formfactor/crownbay/machconfig - meta-crownbay/recipes-bsp/formfactor/formfactor/crownbay-noemgd/ - meta-crownbay/recipes-bsp/formfactor/formfactor/crownbay-noemgd/machconfig - meta-crownbay/recipes-core/ - meta-crownbay/recipes-core/tasks/ - meta-crownbay/recipes-core/tasks/task-core-tools-profile.bbappend - meta-crownbay/recipes-graphics/ - meta-crownbay/recipes-graphics/xorg-xserver/ - meta-crownbay/recipes-graphics/xorg-xserver/xserver-xf86-config_0.1.bbappend - meta-crownbay/recipes-graphics/xorg-xserver/xserver-xf86-config/ - meta-crownbay/recipes-graphics/xorg-xserver/xserver-xf86-config/crownbay/ - meta-crownbay/recipes-graphics/xorg-xserver/xserver-xf86-config/crownbay/xorg.conf - meta-crownbay/recipes-graphics/xorg-xserver/xserver-xf86-config/crownbay-noemgd/ - meta-crownbay/recipes-graphics/xorg-xserver/xserver-xf86-config/crownbay-noemgd/xorg.conf - meta-crownbay/recipes-kernel/ - meta-crownbay/recipes-kernel/linux/ - meta-crownbay/recipes-kernel/linux/linux-yocto-rt_3.0.bbappend - meta-crownbay/recipes-kernel/linux/linux-yocto_2.6.37.bbappend - meta-crownbay/recipes-kernel/linux/linux-yocto_3.0.bbappend - </pre><p> - </p><p> - The following sections describe each part of the proposed BSP format. - </p><div class="section" title="1.2.1. License Files"><div class="titlepage"><div><div><h3 class="title"><a id="bsp-filelayout-license"></a>1.2.1. License Files</h3></div></div></div><p> - You can find these files in the BSP Layer at: - </p><pre class="literallayout"> - meta-<bsp_name>/<bsp_license_file> - </pre><p> - </p><p> - These optional files satisfy licensing requirements for the BSP. - The type or types of files here can vary depending on the licensing requirements. - For example, in the Crown Bay BSP all licensing requirements are handled with the - <code class="filename">COPYING.MIT</code> file. - </p><p> - Licensing files can be MIT, BSD, GPLv*, and so forth. - These files are recommended for the BSP but are optional and totally up to the BSP developer. - </p></div><div class="section" title="1.2.2. README File"><div class="titlepage"><div><div><h3 class="title"><a id="bsp-filelayout-readme"></a>1.2.2. README File</h3></div></div></div><p> - You can find this file in the BSP Layer at: - </p><pre class="literallayout"> - meta-<bsp_name>/README - </pre><p> - </p><p> - This file provides information on how to boot the live images that are optionally - included in the <code class="filename">binary/</code> directory. - The <code class="filename">README</code> file also provides special information needed for - building the image. - </p><p> - At a minimum, the <code class="filename">README</code> file must - contain a list of dependencies, such as the names of - any other layers on which the BSP depends and the name of - the BSP maintainer with his or her contact information. - </p></div><div class="section" title="1.2.3. README.sources File"><div class="titlepage"><div><div><h3 class="title"><a id="bsp-filelayout-readme-sources"></a>1.2.3. README.sources File</h3></div></div></div><p> - You can find this file in the BSP Layer at: - </p><pre class="literallayout"> - meta-<bsp_name>/README.sources - </pre><p> - </p><p> - This file provides information on where to locate the BSP source files. - For example, information provides where to find the sources that comprise - the images shipped with the BSP. - Information is also included to help you find the metadata used to generate the images - that ship with the BSP. - </p></div><div class="section" title="1.2.4. Pre-built User Binaries"><div class="titlepage"><div><div><h3 class="title"><a id="bsp-filelayout-binary"></a>1.2.4. Pre-built User Binaries</h3></div></div></div><p> - You can find these files in the BSP Layer at: - </p><pre class="literallayout"> - meta-<bsp_name>/binary/<bootable_images> - </pre><p> - </p><p> - This optional area contains useful pre-built kernels and user-space filesystem - images appropriate to the target system. - This directory typically contains graphical (e.g. sato) and minimal live images - when the BSP tarball has been created and made available in the - <a class="ulink" href="http://www.yoctoproject.org" target="_top">Yocto Project</a> website. - You can use these kernels and images to get a system running and quickly get started - on development tasks. - </p><p> - The exact types of binaries present are highly hardware-dependent. - However, a README file should be present in the BSP Layer that explains how to use - the kernels and images with the target hardware. - If pre-built binaries are present, source code to meet licensing requirements must also - exist in some form. - </p></div><div class="section" title="1.2.5. Layer Configuration File"><div class="titlepage"><div><div><h3 class="title"><a id="bsp-filelayout-layer"></a>1.2.5. Layer Configuration File</h3></div></div></div><p> - You can find this file in the BSP Layer at: - </p><pre class="literallayout"> - meta-<bsp_name>/conf/layer.conf - </pre><p> - </p><p> - The <code class="filename">conf/layer.conf</code> file identifies the file structure as a - layer, identifies the - contents of the layer, and contains information about how the build - system should use it. - Generally, a standard boilerplate file such as the following works. - In the following example, you would replace "<code class="filename">bsp</code>" and - "<code class="filename">_bsp</code>" with the actual name - of the BSP (i.e. <code class="filename"><bsp_name></code> from the example template). - </p><p> - </p><pre class="literallayout"> - # We have a conf and classes directory, add to BBPATH - BBPATH := "${BBPATH}:${LAYERDIR}" - - # We have a recipes directory, add to BBFILES - BBFILES := "${BBFILES} ${LAYERDIR}/recipes-*/*.bb \ - ${LAYERDIR}/recipes-*/*.bbappend" - - BBFILE_COLLECTIONS += "bsp" - BBFILE_PATTERN_bsp := "^${LAYERDIR}/" - BBFILE_PRIORITY_bsp = "6" - </pre><p> - </p><p> - To illustrate the string substitutions, here are the last three statements from the Crown - Bay <code class="filename">conf/layer.conf</code> file: - </p><pre class="literallayout"> - BBFILE_COLLECTIONS += "crownbay" - BBFILE_PATTERN_crownbay := "^${LAYERDIR}/" - BBFILE_PRIORITY_crownbay = "6" - </pre><p> - </p><p> - This file simply makes BitBake aware of the recipes and configuration directories. - The file must exist so that the OpenEmbedded build system can recognize the BSP. - </p></div><div class="section" title="1.2.6. Hardware Configuration Options"><div class="titlepage"><div><div><h3 class="title"><a id="bsp-filelayout-machine"></a>1.2.6. Hardware Configuration Options</h3></div></div></div><p> - You can find these files in the BSP Layer at: - </p><pre class="literallayout"> - meta-<bsp_name>/conf/machine/*.conf - </pre><p> - </p><p> - The machine files bind together all the information contained elsewhere - in the BSP into a format that the build system can understand. - If the BSP supports multiple machines, multiple machine configuration files - can be present. - These filenames correspond to the values to which users have set the - <a class="link" href="#var-MACHINE" target="_top"><code class="filename">MACHINE</code></a> variable. - </p><p> - These files define things such as the kernel package to use - (<a class="link" href="#var-PREFERRED_PROVIDER" target="_top"><code class="filename">PREFERRED_PROVIDER</code></a> - of virtual/kernel), the hardware drivers to - include in different types of images, any special software components - that are needed, any bootloader information, and also any special image - format requirements. - </p><p> - Each BSP Layer requires at least one machine file. - However, you can supply more than one file. - For example, in the Crown Bay BSP shown earlier in this section, the - <code class="filename">conf/machine</code> directory contains two configuration files: - <code class="filename">crownbay.conf</code> and <code class="filename">crownbay-noemgd.conf</code>. - The <code class="filename">crownbay.conf</code> file is used for the Crown Bay BSP - that supports the <span class="trademark">Intel</span>® Embedded - Media and Graphics Driver (<span class="trademark">Intel</span>® - EMGD), while the <code class="filename">crownbay-noemgd.conf</code> file is used for the - Crown Bay BSP that does not support the <span class="trademark">Intel</span>® - EMGD. - </p><p> - This <code class="filename">crownbay.conf</code> file could also include - a hardware "tuning" file that is commonly used to - define the package architecture and specify - optimization flags, which are carefully chosen to give best - performance on a given processor. - </p><p> - Tuning files are found in the <code class="filename">meta/conf/machine/include</code> - directory within the - <a class="link" href="#source-directory" target="_top">source directory</a>. - Tuning files can also reside in the BSP Layer itself. - For example, the <code class="filename">ia32-base.inc</code> file resides in the - <code class="filename">meta-intel</code> BSP Layer in <code class="filename">conf/machine/include</code>. - </p><p> - To use an include file, you simply include them in the machine configuration file. - For example, the Crown Bay BSP <code class="filename">crownbay.conf</code> has the - following statements: - </p><pre class="literallayout"> - include conf/machine/include/tune-atom.inc - include conf/machine/include/ia32-base.inc - </pre><p> - </p></div><div class="section" title="1.2.7. Miscellaneous Recipe Files"><div class="titlepage"><div><div><h3 class="title"><a id="bsp-filelayout-misc-recipes"></a>1.2.7. Miscellaneous Recipe Files</h3></div></div></div><p> - You can find these files in the BSP Layer at: - </p><pre class="literallayout"> - meta-<bsp_name>/recipes-bsp/* - </pre><p> - </p><p> - This optional directory contains miscellaneous recipe files for the BSP. - Most notably would be the formfactor files. - For example, in the Crown Bay BSP there is the - <code class="filename">formfactor_0.0.bbappend</code> file, which is an append file used - to augment the recipe that starts the build. - Furthermore, there are machine-specific settings used during the build that are - defined by the <code class="filename">machconfig</code> files. - In the Crown Bay example, two <code class="filename">machconfig</code> files exist: - one that supports the - <span class="trademark">Intel</span>® Embedded - Media and Graphics Driver (<span class="trademark">Intel</span>® - EMGD) and one that does not: - </p><pre class="literallayout"> - meta-crownbay/recipes-bsp/formfactor/formfactor/crownbay/machconfig - meta-crownbay/recipes-bsp/formfactor/formfactor/crownbay-noemgd/machconfig - meta-crownbay/recipes-bsp/formfactor/formfactor_0.0.bbappend - </pre><p> - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p> - If a BSP does not have a formfactor entry, defaults are established according to - the formfactor configuration file that is installed by the main - formfactor recipe - <code class="filename">meta/recipes-bsp/formfactor/formfactor_0.0.bb</code>, - which is found in the - <a class="link" href="#source-directory" target="_top">source directory</a>. - </p></div></div><div class="section" title="1.2.8. Core Recipe Files"><div class="titlepage"><div><div><h3 class="title"><a id="bsp-filelayout-core-recipes"></a>1.2.8. Core Recipe Files</h3></div></div></div><p> - You can find these files in the BSP Layer at: - </p><pre class="literallayout"> - meta-<bsp_name>/recipes-core/* - </pre><p> - </p><p> - This directory contains recipe files that are almost always necessary to build a - useful, working Linux image. - Thus, the term "core" is used to group these recipes. - For example, in the Crown Bay BSP there is the - <code class="filename">task-core-tools-profile.bbappend</code> file, which is an append file used - to recommend that the - <a class="ulink" href="http://sourceware.org/systemtap/wiki" target="_top">SystemTap</a> - package be included as a package when the image is built. - </p></div><div class="section" title="1.2.9. Display Support Files"><div class="titlepage"><div><div><h3 class="title"><a id="bsp-filelayout-recipes-graphics"></a>1.2.9. Display Support Files</h3></div></div></div><p> - You can find these files in the BSP Layer at: - </p><pre class="literallayout"> - meta-<bsp_name>/recipes-graphics/* - </pre><p> - </p><p> - This optional directory contains recipes for the BSP if it has - special requirements for graphics support. - All files that are needed for the BSP to support a display are kept here. - For example, the Crown Bay BSP contains two versions of the - <code class="filename">xorg.conf</code> file. - The version in <code class="filename">crownbay</code> builds a BSP that supports the - <span class="trademark">Intel</span>® Embedded Media Graphics Driver (EMGD), - while the version in <code class="filename">crownbay-noemgd</code> builds - a BSP that supports Video Electronics Standards Association (VESA) graphics only: - </p><pre class="literallayout"> - meta-crownbay/recipes-graphics/xorg-xserver/xserver-xf86-config_0.1.bbappend - meta-crownbay/recipes-graphics/xorg-xserver/xserver-xf86-config/crownbay/xorg.conf - meta-crownbay/recipes-graphics/xorg-xserver/xserver-xf86-config/crownbay-noemgd/xorg.conf - </pre><p> - </p></div><div class="section" title="1.2.10. Linux Kernel Configuration"><div class="titlepage"><div><div><h3 class="title"><a id="bsp-filelayout-kernel"></a>1.2.10. Linux Kernel Configuration</h3></div></div></div><p> - You can find these files in the BSP Layer at: - </p><pre class="literallayout"> - meta-<bsp_name>/recipes-kernel/linux/linux-yocto_*.bbappend - </pre><p> - </p><p> - These files append your specific changes to the main kernel recipe you are using. - </p><p> - For your BSP, you typically want to use an existing Yocto Project kernel recipe found in the - <a class="link" href="#source-directory" target="_top">source directory</a> - at <code class="filename">meta/recipes-kernel/linux</code>. - You can append your specific changes to the kernel recipe by using a - similarly named append file, which is located in the BSP Layer (e.g. - the <code class="filename">meta-<bsp_name>/recipes-kernel/linux</code> directory). - </p><p> - Suppose you are using the <code class="filename">linux-yocto_3.4.bb</code> recipe to build - the kernel. - In other words, you have selected the kernel in your - <code class="filename"><bsp_name>.conf</code> file by adding the following statements: - </p><pre class="literallayout"> - PREFERRED_PROVIDER_virtual/kernel ?= "linux-yocto" - PREFERRED_VERSION_linux-yocto = "3.4%" - </pre><p> - You would use the <code class="filename">linux-yocto_3.4.bbappend</code> file to append - specific BSP settings to the kernel, thus configuring the kernel for your particular BSP. - </p><p> - As an example, look at the existing Crown Bay BSP. - The append file used is: - </p><pre class="literallayout"> - meta-crownbay/recipes-kernel/linux/linux-yocto_3.4.bbappend - </pre><p> - The following listing shows the file. - Be aware that the actual commit ID strings in this example listing might be different - than the actual strings in the file from the <code class="filename">meta-intel</code> - Git source repository. - </p><pre class="literallayout"> - FILESEXTRAPATHS_prepend := "${THISDIR}/${PN}:" - - COMPATIBLE_MACHINE_crownbay = "crownbay" - KMACHINE_crownbay = "crownbay" - KBRANCH_crownbay = "standard/default/crownbay" - - COMPATIBLE_MACHINE_crownbay-noemgd = "crownbay-noemgd" - KMACHINE_crownbay-noemgd = "crownbay" - KBRANCH_crownbay-noemgd = "standard/default/crownbay" - - SRCREV_machine_pn-linux-yocto_crownbay ?= "48101e609711fcfe8d5e737a37a5a69f4bd57d9a" - SRCREV_meta_pn-linux-yocto_crownbay ?= "5b4c9dc78b5ae607173cc3ddab9bce1b5f78129b" - - SRCREV_machine_pn-linux-yocto_crownbay-noemgd ?= "48101e609711fcfe8d5e737a37a5a69f4bd57d9a" - SRCREV_meta_pn-linux-yocto_crownbay-noemgd ?= "5b4c9dc78b5ae607173cc3ddab9bce1b5f78129b" - </pre><p> - This append file contains statements used to support the Crown Bay BSP for both - <span class="trademark">Intel</span>® EMGD and the VESA graphics. - The build process, in this case, recognizes and uses only the statements that - apply to the defined machine name - <code class="filename">crownbay</code> in this case. - So, the applicable statements in the <code class="filename">linux-yocto_3.4.bbappend</code> - file are follows: - </p><pre class="literallayout"> - FILESEXTRAPATHS_prepend := "${THISDIR}/${PN}:" - - COMPATIBLE_MACHINE_crownbay = "crownbay" - KMACHINE_crownbay = "crownbay" - KBRANCH_crownbay = "standard/default/crownbay" - - SRCREV_machine_pn-linux-yocto_crownbay ?= "48101e609711fcfe8d5e737a37a5a69f4bd57d9a" - SRCREV_meta_pn-linux-yocto_crownbay ?= "5b4c9dc78b5ae607173cc3ddab9bce1b5f78129b" - </pre><p> - The append file defines <code class="filename">crownbay</code> as the - <a class="link" href="#var-COMPATIBLE_MACHINE" target="_top"><code class="filename">COMPATIBLE_MACHINE</code></a> - and uses the - <a class="link" href="#var-KMACHINE" target="_top"><code class="filename">KMACHINE</code></a> variable to - ensure the machine name used by the OpenEmbedded build system maps to the - machine name used by the Linux Yocto kernel. - The file also uses the optional - <a class="link" href="#var-KBRANCH" target="_top"><code class="filename">KBRANCH</code></a> variable - to ensure the build process uses the <code class="filename">standard/default/crownbay</code> - kernel branch. - Finally, the append file points to the specific top commits in the - <a class="link" href="#source-directory" target="_top">source directory</a> Git - repository and the <code class="filename">meta</code> Git repository branches to identify the - exact kernel needed to build the Crown Bay BSP. - </p><p> - One thing missing in this particular BSP, which you will typically need when - developing a BSP, is the kernel configuration file (<code class="filename">.config</code>) for your BSP. - When developing a BSP, you probably have a kernel configuration file or a set of kernel - configuration files that, when taken together, define the kernel configuration for your BSP. - You can accomplish this definition by putting the configurations in a file or a set of files - inside a directory located at the same level as your kernel's append file and having the same - name as the kernel's main recipe file. - With all these conditions met, simply reference those files in a - <code class="filename">SRC_URI</code> statement in the append file. - </p><p> - For example, suppose you had a some configuration options in a file called - <code class="filename">network_configs.cfg</code>. - You can place that file inside a directory named <code class="filename">/linux-yocto</code> and then add - a <code class="filename">SRC_URI</code> statement such as the following to the append file. - When the OpenEmbedded build system builds the kernel, the configuration options are - picked up and applied. - </p><pre class="literallayout"> - SRC_URI += "file://network_configs.cfg" - </pre><p> - </p><p> - To group related configurations into multiple files, you perform a similar procedure. - Here is an example that groups separate configurations specifically for Ethernet and graphics - into their own files and adds the configurations - by using a <code class="filename">SRC_URI</code> statement like the following in your append file: - </p><pre class="literallayout"> - SRC_URI += "file://myconfig.cfg \ - file://eth.cfg \ - file://gfx.cfg" - </pre><p> - </p><p> - The <code class="filename">FILESEXTRAPATHS</code> variable is in boilerplate form in the - previous example in order to make it easy to do that. - This variable must be in your layer or BitBake will not find the patches or - configurations even if you have them in your <code class="filename">SRC_URI</code>. - The <code class="filename">FILESEXTRAPATHS</code> variable enables the build process to - find those configuration files. - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p> - Other methods exist to accomplish grouping and defining configuration options. - For example, if you are working with a local clone of the kernel repository, - you could checkout the kernel's <code class="filename">meta</code> branch, make your changes, - and then push the changes to the local bare clone of the kernel. - The result is that you directly add configuration options to the - <code class="filename">meta</code> branch for your BSP. - The configuration options will likely end up in that location anyway if the BSP gets - added to the Yocto Project. - For an example showing how to change the BSP configuration, see the - "<a class="link" href="#changing-the-bsp-configuration" target="_top">Changing the BSP Configuration</a>" - section in the Yocto Project Development Manual. - For a better understanding of working with a local clone of the kernel repository - and a local bare clone of the kernel, see the - "<a class="link" href="#modifying-the-kernel-source-code" target="_top">Modifying the Kernel - Source Code</a>" section also in the Yocto Project Development Manual. - </p><p> - In general, however, the Yocto Project maintainers take care of moving the - <code class="filename">SRC_URI</code>-specified - configuration options to the kernel's <code class="filename">meta</code> branch. - Not only is it easier for BSP developers to not have to worry about putting those - configurations in the branch, but having the maintainers do it allows them to apply - 'global' knowledge about the kinds of common configuration options multiple BSPs in - the tree are typically using. - This allows for promotion of common configurations into common features. - </p></div></div></div><div class="section" title="1.3. Requirements and Recommendations for Released BSPs"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="requirements-and-recommendations-for-released-bsps"></a>1.3. Requirements and Recommendations for Released BSPs</h2></div></div></div><p> - Certain requirements exist for a released BSP to be considered - compliant with the Yocto Project. - Additionally, a single recommendation also exists. - This section describes the requirements and recommendation for - released BSPs. - </p><div class="section" title="1.3.1. Released BSP Requirements"><div class="titlepage"><div><div><h3 class="title"><a id="released-bsp-requirements"></a>1.3.1. Released BSP Requirements</h3></div></div></div><p> - Before looking at BSP requirements, you should consider the following: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>The requirements here assume the BSP layer is a well-formed, "legal" - layer that can be added to the Yocto Project. - For guidelines on creating a layer that meets these base requirements, see the - "<a class="link" href="#bsp-layers" title="1.1. BSP Layers">BSP Layers</a>" and the - "<a class="link" href="#understanding-and-creating-layers" target="_top">Understanding - and Creating Layers"</a> in the Yocto Project Development Manual.</p></li><li class="listitem"><p>The requirements in this section apply regardless of how you - ultimately package a BSP. - You should consult the packaging and distribution guidelines for your - specific release process. - For an example of packaging and distribution requirements, see the - <a class="ulink" href="https://wiki.yoctoproject.org/wiki/Third_Party_BSP_Release_Process" target="_top">Third - Party BSP Release Process</a> wiki page.</p></li><li class="listitem"><p>The requirements for the BSP as it is made available to a developer - are completely independent of the released form of the BSP. - For example, the BSP metadata can be contained within a Git repository - and could have a directory structure completely different from what appears - in the officially released BSP layer.</p></li><li class="listitem"><p>It is not required that specific packages or package - modifications exist in the BSP layer, beyond the requirements for general - compliance with the Yocto Project. - For example, no requirement exists dictating that a specific kernel or - kernel version be used in a given BSP.</p></li></ul></div><p> - </p><p> - Following are the requirements for a released BSP that conforms to the - Yocto Project: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><span class="emphasis"><em>Layer Name:</em></span> - The BSP must have a layer name that follows the Yocto - Project standards. - For information on BSP layer names, see the - "<a class="link" href="#bsp-layers" title="1.1. BSP Layers">BSP Layers</a>" section. - </p></li><li class="listitem"><p><span class="emphasis"><em>File System Layout:</em></span> - When possible, use the same directory names in your - BSP layer as listed in the <code class="filename">recipes.txt</code> file. - In particular, you should place recipes - (<code class="filename">.bb</code> files) and recipe - modifications (<code class="filename">.bbappend</code> files) into - <code class="filename">recipes-*</code> subdirectories by functional area - as outlined in <code class="filename">recipes.txt</code>. - If you cannot find a category in <code class="filename">recipes.txt</code> - to fit a particular recipe, you can make up your own - <code class="filename">recipe-*</code> subdirectory. - You can find <code class="filename">recipes.txt</code> in the - <code class="filename">meta</code> directory of the - <a class="link" href="#source-directory" target="_top">source directory</a>, - or in the OpenEmbedded Core Layer - (<code class="filename">openembedded-core</code>) found at - <a class="ulink" href="http://git.openembedded.org/openembedded-core/tree/meta" target="_top">http://git.openembedded.org/openembedded-core/tree/meta</a>. - </p><p>Within any particular <code class="filename">recipes-*</code> category, the layout - should match what is found in the OpenEmbedded Core - Git repository (<code class="filename">openembedded-core</code>) - or the source directory (<code class="filename">poky</code>). - In other words, make sure you place related files in appropriately - related <code class="filename">recipes-*</code> subdirectories specific to the - recipe's function, or within a subdirectory containing a set of closely-related - recipes. - The recipes themselves should follow the general guidelines - for recipes used in the Yocto Project found in the - <a class="ulink" href="https://wiki.yoctoproject.org/wiki/Recipe_%26_Patch_Style_Guide" target="_top">Yocto - Recipe and Patch Style Guide</a>.</p></li><li class="listitem"><p><span class="emphasis"><em>License File:</em></span> - You must include a license file in the - <code class="filename">meta-<bsp_name></code> directory. - This license covers the BSP metadata as a whole. - You must specify which license to use since there is no - default license if one is not specified. - See the - <a class="ulink" href="http://git.yoctoproject.org/cgit.cgi/meta-intel/tree/meta-fishriver/COPYING.MIT" target="_top"><code class="filename">COPYING.MIT</code></a> - file for the Fish River BSP in the <code class="filename">meta-fishriver</code> BSP layer - as an example.</p></li><li class="listitem"><p><span class="emphasis"><em>README File:</em></span> - You must include a <code class="filename">README</code> file in the - <code class="filename">meta-<bsp_name></code> directory. - See the - <a class="ulink" href="http://git.yoctoproject.org/cgit.cgi/meta-intel/tree/meta-fishriver/README" target="_top"><code class="filename">README</code></a> - file for the Fish River BSP in the <code class="filename">meta-fishriver</code> BSP layer - as an example.</p><p>At a minimum, the <code class="filename">README</code> file should - contain the following: - </p><div class="itemizedlist"><ul class="itemizedlist" type="circle"><li class="listitem"><p>A brief description about the hardware the BSP - targets.</p></li><li class="listitem"><p>A list of all the dependencies a - on which a BSP layer depends. - These dependencies are typically a list of required layers needed - to build the BSP. - However, the dependencies should also contain information regarding - any other dependencies the BSP might have.</p></li><li class="listitem"><p>Any required special licensing information. - For example, this information includes information on - special variables needed to satisfy a EULA, - or instructions on information needed to build or distribute - binaries built from the BSP metadata.</p></li><li class="listitem"><p>The name and contact information for the - BSP layer maintainer. - This is the person to whom patches and questions should - be sent.</p></li><li class="listitem"><p>Instructions on how to build the BSP using the BSP - layer.</p></li><li class="listitem"><p>Instructions on how to boot the BSP build from - the BSP layer.</p></li><li class="listitem"><p>Instructions on how to boot the binary images - contained in the <code class="filename">/binary</code> directory, - if present.</p></li><li class="listitem"><p>Information on any known bugs or issues that users - should know about when either building or booting the BSP - binaries.</p></li></ul></div></li><li class="listitem"><p><span class="emphasis"><em>README.sources File:</em></span> - You must include a <code class="filename">README.sources</code> in the - <code class="filename">meta-<bsp_name></code> directory. - This file specifies exactly where you can find the sources used to - generate the binary images contained in the - <code class="filename">/binary</code> directory, if present. - See the - <a class="ulink" href="http://git.yoctoproject.org/cgit.cgi/meta-intel/tree/meta-fishriver/README.sources" target="_top"><code class="filename">README.sources</code></a> - file for the Fish River BSP in the <code class="filename">meta-fishriver</code> BSP layer - as an example.</p></li><li class="listitem"><p><span class="emphasis"><em>Layer Configuration File:</em></span> - You must include a <code class="filename">conf/layer.conf</code> in the - <code class="filename">meta-<bsp_name></code> directory. - This file identifies the <code class="filename">meta-<bsp_name></code> - BSP layer as a layer to the build system.</p></li><li class="listitem"><p><span class="emphasis"><em>Machine Configuration File:</em></span> - You must include a <code class="filename">conf/machine/<bsp_name>.conf</code> - in the <code class="filename">meta-<bsp_name></code> directory. - This configuration file defines a machine target that can be built - using the BSP layer. - Multiple machine configuration files define variations of machine - configurations that are supported by the BSP. - If a BSP supports more multiple machine variations, you need to - adequately describe each variation in the BSP - <code class="filename">README</code> file. - Do not use multiple machine configuration files to describe disparate - hardware. - Multiple machine configuration files should describe very similar targets. - If you do have very different targets, you should create a separate - BSP. - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>It is completely possible for a developer to structure the - working repository as a conglomeration of unrelated BSP - files, and to possibly generate specifically targeted 'release' BSPs - from that directory using scripts or some other mechanism. - Such considerations are outside the scope of this document.</div><p> - </p></li></ul></div><p> - </p></div><div class="section" title="1.3.2. Released BSP Recommendations"><div class="titlepage"><div><div><h3 class="title"><a id="released-bsp-recommendations"></a>1.3.2. Released BSP Recommendations</h3></div></div></div><p> - Following are recommendations for a released BSP that conforms to the - Yocto Project: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><span class="emphasis"><em>Bootable Images:</em></span> - BSP releases - can contain one or more bootable images. - Including bootable images allows users to easily try out the BSP - on their own hardware.</p><p>In some cases, it might not be convenient to include a - bootable image. - In this case, you might want to make two versions of the - BSP available: one that contains binary images, and one - that does not. - The version that does not contain bootable images avoids - unnecessary download times for users not interested in the images. - </p><p>If you need to distribute a BSP and include bootable images or build kernel and - filesystems meant to allow users to boot the BSP for evaluation - purposes, you should put the images and artifacts within a - <code class="filename">binary/</code> subdirectory located in the - <code class="filename">meta-<bsp_name></code> directory. - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>If you do include a bootable image as part of the BSP and the image - was built by software covered by the GPL or other open source licenses, - it is your responsibility to understand - and meet all licensing requirements, which could include distribution - of source files.</div></li><li class="listitem"><p><span class="emphasis"><em>Use a Yocto Linux Kernel:</em></span> - Kernel recipes in the BSP should be based on a Yocto Linux kernel. - Basing your recipes on these kernels reduces the costs for maintaining - the BSP and increases its scalability. - See the <code class="filename">Yocto Linux Kernel</code> category in the - <a class="ulink" href="http://git.yoctoproject.org/cgit.cgi" target="_top"><code class="filename">Yocto Source Repositories</code></a> - for these kernels.</p></li></ul></div><p> - </p></div></div><div class="section" title="1.4. Customizing a Recipe for a BSP"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="customizing-a-recipe-for-a-bsp"></a>1.4. Customizing a Recipe for a BSP</h2></div></div></div><p> - If you plan on customizing a recipe for a particular BSP, you need to do the - following: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>Include within the BSP layer a <code class="filename">.bbappend</code> - file for the modified recipe.</p></li><li class="listitem"><p>Place the BSP-specific file in the BSP's recipe - <code class="filename">.bbappend</code> file path under a directory named - after the machine.</p></li></ul></div><p> - </p><p> - To better understand this, consider an example that customizes a recipe by adding - a BSP-specific configuration file named <code class="filename">interfaces</code> to the - <code class="filename">netbase_4.47.bb</code> recipe for machine "xyz". - Do the following: - </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Edit the <code class="filename">netbase_4.47.bbappend</code> file so that it - contains the following: - </p><pre class="literallayout"> - FILESEXTRAPATHS_prepend := "${THISDIR}/files:" - PRINC := "${@int(PRINC) + 2}" - </pre></li><li class="listitem"><p>Create and place the new <code class="filename">interfaces</code> - configuration file in the BSP's layer here: - </p><pre class="literallayout"> - meta-xyz/recipes-core/netbase/files/xyz/interfaces - </pre></li></ol></div><p> - </p></div><div class="section" title="1.5. BSP Licensing Considerations"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="bsp-licensing-considerations"></a>1.5. BSP Licensing Considerations</h2></div></div></div><p> - In some cases, a BSP contains separately licensed Intellectual Property (IP) - for a component or components. - For these cases, you are required to accept the terms of a commercial or other - type of license that requires some kind of explicit End User License Agreement (EULA). - Once the license is accepted, the OpenEmbedded build system can then build and - include the corresponding component in the final BSP image. - If the BSP is available as a pre-built image, you can download the image after - agreeing to the license or EULA. - </p><p> - You could find that some separately licensed components that are essential - for normal operation of the system might not have an unencumbered (or free) - substitute. - Without these essential components, the system would be non-functional. - Then again, you might find that other licensed components that are simply - 'good-to-have' or purely elective do have an unencumbered, free replacement - component that you can use rather than agreeing to the separately licensed component. - Even for components essential to the system, you might find an unencumbered component - that is not identical but will work as a less-capable version of the - licensed version in the BSP recipe. - </p><p> - For cases where you can substitute a free component and still - maintain the system's functionality, the Yocto Project website's - <a class="ulink" href="http://www.yoctoproject.org/download/all?keys=&download_type=1&download_version=" target="_top">BSP - Download Page</a> makes available de-featured BSPs - that are completely free of any IP encumbrances. - For these cases, you can use the substitution directly and - without any further licensing requirements. - If present, these fully de-featured BSPs are named appropriately - different as compared to the names of the respective - encumbered BSPs. - If available, these substitutions are your - simplest and most preferred options. - Use of these substitutions of course assumes the resulting functionality meets - system requirements. - </p><p> - If however, a non-encumbered version is unavailable or - it provides unsuitable functionality or quality, you can use an encumbered - version. - </p><p> - A couple different methods exist within the OpenEmbedded build system to - satisfy the licensing requirements for an encumbered BSP. - The following list describes them in order of preference: - </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p><span class="emphasis"><em>Use the <code class="filename">LICENSE_FLAGS</code> variable - to define the recipes that have commercial or other types of - specially-licensed packages:</em></span> - For each of those recipes, you can - specify a matching license string in a - <code class="filename">local.conf</code> variable named - <code class="filename">LICENSE_FLAGS_WHITELIST</code>. - Specifying the matching license string signifies that you agree to the license. - Thus, the build system can build the corresponding recipe and include - the component in the image. - See the - "<a class="link" href="#enabling-commercially-licensed-recipes" target="_top">Enabling - Commercially Licensed Recipes</a>" section in the Yocto Project Reference - Manual for details on how to use these variables.</p><p>If you build as you normally would, without - specifying any recipes in the - <code class="filename">LICENSE_FLAGS_WHITELIST</code>, the build stops and - provides you with the list of recipes that you have - tried to include in the image that need entries in - the <code class="filename">LICENSE_FLAGS_WHITELIST</code>. - Once you enter the appropriate license flags into the whitelist, - restart the build to continue where it left off. - During the build, the prompt will not appear again - since you have satisfied the requirement.</p><p>Once the appropriate license flags are on the white list - in the <code class="filename">LICENSE_FLAGS_WHITELIST</code> variable, you - can build the encumbered image with no change at all - to the normal build process.</p></li><li class="listitem"><p><span class="emphasis"><em>Get a pre-built version of the BSP:</em></span> - You can get this type of BSP by visiting the Yocto Project website's - <a class="ulink" href="http://www.yoctoproject.org/download" target="_top">Download</a> - page and clicking on "BSP Downloads". - You can download BSP tarballs that contain proprietary components - after agreeing to the licensing - requirements of each of the individually encumbered - packages as part of the download process. - Obtaining the BSP this way allows you to access an encumbered - image immediately after agreeing to the - click-through license agreements presented by the - website. - Note that if you want to build the image - yourself using the recipes contained within the BSP - tarball, you will still need to create an - appropriate <code class="filename">LICENSE_FLAGS_WHITELIST</code> to match the - encumbered recipes in the BSP.</p></li></ol></div><p> - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3> - Pre-compiled images are bundled with - a time-limited kernel that runs for a - predetermined amount of time (10 days) before it forces - the system to reboot. - This limitation is meant to discourage direct redistribution - of the image. - You must eventually rebuild the image if you want to remove this restriction. - </div></div><div class="section" title="1.6. Using the Yocto Project's BSP Tools"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="using-the-yocto-projects-bsp-tools"></a>1.6. Using the Yocto Project's BSP Tools</h2></div></div></div><p> - The Yocto Project includes a couple of tools that enable - you to create a <a class="link" href="#bsp-layers" title="1.1. BSP Layers">BSP layer</a> - from scratch and do basic configuration and maintenance - of the kernel without ever looking at a metadata file. - These tools are <code class="filename">yocto-bsp</code> and <code class="filename">yocto-kernel</code>, - respectively. - </p><p> - The following sections describe the common location and help features as well - as details for the <code class="filename">yocto-bsp</code> and <code class="filename">yocto-kernel</code> - tools. - </p><div class="section" title="1.6.1. Common Features"><div class="titlepage"><div><div><h3 class="title"><a id="common-features"></a>1.6.1. Common Features</h3></div></div></div><p> - Designed to have a command interface somewhat like - <a class="link" href="#git" target="_top">Git</a>, each - tool is structured as a set of sub-commands under a - top-level command. - The top-level command (<code class="filename">yocto-bsp</code> - or <code class="filename">yocto-kernel</code>) itself does - nothing but invoke or provide help on the sub-commands - it supports. - </p><p> - Both tools reside in the <code class="filename">scripts/</code> subdirectory - of the <a class="link" href="#source-directory" target="_top">source directory</a>. - Consequently, to use the scripts, you must <code class="filename">source</code> the - environment just as you would when invoking a build: - </p><pre class="literallayout"> - $ source oe-init-build-env [build_dir] - </pre><p> - </p><p> - The most immediately useful function is to get help on both tools. - The built-in help system makes it easy to drill down at - any time and view the syntax required for any specific command. - Simply enter the name of the command, or the command along with - <code class="filename">help</code> to display a list of the available sub-commands. - Here is an example: - </p><pre class="literallayout"> - $ yocto-bsp - $ yocto-bsp help - - Usage: - - Create a customized Yocto BSP layer. - - usage: yocto-bsp [--version] [--help] COMMAND [ARGS] - - The most commonly used 'yocto-bsp' commands are: - create Create a new Yocto BSP - list List available values for options and BSP properties - - See 'yocto-bsp help COMMAND' for more information on a specific command. - - - Options: - --version show program's version number and exit - -h, --help show this help message and exit - -D, --debug output debug information - </pre><p> - </p><p> - Similarly, entering just the name of a sub-command shows the detailed usage - for that sub-command: - </p><pre class="literallayout"> - $ yocto-bsp create - - Usage: - - Create a new Yocto BSP - usage: yocto-bsp create <bsp-name> <karch> [-o <DIRNAME> | --outdir <DIRNAME>] - [-i <JSON PROPERTY FILE> | --infile <JSON PROPERTY_FILE>] - - This command creates a Yocto BSP based on the specified parameters. - The new BSP will be a new BSP layer contained by default within - the top-level directory specified as 'meta-bsp-name'. The -o option - can be used to place the BSP layer in a directory with a different - name and location. - - ... - </pre><p> - </p><p> - For any sub-command, you can also use the word 'help' just before the - sub-command to get more extensive documentation: - </p><pre class="literallayout"> - $ yocto-bsp help create - - NAME - yocto-bsp create - Create a new Yocto BSP - - SYNOPSIS - yocto-bsp create <bsp-name> <karch> [-o <DIRNAME> | --outdir <DIRNAME>] - [-i <JSON PROPERTY FILE> | --infile <JSON PROPERTY_FILE>] - - DESCRIPTION - This command creates a Yocto BSP based on the specified - parameters. The new BSP will be a new Yocto BSP layer contained - by default within the top-level directory specified as - 'meta-bsp-name'. The -o option can be used to place the BSP layer - in a directory with a different name and location. - - The value of the 'karch' parameter determines the set of files - that will be generated for the BSP, along with the specific set of - 'properties' that will be used to fill out the BSP-specific - portions of the BSP. - - ... - - NOTE: Once created, you should add your new layer to your - bblayers.conf file in order for it to be subsequently seen and - modified by the yocto-kernel tool. - - NOTE for x86- and x86_64-based BSPs: The generated BSP assumes the - presence of the of the meta-intel layer, so you should also have a - meta-intel layer present and added to your bblayers.conf as well. - </pre><p> - </p><p> - Now that you know where these two commands reside and how to access information - on them, you should find it relatively straightforward to discover the commands - necessary to create a BSP and perform basic kernel maintenance on that BSP using - the tools. - The next sections provide a concrete starting point to expand on a few points that - might not be immediately obvious or that could use further explanation. - </p></div><div class="section" title="1.6.2. Creating a new BSP Layer Using the yocto-bsp Script"><div class="titlepage"><div><div><h3 class="title"><a id="creating-a-new-bsp-layer-using-the-yocto-bsp-script"></a>1.6.2. Creating a new BSP Layer Using the yocto-bsp Script</h3></div></div></div><p> - The <code class="filename">yocto-bsp</code> script creates a new - <a class="link" href="#bsp-layers" title="1.1. BSP Layers">BSP layer</a> for any architecture supported - by the Yocto Project, as well as QEMU versions of the same. - The default mode of the script's operation is to prompt you for information needed - to generate the BSP layer. - For the current set of BSPs, the script prompts you for various important - parameters such as: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>which kernel to use</p></li><li class="listitem"><p>which branch of that kernel to use (or re-use)</p></li><li class="listitem"><p>whether or not to use X, and if so, which drivers to use</p></li><li class="listitem"><p>whether to turn on SMP</p></li><li class="listitem"><p>whether the BSP has a keyboard</p></li><li class="listitem"><p>whether the BSP has a touchscreen</p></li><li class="listitem"><p>any remaining configurable items associated with the BSP</p></li></ul></div><p> - </p><p> - You use the <code class="filename">yocto-bsp create</code> sub-command to create - a new BSP layer. - This command requires you to specify a particular architecture on which to - base the BSP. - Assuming you have sourced the environment, you can use the - <code class="filename">yocto-bsp list karch</code> sub-command to list the - architectures available for BSP creation as follows: - </p><pre class="literallayout"> - $ yocto-bsp list karch - Architectures available: - arm - powerpc - i386 - mips - x86_64 - qemu - </pre><p> - </p><p> - The remainder of this section presents an example that uses - <code class="filename">myarm</code> as the machine name and <code class="filename">qemu</code> - as the machine architecture. - Of the available architectures, <code class="filename">qemu</code> is the only architecture - that causes the script to prompt you further for an actual architecture. - In every other way, this architecture is representative of how creating a BSP for - a 'real' machine would work. - The reason the example uses this architecture is because it is an emulated architecture - and can easily be followed without requiring actual hardware. - </p><p> - As the <code class="filename">yocto-bsp create</code> command runs, default values for - the prompts appear in brackets. - Pressing enter without supplying anything on the command line or pressing enter - and providing an invalid response causes the script to accept the default value. - </p><p> - Following is the complete example: - </p><pre class="literallayout"> - $ yocto-bsp create myarm qemu - Which qemu architecture would you like to use? [default: x86] - 1) common 32-bit x86 - 2) common 64-bit x86 - 3) common 32-bit ARM - 4) common 32-bit PowerPC - 5) common 32-bit MIPS - 3 - Would you like to use the default (3.2) kernel? (Y/n) - Do you need a new machine branch for this BSP (the alternative is to re-use an existing branch)? [Y/n] - Getting branches from remote repo git://git.yoctoproject.org/linux-yocto-3.2... - Please choose a machine branch to base this BSP on => [default: standard/default/common-pc] - 1) base - 2) standard/base - 3) standard/default/arm-versatile-926ejs - 4) standard/default/base - 5) standard/default/beagleboard - 6) standard/default/cedartrailbsp (copy).xml - 7) standard/default/common-pc-64/base - 8) standard/default/common-pc-64/jasperforest - 9) standard/default/common-pc-64/romley - 10) standard/default/common-pc-64/sugarbay - 11) standard/default/common-pc/atom-pc - 12) standard/default/common-pc/base - 13) standard/default/crownbay - 14) standard/default/emenlow - 15) standard/default/fishriver - 16) standard/default/fri2 - 17) standard/default/fsl-mpc8315e-rdb - 18) standard/default/mti-malta32-be - 19) standard/default/mti-malta32-le - 20) standard/default/preempt-rt - 21) standard/default/qemu-ppc32 - 22) standard/default/routerstationpro - 23) standard/preempt-rt/base - 24) standard/preempt-rt/qemu-ppc32 - 25) standard/preempt-rt/routerstationpro - 26) standard/tiny - 3 - Do you need SMP support? (Y/n) - Does your BSP have a touchscreen? (y/N) - Does your BSP have a keyboard? (Y/n) - New qemu BSP created in meta-myarm - </pre><p> - Let's take a closer look at the example now: - </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>For the <code class="filename">qemu</code> architecture, - the script first prompts you for which emulated architecture to use. - In the example, we use the <code class="filename">arm</code> architecture. - </p></li><li class="listitem"><p>The script then prompts you for the kernel. - The default kernel is 3.2 and is acceptable. - So, the example accepts the default. - If you enter 'n', the script prompts you to further enter the kernel - you do want to use (e.g. 3.0, 3.2_preempt-rt, etc.).</p></li><li class="listitem"><p>Next, the script asks whether you would like to have a new - branch created especially for your BSP in the local - <a class="link" href="#local-kernel-files" target="_top">Linux Yocto Kernel</a> - Git repository . - If not, then the script re-uses an existing branch.</p><p>In this example, the default (or 'yes') is accepted. - Thus, a new branch is created for the BSP rather than using a common, shared - branch. - The new branch is the branch committed to for any patches you might later add. - The reason a new branch is the default is that typically - new BSPs do require BSP-specific patches. - The tool thus assumes that most of time a new branch is required. - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>In the current implementation, creation or re-use of a branch does - not actually matter. - The reason is because the generated BSPs assume that patches and - configurations live in recipe-space, which is something that can be done - with or without a dedicated branch. - Generated BSPs, however, are different. - This difference becomes significant once the tool's 'publish' functionality - is implemented.</div></li><li class="listitem"><p>Regardless of which choice is made in the previous step, - you are now given the opportunity to select a particular machine branch on - which to base your new BSP-specific machine branch on - (or to re-use if you had elected to not create a new branch). - Because this example is generating an <code class="filename">arm</code> BSP, the example - uses <code class="filename">#3</code> at the prompt, which selects the arm-versatile branch. - </p></li><li class="listitem"><p>The remainder of the prompts are routine. - Defaults are accepted for each.</p></li><li class="listitem"><p>By default, the script creates the new BSP Layer in the - <a class="link" href="#build-directory" target="_top">build directory</a>. - </p></li></ol></div><p> - </p><p> - Once the BSP Layer is created, you must add it to your - <code class="filename">bblayers.conf</code> file. - Here is an example: - </p><pre class="literallayout"> - BBLAYERS = " \ - /usr/local/src/yocto/meta \ - /usr/local/src/yocto/meta-yocto \ - /usr/local/src/yocto/meta-myarm \ - " - </pre><p> - Adding the layer to this file allows the build system to build the BSP and - the <code class="filename">yocto-kernel</code> tool to be able to find the layer and - other metadata it needs on which to operate. - </p></div><div class="section" title="1.6.3. Managing Kernel Patches and Config Items with yocto-kernel"><div class="titlepage"><div><div><h3 class="title"><a id="managing-kernel-patches-and-config-items-with-yocto-kernel"></a>1.6.3. Managing Kernel Patches and Config Items with yocto-kernel</h3></div></div></div><p> - Assuming you have created a <a class="link" href="#bsp-layers" title="1.1. BSP Layers">BSP Layer</a> using - <a class="link" href="#creating-a-new-bsp-layer-using-the-yocto-bsp-script" title="1.6.2. Creating a new BSP Layer Using the yocto-bsp Script"> - <code class="filename">yocto-bsp</code></a> and you added it to your - <a class="link" href="#var-BBLAYERS" target="_top"><code class="filename">BBLAYERS</code></a> - variable in the <code class="filename">bblayers.conf</code> file, you can now use - the <code class="filename">yocto-kernel</code> script to add patches and configuration - items to the BSP's kernel. - </p><p> - The <code class="filename">yocto-kernel</code> script allows you to add, remove, and list patches - and kernel config settings to a BSP's kernel - <code class="filename">.bbappend</code> file. - All you need to do is use the appropriate sub-command. - Recall that the easiest way to see exactly what sub-commands are available - is to use the <code class="filename">yocto-kernel</code> built-in help as follows: - </p><pre class="literallayout"> - $ yocto-kernel - Usage: - - Modify and list Yocto BSP kernel config items and patches. - - usage: yocto-kernel [--version] [--help] COMMAND [ARGS] - - The most commonly used 'yocto-kernel' commands are: - config list List the modifiable set of bare kernel config options for a BSP - config add Add or modify bare kernel config options for a BSP - config rm Remove bare kernel config options from a BSP - patch list List the patches associated with a BSP - patch add Patch the Yocto kernel for a BSP - patch rm Remove patches from a BSP - - See 'yocto-kernel help COMMAND' for more information on a specific command. - </pre><p> - </p><p> - The <code class="filename">yocto-kernel patch add</code> sub-command allows you to add a - patch to a BSP. - The following example adds two patches to the <code class="filename">myarm</code> BSP: - </p><pre class="literallayout"> - $ yocto-kernel patch add myarm ~/test.patch - Added patches: - test.patch - - $ yocto-kernel patch add myarm ~/yocto-testmod.patch - Added patches: - yocto-testmod.patch - </pre><p> - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>Although the previous example adds patches one at a time, it is possible - to add multiple patches at the same time.</div><p> - </p><p> - You can verify patches have been added by using the - <code class="filename">yocto-kernel patch list</code> sub-command. - Here is an example: - </p><pre class="literallayout"> - $ yocto-kernel patch list myarm - The current set of machine-specific patches for myarm is: - 1) test.patch - 2) yocto-testmod.patch - </pre><p> - </p><p> - You can also use the <code class="filename">yocto-kernel</code> script to - remove a patch using the <code class="filename">yocto-kernel patch rm</code> sub-command. - Here is an example: - </p><pre class="literallayout"> - $ yocto-kernel patch rm myarm - Specify the patches to remove: - 1) test.patch - 2) yocto-testmod.patch - 1 - Removed patches: - test.patch - </pre><p> - </p><p> - Again, using the <code class="filename">yocto-kernel patch list</code> sub-command, - you can verify that the patch was in fact removed: - </p><pre class="literallayout"> - $ yocto-kernel patch list myarm - The current set of machine-specific patches for myarm is: - 1) yocto-testmod.patch - </pre><p> - </p><p> - In a completely similar way, you can use the <code class="filename">yocto-kernel config add</code> - sub-command to add one or more kernel config item settings to a BSP. - The following commands add a couple of config items to the - <code class="filename">myarm</code> BSP: - </p><pre class="literallayout"> - $ yocto-kernel config add myarm CONFIG_MISC_DEVICES=y - Added items: - CONFIG_MISC_DEVICES=y - - $ yocto-kernel config add myarm KCONFIG_YOCTO_TESTMOD=y - Added items: - CONFIG_YOCTO_TESTMOD=y - </pre><p> - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>Although the previous example adds config items one at a time, it is possible - to add multiple config items at the same time.</div><p> - </p><p> - You can list the config items now associated with the BSP. - Doing so shows you the config items you added as well as others associated - with the BSP: - </p><pre class="literallayout"> - $ yocto-kernel config list myarm - The current set of machine-specific kernel config items for myarm is: - 1) CONFIG_MISC_DEVICES=y - 2) CONFIG_YOCTO_TESTMOD=y - </pre><p> - </p><p> - Finally, you can remove one or more config items using the - <code class="filename">yocto-kernel config rm</code> sub-command in a manner - completely analogous to <code class="filename">yocto-kernel patch rm</code>. - </p></div></div></div> - - - -</div> - -<table border="0" summary="manufactured viewport for HTML img" cellspacing="0" cellpadding="0" width="100%"><tr><td align="left"><img src="figures/kernel-title.png" align="left" width="100%" /></td></tr></table> - - <div xml:lang="en" class="book" lang="en"><div class="titlepage"><div><div><h1 class="title"><a id="kernel-manual"></a></h1></div><div><div class="authorgroup"> - <div class="author"><h3 class="author"><span class="firstname">Bruce</span> <span class="surname">Ashfield</span></h3><div class="affiliation"> - <span class="orgname">Wind River Corporation<br /></span> - </div><code class="email"><<a class="email" href="mailto:bruce.ashfield@windriver.com">bruce.ashfield@windriver.com</a>></code></div> - </div></div><div><p class="copyright">Copyright © 2010-2012 Linux Foundation</p></div><div><div class="legalnotice" title="Legal Notice"><a id="id1504523"></a> - <p> - Permission is granted to copy, distribute and/or modify this document under - the terms of the <a class="ulink" href="http://creativecommons.org/licenses/by-sa/2.0/uk/" target="_top">Creative Commons Attribution-Share Alike 2.0 UK: England & Wales</a> as published by Creative Commons. - </p> - <div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3> - Due to production processes, there could be differences between the Yocto Project - documentation bundled in the release tarball and the - Yocto Project Kernel Architecture and Use Manual on - the <a class="ulink" href="http://www.yoctoproject.org" target="_top">Yocto Project</a> website. - For the latest version of this manual, see the manual on the website. - </div> - </div></div><div><div class="revhistory"><table border="1" width="100%" summary="Revision history"><tr><th align="left" valign="top" colspan="2"><b>Revision History</b></th></tr> - <tr><td align="left">Revision 0.9</td><td align="left">24 November 2010</td></tr><tr><td align="left" colspan="2">The initial document draft released with the Yocto Project 0.9 Release.</td></tr> - <tr><td align="left">Revision 1.0</td><td align="left">6 April 2011</td></tr><tr><td align="left" colspan="2">Released with the Yocto Project 1.0 Release.</td></tr> - <tr><td align="left">Revision 1.0.1</td><td align="left">23 May 2011</td></tr><tr><td align="left" colspan="2">Released with the Yocto Project 1.0.1 Release.</td></tr> - <tr><td align="left">Revision 1.1</td><td align="left">6 October 2011</td></tr><tr><td align="left" colspan="2">Released with the Yocto Project 1.1 Release.</td></tr> - <tr><td align="left">Revision 1.2</td><td align="left">April 2012</td></tr><tr><td align="left" colspan="2">Released with the Yocto Project 1.2 Release.</td></tr> - <tr><td align="left">Revision 1.3</td><td align="left">Sometime in 2012</td></tr><tr><td align="left" colspan="2">Released with the Yocto Project 1.3 Release.</td></tr> - </table></div></div></div><hr /></div> - - - <div class="chapter" title="Chapter 1. Yocto Project Kernel Architecture and Use Manual"><div class="titlepage"><div><div><h2 class="title"><a id="kernel-doc-intro"></a>Chapter 1. Yocto Project Kernel Architecture and Use Manual</h2></div></div></div><div class="toc"><dl><dt><span class="section"><a href="#kernel-intro-section">1.1. Introduction</a></span></dt></dl></div><div class="section" title="1.1. Introduction"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="kernel-intro-section"></a>1.1. Introduction</h2></div></div></div><p> - The Yocto Project presents kernels as a fully patched, history-clean Git - repositories. - Each repository represents selected features, board support, - and configurations extensively tested by the Yocto Project. - Yocto Project kernels allow the end user to leverage community - best practices to seamlessly manage the development, build and debug cycles. - </p><p> - This manual describes Yocto Project kernels by providing information - on history, organization, benefits, and use. - The manual consists of two sections: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><span class="emphasis"><em>Concepts:</em></span> Describes concepts behind a kernel. - You will understand how a kernel is organized and why it is organized in - the way it is. You will understand the benefits of a kernel's organization - and the mechanisms used to work with the kernel and how to apply it in your - design process.</p></li><li class="listitem"><p><span class="emphasis"><em>Using a Kernel:</em></span> Describes best practices - and "how-to" information - that lets you put a kernel to practical use. - Some examples are how to examine changes in a branch and how to - save kernel modifications.</p></li></ul></div><p> - </p><p> - For more information on the Linux kernel, see the following links: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>The Linux Foundation's guide for kernel development - process - <a class="ulink" href="http://ldn.linuxfoundation.org/book/1-a-guide-kernel-development-process" target="_top">http://ldn.linuxfoundation.org/book/1-a-guide-kernel-development-process</a></p></li><li class="listitem"><p>A fairly encompassing guide on Linux kernel development - - <a class="ulink" href="http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=blob_plain;f=Documentation/HOWTO;hb=HEAD" target="_top">http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=blob_plain;f=Documentation/HOWTO;hb=HEAD</a></p></li></ul></div><p> - </p><p> - For more discussion on the Yocto Project kernel, you can see these sections - in the Yocto Project Development Manual: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p> - "<a class="link" href="#kernel-overview" target="_top">Kernel Overview</a>"</p></li><li class="listitem"><p> - "<a class="link" href="#kernel-modification-workflow" target="_top">Kernel Modification Workflow</a>" - </p></li><li class="listitem"><p> - "<a class="link" href="#dev-manual-kernel-appendix" target="_top">Kernel Modification Example</a>"</p></li></ul></div><p> - </p><p> - For general information on the Yocto Project, visit the website at - <a class="ulink" href="http://www.yoctoproject.org" target="_top">http://www.yoctoproject.org</a>. - </p></div></div> - - <div class="chapter" title="Chapter 2. Yocto Project Kernel Concepts"><div class="titlepage"><div><div><h2 class="title"><a id="kernel-concepts"></a>Chapter 2. Yocto Project Kernel Concepts</h2></div></div></div><div class="toc"><dl><dt><span class="section"><a href="#concepts-org">2.1. Introduction</a></span></dt><dt><span class="section"><a href="#kernel-goals">2.2. Kernel Goals</a></span></dt><dt><span class="section"><a href="#kernel-big-picture">2.3. Yocto Project Kernel Development and Maintenance Overview</a></span></dt><dt><span class="section"><a href="#kernel-architecture">2.4. Kernel Architecture</a></span></dt><dd><dl><dt><span class="section"><a href="#architecture-overview">2.4.1. Overview</a></span></dt><dt><span class="section"><a href="#branching-and-workflow">2.4.2. Branching Strategy and Workflow</a></span></dt><dt><span class="section"><a href="#source-code-manager-git">2.4.3. Source Code Manager - Git</a></span></dt></dl></dd><dt><span class="section"><a href="#kernel-configuration">2.5. Kernel Configuration</a></span></dt><dt><span class="section"><a href="#kernel-tools">2.6. Kernel Tools</a></span></dt></dl></div><div class="section" title="2.1. Introduction"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="concepts-org"></a>2.1. Introduction</h2></div></div></div><p> - This chapter provides conceptual information about the kernel: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>Kernel Goals</p></li><li class="listitem"><p>Kernel Development and Maintenance Overview</p></li><li class="listitem"><p>Kernel Architecture</p></li><li class="listitem"><p>Kernel Tools</p></li></ul></div><p> - </p></div><div class="section" title="2.2. Kernel Goals"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="kernel-goals"></a>2.2. Kernel Goals</h2></div></div></div><p> - The complexity of embedded kernel design has increased dramatically. - Whether it is managing multiple implementations of a particular feature or tuning and - optimizing board specific features, both flexibility and maintainability are key concerns. - The Linux kernels available through the Yocto Project are presented with the embedded - developer's needs in mind and have evolved to assist in these key concerns. - For example, prior methods such as applying hundreds of patches to an extracted - tarball have been replaced with proven techniques that allow easy inspection, - bisection and analysis of changes. - Application of these techniques also creates a platform for performing integration and - collaboration with the thousands of upstream development projects. - </p><p> - With all these considerations in mind, the Yocto Project's kernel and development team - strives to attain these goals: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>Allow the end user to leverage community best practices to seamlessly - manage the development, build and debug cycles.</p></li><li class="listitem"><p>Create a platform for performing integration and collaboration with the - thousands of upstream development projects that exist.</p></li><li class="listitem"><p>Provide mechanisms that support many different work flows, front-ends and - management techniques.</p></li><li class="listitem"><p>Deliver the most up-to-date kernel possible while still ensuring that - the baseline kernel is the most stable official release.</p></li><li class="listitem"><p>Include major technological features as part of the Yocto Project's - upward revision strategy.</p></li><li class="listitem"><p>Present a kernel Git repository that, similar to the upstream - <code class="filename">kernel.org</code> tree, - has a clear and continuous history.</p></li><li class="listitem"><p>Deliver a key set of supported kernel types, where each type is tailored - to meet a specific use (e.g. networking, consumer, devices, and so forth).</p></li><li class="listitem"><p>Employ a Git branching strategy that, from a developer's point of view, - results in a linear path from the baseline <code class="filename">kernel.org</code>, - through a select group of features and - ends with their BSP-specific commits.</p></li></ul></div><p> - </p></div><div class="section" title="2.3. Yocto Project Kernel Development and Maintenance Overview"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="kernel-big-picture"></a>2.3. Yocto Project Kernel Development and Maintenance Overview</h2></div></div></div><p> - Kernels available through the Yocto Project, like other kernels, are based off the Linux - kernel releases from <a class="ulink" href="http://www.kernel.org" target="_top">http://www.kernel.org</a>. - At the beginning of a major development cycle, the Yocto Project team - chooses its kernel based on factors such as release timing, the anticipated release - timing of final upstream <code class="filename">kernel.org</code> versions, and Yocto Project - feature requirements. - Typically, the kernel chosen is in the - final stages of development by the community. - In other words, the kernel is in the release - candidate or "rc" phase and not yet a final release. - But, by being in the final stages of external development, the team knows that the - <code class="filename">kernel.org</code> final release will clearly be within the early stages of - the Yocto Project development window. - </p><p> - This balance allows the team to deliver the most up-to-date kernel - as possible, while still ensuring that the team has a stable official release for - the baseline Linux kernel version. - </p><p> - The ultimate source for kernels available through the Yocto Project are released kernels - from <code class="filename">kernel.org</code>. - In addition to a foundational kernel from <code class="filename">kernel.org</code>, the - kernels available contain a mix of important new mainline - developments, non-mainline developments (when there is no alternative), - Board Support Package (BSP) developments, - and custom features. - These additions result in a commercially released Yocto Project Linux kernel that caters - to specific embedded designer needs for targeted hardware. - </p><p> - Once a kernel is officially released, the Yocto Project team goes into - their next development cycle, or upward revision (uprev) cycle, while still - continuing maintenance on the released kernel. - It is important to note that the most sustainable and stable way - to include feature development upstream is through a kernel uprev process. - Back-porting hundreds of individual fixes and minor features from various - kernel versions is not sustainable and can easily compromise quality. - </p><p> - During the uprev cycle, the Yocto Project team uses an ongoing analysis of - kernel development, BSP support, and release timing to select the best - possible <code class="filename">kernel.org</code> version. - The team continually monitors community kernel - development to look for significant features of interest. - The team does consider back-porting large features if they have a significant advantage. - User or community demand can also trigger a back-port or creation of new - functionality in the Yocto Project baseline kernel during the uprev cycle. - </p><p> - Generally speaking, every new kernel both adds features and introduces new bugs. - These consequences are the basic properties of upstream kernel development and are - managed by the Yocto Project team's kernel strategy. - It is the Yocto Project team's policy to not back-port minor features to the released kernel. - They only consider back-porting significant technological jumps - and, that is done - after a complete gap analysis. - The reason for this policy is that back-porting any small to medium sized change - from an evolving kernel can easily create mismatches, incompatibilities and very - subtle errors. - </p><p> - These policies result in both a stable and a cutting - edge kernel that mixes forward ports of existing features and significant and critical - new functionality. - Forward porting functionality in the kernels available through the Yocto Project kernel - can be thought of as a "micro uprev." - The many “micro uprevs” produce a kernel version with a mix of - important new mainline, non-mainline, BSP developments and feature integrations. - This kernel gives insight into new features and allows focused - amounts of testing to be done on the kernel, which prevents - surprises when selecting the next major uprev. - The quality of these cutting edge kernels is evolving and the kernels are used in leading edge - feature and BSP development. - </p></div><div class="section" title="2.4. Kernel Architecture"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="kernel-architecture"></a>2.4. Kernel Architecture</h2></div></div></div><p> - This section describes the architecture of the kernels available through the - Yocto Project and provides information - on the mechanisms used to achieve that architecture. - </p><div class="section" title="2.4.1. Overview"><div class="titlepage"><div><div><h3 class="title"><a id="architecture-overview"></a>2.4.1. Overview</h3></div></div></div><p> - As mentioned earlier, a key goal of the Yocto Project is to present the - developer with - a kernel that has a clear and continuous history that is visible to the user. - The architecture and mechanisms used achieve that goal in a manner similar to the - upstream <code class="filename">kernel.org</code>. - </p><p> - You can think of a Yocto Project kernel as consisting of a baseline Linux kernel with - added features logically structured on top of the baseline. - The features are tagged and organized by way of a branching strategy implemented by the - source code manager (SCM) Git. - For information on Git as applied to the Yocto Project, see the - "<a class="link" href="#git" target="_top">Git</a>" section in the - Yocto Project Development Manual. - </p><p> - The result is that the user has the ability to see the added features and - the commits that make up those features. - In addition to being able to see added features, the user can also view the history of what - made up the baseline kernel. - </p><p> - The following illustration shows the conceptual Yocto Project kernel. - </p><p> - </p><table border="0" summary="manufactured viewport for HTML img" cellspacing="0" cellpadding="0" width="540"><tr style="height: 630px"><td align="center"><img src="figures/kernel-architecture-overview.png" align="middle" /></td></tr></table><p> - </p><p> - In the illustration, the "Kernel.org Branch Point" - marks the specific spot (or release) from - which the Yocto Project kernel is created. - From this point "up" in the tree, features and differences are organized and tagged. - </p><p> - The "Yocto Project Baseline Kernel" contains functionality that is common to every kernel - type and BSP that is organized further up the tree. - Placing these common features in the - tree this way means features don't have to be duplicated along individual branches of the - structure. - </p><p> - From the Yocto Project Baseline Kernel, branch points represent specific functionality - for individual BSPs as well as real-time kernels. - The illustration represents this through three BSP-specific branches and a real-time - kernel branch. - Each branch represents some unique functionality for the BSP or a real-time kernel. - </p><p> - In this example structure, the real-time kernel branch has common features for all - real-time kernels and contains - more branches for individual BSP-specific real-time kernels. - The illustration shows three branches as an example. - Each branch points the way to specific, unique features for a respective real-time - kernel as they apply to a given BSP. - </p><p> - The resulting tree structure presents a clear path of markers (or branches) to the - developer that, for all practical purposes, is the kernel needed for any given set - of requirements. - </p></div><div class="section" title="2.4.2. Branching Strategy and Workflow"><div class="titlepage"><div><div><h3 class="title"><a id="branching-and-workflow"></a>2.4.2. Branching Strategy and Workflow</h3></div></div></div><p> - The Yocto Project team creates kernel branches at points where functionality is - no longer shared and thus, needs to be isolated. - For example, board-specific incompatibilities would require different functionality - and would require a branch to separate the features. - Likewise, for specific kernel features, the same branching strategy is used. - </p><p> - This branching strategy results in a tree that has features organized to be specific - for particular functionality, single kernel types, or a subset of kernel types. - This strategy also results in not having to store the same feature twice - internally in the tree. - Rather, the kernel team stores the unique differences required to apply the - feature onto the kernel type in question. - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3> - The Yocto Project team strives to place features in the tree such that they can be - shared by all boards and kernel types where possible. - However, during development cycles or when large features are merged, - the team cannot always follow this practice. - In those cases, the team uses isolated branches to merge features. - </div><p> - </p><p> - BSP-specific code additions are handled in a similar manner to kernel-specific additions. - Some BSPs only make sense given certain kernel types. - So, for these types, the team creates branches off the end of that kernel type for all - of the BSPs that are supported on that kernel type. - From the perspective of the tools that create the BSP branch, the BSP is really no - different than a feature. - Consequently, the same branching strategy applies to BSPs as it does to features. - So again, rather than store the BSP twice, the team only stores the unique - differences for the BSP across the supported multiple kernels. - </p><p> - While this strategy can result in a tree with a significant number of branches, it is - important to realize that from the developer's point of view, there is a linear - path that travels from the baseline <code class="filename">kernel.org</code>, through a select - group of features and ends with their BSP-specific commits. - In other words, the divisions of the kernel are transparent and are not relevant - to the developer on a day-to-day basis. - From the developer's perspective, this path is the "master" branch. - The developer does not need to be aware of the existence of any other branches at all. - Of course, there is value in the existence of these branches - in the tree, should a person decide to explore them. - For example, a comparison between two BSPs at either the commit level or at the line-by-line - code <code class="filename">diff</code> level is now a trivial operation. - </p><p> - Working with the kernel as a structured tree follows recognized community best practices. - In particular, the kernel as shipped with the product, should be - considered an "upstream source" and viewed as a series of - historical and documented modifications (commits). - These modifications represent the development and stabilization done - by the Yocto Project kernel development team. - </p><p> - Because commits only change at significant release points in the product life cycle, - developers can work on a branch created - from the last relevant commit in the shipped Yocto Project kernel. - As mentioned previously, the structure is transparent to the developer - because the kernel tree is left in this state after cloning and building the kernel. - </p></div><div class="section" title="2.4.3. Source Code Manager - Git"><div class="titlepage"><div><div><h3 class="title"><a id="source-code-manager-git"></a>2.4.3. Source Code Manager - Git</h3></div></div></div><p> - The Source Code Manager (SCM) is Git. - This SCM is the obvious mechanism for meeting the previously mentioned goals. - Not only is it the SCM for <code class="filename">kernel.org</code> but, - Git continues to grow in popularity and supports many different work flows, - front-ends and management techniques. - </p><p> - You can find documentation on Git at <a class="ulink" href="http://git-scm.com/documentation" target="_top">http://git-scm.com/documentation</a>. - You can also get an introduction to Git as it applies to the Yocto Project in the - "<a class="link" href="#git" target="_top">Git</a>" - section in the Yocto Project Development Manual. - These referenced sections overview Git and describe a minimal set of - commands that allows you to be functional using Git. - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3> - You can use as much, or as little, of what Git has to offer to accomplish what - you need for your project. - You do not have to be a "Git Master" in order to use it with the Yocto Project. - </div><p> - </p></div></div><div class="section" title="2.5. Kernel Configuration"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="kernel-configuration"></a>2.5. Kernel Configuration</h2></div></div></div><p> - Kernel configuration, along with kernel features, defines how a kernel - image is built for the Yocto Project. - Through configuration settings, you can customize a Yocto Project kernel to be - specific to particular hardware. - For example, you can specify sound support or networking support. - This section describes basic concepts behind Kernel configuration within the - Yocto Project and references you to other areas for specific configuration - applications. - </p><p> - Conceptually, configuration of a Yocto Project kernel occurs similarly to that needed for any - Linux kernel. - The build process for a Yocto Project kernel uses a <code class="filename">.config</code> file, which - is created through the Linux Kernel Coinfiguration (LKC) tool. - You can directly set various configurations in the - <code class="filename">.config</code> file by using the <code class="filename">menuconfig</code> - tool as built by BitBake. - You can also define configurations in the file by using configuration fragments. - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3> - It is not recommended that you edit the <code class="filename">.config</code> file directly. - </div><p> - Here are some brief descriptions of the ways you can affect the - <code class="filename">.config</code> file: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><span class="emphasis"><em>The <code class="filename">menuconfig</code> Tool:</em></span> - One of many front-ends that allows you to define kernel configurations. - Some others are <code class="filename">make config</code>, - <code class="filename">make nconfig</code>, and <code class="filename">make gconfig</code>. - In the Yocto Project environment, you must use BitBake to build the - <code class="filename">menuconfig</code> tool before you can use it to define - configurations: - </p><pre class="literallayout"> - $ bitbake linux-yocto -c menuconfig - </pre><p> - After the tool is built, you can interact with it normally. - You can see how <code class="filename">menuconfig</code> is used to change a simple - kernel configuration in the - "<a class="link" href="#changing-the-config-smp-configuration-using-menuconfig" target="_top">Changing the <code class="filename">CONFIG_SMP</code> Configuration Using <code class="filename">menuconfig</code></a>" - section of the Yocto Project Development Manual. - For general information on <code class="filename">menuconfig</code>, see - <a class="ulink" href="http://en.wikipedia.org/wiki/Menuconfig" target="_top">http://en.wikipedia.org/wiki/Menuconfig</a>. - </p></li><li class="listitem"><p><span class="emphasis"><em>Configuration Fragments:</em></span> A file with a - list of kernel options just as they would appear syntactically in the - <code class="filename">.config</code> file. - Configuration fragments are typically logical groupings and are assembled - by the OpenEmbedded build system to produce input used by the LKC - that ultimately generates the <code class="filename">.config</code> file.</p><p>The - <code class="filename"><a class="link" href="#var-KERNEL_FEATURES" target="_top">KERNEL_FEATURES</a></code> - variable can be used to list configuration fragments. - For further discussion on applying configuration fragments, see the - "<a class="link" href="#bsp-filelayout-kernel" target="_top">Linux Kernel Configuration</a>" - section in the Yocto Project Board Support Package (BSP) Guide. - </p></li></ul></div><p> - </p></div><div class="section" title="2.6. Kernel Tools"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="kernel-tools"></a>2.6. Kernel Tools</h2></div></div></div><p> - Since most standard workflows involve moving forward with an existing tree by - continuing to add and alter the underlying baseline, the tools that manage - the Yocto Project's kernel construction are largely hidden from the developer to - present a simplified view of the kernel for ease of use. - </p><p> - Fundamentally, the kernel tools that manage and construct the - Yocto Project kernel accomplish the following: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>Group patches into named, reusable features.</p></li><li class="listitem"><p>Allow top-down control of included features.</p></li><li class="listitem"><p>Bind kernel configurations to kernel patches and features.</p></li><li class="listitem"><p>Present a seamless Git repository that blends Yocto Project value - with the <code class="filename">kernel.org</code> history and development.</p></li></ul></div><p> - </p></div></div> - - <div class="chapter" title="Chapter 3. Working with the Yocto Project Kernel"><div class="titlepage"><div><div><h2 class="title"><a id="kernel-how-to"></a>Chapter 3. Working with the Yocto Project Kernel</h2></div></div></div><div class="toc"><dl><dt><span class="section"><a href="#actions-org">3.1. Introduction</a></span></dt><dt><span class="section"><a href="#tree-construction">3.2. Tree Construction</a></span></dt><dt><span class="section"><a href="#build-strategy">3.3. Build Strategy</a></span></dt><dt><span class="section"><a href="#workflow-examples">3.4. Workflow Examples</a></span></dt><dd><dl><dt><span class="section"><a href="#change-inspection-kernel-changes-commits">3.4.1. Change Inspection: Changes/Commits</a></span></dt><dt><span class="section"><a href="#development-saving-kernel-modifications">3.4.2. Development: Saving Kernel Modifications</a></span></dt><dt><span class="section"><a href="#scm-working-with-the-yocto-project-kernel-in-another-scm">3.4.3. Working with the Yocto Project Kernel in Another SCM</a></span></dt><dt><span class="section"><a href="#bsp-creating">3.4.4. Creating a BSP Based on an Existing Similar BSP</a></span></dt><dt><span class="section"><a href="#tip-dirty-string">3.4.5. "-dirty" String</a></span></dt></dl></dd></dl></div><div class="section" title="3.1. Introduction"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="actions-org"></a>3.1. Introduction</h2></div></div></div><p> - This chapter describes how to accomplish tasks involving a kernel's tree structure. - The information is designed to help the developer that wants to modify the Yocto - Project kernel and contribute changes upstream to the Yocto Project. - The information covers the following: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>Tree construction</p></li><li class="listitem"><p>Build strategies</p></li><li class="listitem"><p>Workflow examples</p></li></ul></div><p> - </p></div><div class="section" title="3.2. Tree Construction"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="tree-construction"></a>3.2. Tree Construction</h2></div></div></div><p> - This section describes construction of the Yocto Project kernel source repositories - as accomplished by the Yocto Project team to create kernel repositories. - These kernel repositories are found under the heading "Yocto Linux Kernel" at - <a class="ulink" href="http://git.yoctoproject.org/cgit.cgi" target="_top">http://git.yoctoproject.org/cgit.cgi</a> - and can be shipped as part of a Yocto Project release. - The team creates these repositories by - compiling and executing the set of feature descriptions for every BSP/feature - in the product. - Those feature descriptions list all necessary patches, - configuration, branching, tagging and feature divisions found in a kernel. - Thus, the Yocto Project kernel repository (or tree) is built. - </p><p> - The existence of this tree allows you to access and clone a particular - Yocto Project kernel repository and use it to build images based on their configurations - and features. - </p><p> - You can find the files used to describe all the valid features and BSPs - in the Yocto Project kernel in any clone of the Yocto Project kernel source repository - Git tree. - For example, the following command clones the Yocto Project baseline kernel that - branched off of <code class="filename">linux.org</code> version 3.4: - </p><pre class="literallayout"> - $ git clone git://git.yoctoproject.org/linux-yocto-3.4 - </pre><p> - For another example of how to set up a local Git repository of the Yocto Project - kernel files, see the - "<a class="link" href="#local-kernel-files" target="_top">Yocto Project Kernel</a>" bulleted - item in the Yocto Project Development Manual. - </p><p> - Once you have cloned the kernel Git repository on your local machine, you can - switch to the <code class="filename">meta</code> branch within the repository. - Here is an example that assumes the local Git repository for the kernel is in - a top-level directory named <code class="filename">linux-yocto-3.4</code>: - </p><pre class="literallayout"> - $ cd ~/linux-yocto-3.4 - $ git checkout -b meta origin/meta - </pre><p> - Once you have checked out and switched to the <code class="filename">meta</code> branch, - you can see a snapshot of all the kernel configuration and feature descriptions that are - used to build that particular kernel repository. - These descriptions are in the form of <code class="filename">.scc</code> files. - </p><p> - You should realize, however, that browsing your local kernel repository - for feature descriptions and patches is not an effective way to determine what is in a - particular kernel branch. - Instead, you should use Git directly to discover the changes in a branch. - Using Git is an efficient and flexible way to inspect changes to the kernel. - For examples showing how to use Git to inspect kernel commits, see the following sections - in this chapter. - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3> - Ground up reconstruction of the complete kernel tree is an action only taken by the - Yocto Project team during an active development cycle. - When you create a clone of the kernel Git repository, you are simply making it - efficiently available for building and development. - </div><p> - </p><p> - The following steps describe what happens when the Yocto Project Team constructs - the Yocto Project kernel source Git repository (or tree) found at - <a class="ulink" href="http://git.yoctoproject.org/cgit.cgi" target="_top">http://git.yoctoproject.org/cgit.cgi</a> given the - introduction of a new top-level kernel feature or BSP. - These are the actions that effectively create the tree - that includes the new feature, patch or BSP: - </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>A top-level kernel feature is passed to the kernel build subsystem. - Normally, this feature is a BSP for a particular kernel type.</p></li><li class="listitem"><p>The file that describes the top-level feature is located by searching - these system directories: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>The in-tree kernel-cache directories, which are located - in <code class="filename">meta/cfg/kernel-cache</code></p></li><li class="listitem"><p>Areas pointed to by <code class="filename">SRC_URI</code> statements - found in recipes</p></li></ul></div><p> - For a typical build, the target of the search is a - feature description in an <code class="filename">.scc</code> file - whose name follows this format: - </p><pre class="literallayout"> - <bsp_name>-<kernel_type>.scc - </pre><p> - </p></li><li class="listitem"><p>Once located, the feature description is either compiled into a simple script - of actions, or into an existing equivalent script that is already part of the - shipped kernel.</p></li><li class="listitem"><p>Extra features are appended to the top-level feature description. - These features can come from the - <a class="link" href="#var-KERNEL_FEATURES" target="_top"><code class="filename">KERNEL_FEATURES</code></a> - variable in recipes.</p></li><li class="listitem"><p>Each extra feature is located, compiled and appended to the script - as described in step three.</p></li><li class="listitem"><p>The script is executed to produce a series of <code class="filename">meta-*</code> - directories. - These directories are descriptions of all the branches, tags, patches and configurations that - need to be applied to the base Git repository to completely create the - source (build) branch for the new BSP or feature.</p></li><li class="listitem"><p>The base repository is cloned, and the actions - listed in the <code class="filename">meta-*</code> directories are applied to the - tree.</p></li><li class="listitem"><p>The Git repository is left with the desired branch checked out and any - required branching, patching and tagging has been performed.</p></li></ol></div><p> - </p><p> - The kernel tree is now ready for developer consumption to be locally cloned, - configured, and built into a Yocto Project kernel specific to some target hardware. - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>The generated <code class="filename">meta-*</code> directories add to the kernel - as shipped with the Yocto Project release. - Any add-ons and configuration data are applied to the end of an existing branch. - The full repository generation that is found in the - official Yocto Project kernel repositories at - <a class="ulink" href="http://git.yoctoproject.org/cgit.cgi" target="_top">http://git.yoctoproject.org/cgit.cgi</a> - is the combination of all supported boards and configurations.</p><p>The technique the Yocto Project team uses is flexible and allows for seamless - blending of an immutable history with additional patches specific to a - deployment. - Any additions to the kernel become an integrated part of the branches.</p></div><p> - </p></div><div class="section" title="3.3. Build Strategy"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="build-strategy"></a>3.3. Build Strategy</h2></div></div></div><p> - Once a local Git repository of the Yocto Project kernel exists on a development system, - you can consider the compilation phase of kernel development - building a kernel image. - Some prerequisites exist that are validated by the build process before compilation - starts: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>The <code class="filename">SRC_URI</code> points to the kernel Git - repository.</p></li><li class="listitem"><p>A BSP build branch exists. - This branch has the following form: - </p><pre class="literallayout"> - <kernel_type>/<bsp_name> - </pre></li></ul></div><p> - The OpenEmbedded build system makes sure these conditions exist before attempting compilation. - Other means, however, do exist, such as as bootstrapping a BSP, see - the "<a class="link" href="#workflow-examples" title="3.4. Workflow Examples">Workflow Examples</a>". - </p><p> - Before building a kernel, the build process verifies the tree - and configures the kernel by processing all of the - configuration "fragments" specified by feature descriptions in the <code class="filename">.scc</code> - files. - As the features are compiled, associated kernel configuration fragments are noted - and recorded in the <code class="filename">meta-*</code> series of directories in their compilation order. - The fragments are migrated, pre-processed and passed to the Linux Kernel - Configuration subsystem (<code class="filename">lkc</code>) as raw input in the form - of a <code class="filename">.config</code> file. - The <code class="filename">lkc</code> uses its own internal dependency constraints to do the final - processing of that information and generates the final <code class="filename">.config</code> file - that is used during compilation. - </p><p> - Using the board's architecture and other relevant values from the board's template, - kernel compilation is started and a kernel image is produced. - </p><p> - The other thing that you notice once you configure a kernel is that - the build process generates a build tree that is separate from your kernel's local Git - source repository tree. - This build tree has a name that uses the following form, where - <code class="filename">${MACHINE}</code> is the metadata name of the machine (BSP) and "kernel_type" is one - of the Yocto Project supported kernel types (e.g. "standard"): - </p><pre class="literallayout"> - linux-${MACHINE}-<kernel_type>-build - </pre><p> - </p><p> - The existing support in the <code class="filename">kernel.org</code> tree achieves this - default functionality. - </p><p> - This behavior means that all the generated files for a particular machine or BSP are now in - the build tree directory. - The files include the final <code class="filename">.config</code> file, all the <code class="filename">.o</code> - files, the <code class="filename">.a</code> files, and so forth. - Since each machine or BSP has its own separate build directory in its own separate branch - of the Git repository, you can easily switch between different builds. - </p></div><div class="section" title="3.4. Workflow Examples"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="workflow-examples"></a>3.4. Workflow Examples</h2></div></div></div><p> - As previously noted, the Yocto Project kernel has built-in Git integration. - However, these utilities are not the only way to work with the kernel repository. - The Yocto Project has not made changes to Git or to other tools that - would invalidate alternate workflows. - Additionally, the way the kernel repository is constructed results in using - only core Git functionality, thus allowing any number of tools or front ends to use the - resulting tree. - </p><p> - This section contains several workflow examples. - Many of the examples use Git commands. - You can find Git documentation at - <a class="ulink" href="http://git-scm.com/documentation" target="_top">http://git-scm.com/documentation</a>. - You can find a simple overview of using Git with the Yocto Project in the - "<a class="link" href="#git" target="_top">Git</a>" - section of the Yocto Project Development Manual. - </p><div class="section" title="3.4.1. Change Inspection: Changes/Commits"><div class="titlepage"><div><div><h3 class="title"><a id="change-inspection-kernel-changes-commits"></a>3.4.1. Change Inspection: Changes/Commits</h3></div></div></div><p> - A common question when working with a kernel is: - "What changes have been applied to this tree?" - </p><p> - In projects that have a collection of directories that - contain patches to the kernel, it is possible to inspect or "grep" the contents - of the directories to get a general feel for the changes. - This sort of patch inspection is not an efficient way to determine what has been - done to the kernel. - The reason it is inefficient is because there are many optional patches that are - selected based on the kernel type and the feature description. - Additionally, patches could exist in directories that are not included in the search. - </p><p> - A more efficient way to determine what has changed in the branch is to use - Git and inspect or search the kernel tree. - This method gives you a full view of not only the source code modifications, - but also provides the reasons for the changes. - </p><div class="section" title="3.4.1.1. What Changed in a Kernel?"><div class="titlepage"><div><div><h4 class="title"><a id="what-changed-in-a-kernel"></a>3.4.1.1. What Changed in a Kernel?</h4></div></div></div><p> - Following are a few examples that show how to use Git commands to examine changes. - Because Git repositories in the Yocto Project do not break existing Git - functionality, and because there exists many permutations of these types of - Git commands, many methods exist by which you can discover changes. - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3> - In the following examples, unless you provide a commit range, - <code class="filename">kernel.org</code> history is blended with Yocto Project - kernel changes. - You can form ranges by using branch names from the kernel tree as the - upper and lower commit markers with the Git commands. - You can see the branch names through the web interface to the - Yocto Project source repositories at - <a class="ulink" href="http://git.yoctoproject.org/cgit.cgi" target="_top">http://git.yoctoproject.org/cgit.cgi</a>. - For example, the branch names for the <code class="filename">linux-yocto-3.4</code> - kernel repository can be seen at - <a class="ulink" href="http://git.yoctoproject.org/cgit.cgi/linux-yocto-3.4/refs/heads" target="_top">http://git.yoctoproject.org/cgit.cgi/linux-yocto-3.4/refs/heads</a>. - </div><p> - To see a full range of the changes, use the - <code class="filename">git whatchanged</code> command and specify a commit range - for the branch (<code class="filename"><commit>..<commit></code>). - </p><p> - Here is an example that looks at what has changed in the - <code class="filename">emenlow</code> branch of the - <code class="filename">linux-yocto-3.4</code> kernel. - The lower commit range is the commit associated with the - <code class="filename">standard/base</code> branch, while - the upper commit range is the commit associated with the - <code class="filename">standard/emenlow</code> branch. - </p><pre class="literallayout"> - $ git whatchanged origin/standard/base..origin/standard/emenlow - </pre><p> - </p><p> - To see a summary of changes use the <code class="filename">git log</code> command. - Here is an example using the same branches: - </p><pre class="literallayout"> - $ git log --oneline origin/standard/base..origin/standard/emenlow - </pre><p> - The <code class="filename">git log</code> output might be more useful than - the <code class="filename">git whatchanged</code> as you get - a short, one-line summary of each change and not the entire commit. - </p><p> - If you want to see code differences associated with all the changes, use - the <code class="filename">git diff</code> command. - Here is an example: - </p><pre class="literallayout"> - $ git diff origin/standard/base..origin/standard/emenlow - </pre><p> - </p><p> - You can see the commit log messages and the text differences using the - <code class="filename">git show</code> command: - Here is an example: - </p><pre class="literallayout"> - $ git show origin/standard/base..origin/standard/emenlow - </pre><p> - </p><p> - You can create individual patches for each change by using the - <code class="filename">git format-patch</code> command. - Here is an example that that creates patch files for each commit and - places them in your <code class="filename">Documents</code> directory: - </p><pre class="literallayout"> - $ git format-patch -o $HOME/Documents origin/standard/base..origin/standard/emenlow - </pre><p> - </p></div><div class="section" title="3.4.1.2. Show a Particular Feature or Branch Change"><div class="titlepage"><div><div><h4 class="title"><a id="show-a-particular-feature-or-branch-change"></a>3.4.1.2. Show a Particular Feature or Branch Change</h4></div></div></div><p> - Developers use tags in the Yocto Project kernel tree to divide changes for significant - features or branches. - Once you know a particular tag, you can use Git commands - to show changes associated with the tag and find the branches that contain - the feature. - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3> - Because BSP branch, <code class="filename">kernel.org</code>, and feature tags are all - present, there could be many tags. - </div><p> - The <code class="filename">git show <tag></code> command shows changes that are tagged by - a feature. - Here is an example that shows changes tagged by the <code class="filename">systemtap</code> - feature: - </p><pre class="literallayout"> - $ git show systemtap - </pre><p> - You can use the <code class="filename">git branch --contains <tag></code> command - to show the branches that contain a particular feature. - This command shows the branches that contain the <code class="filename">systemtap</code> - feature: - </p><pre class="literallayout"> - $ git branch --contains systemtap - </pre><p> - </p><p> - You can use many other comparisons to isolate BSP and kernel changes. - For example, you can compare against <code class="filename">kernel.org</code> tags - such as the <code class="filename">v3.4</code> tag. - </p></div></div><div class="section" title="3.4.2. Development: Saving Kernel Modifications"><div class="titlepage"><div><div><h3 class="title"><a id="development-saving-kernel-modifications"></a>3.4.2. Development: Saving Kernel Modifications</h3></div></div></div><p> - Another common operation is to build a BSP supplied by the Yocto Project, make some - changes, rebuild, and then test. - Those local changes often need to be exported, shared or otherwise maintained. - </p><p> - Since the Yocto Project kernel source tree is backed by Git, this activity is - much easier as compared to with previous releases. - Because Git tracks file modifications, additions and deletions, it is easy - to modify the code and later realize that you need to save the changes. - It is also easy to determine what has changed. - This method also provides many tools to commit, undo and export those modifications. - </p><p> - This section and its sub-sections, describe general application of Git's - <code class="filename">push</code> and <code class="filename">pull</code> commands, which are used to - get your changes upstream or source your code from an upstream repository. - The Yocto Project provides scripts that help you work in a collaborative development - environment. - For information on these scripts, see the - "<a class="link" href="#pushing-a-change-upstream" target="_top">Using Scripts to Push a Change - Upstream and Request a Pull</a>" and - "<a class="link" href="#submitting-a-patch" target="_top">Using Email to Submit a Patch</a>" - sections in the Yocto Project Development Manual. - </p><p> - There are many ways to save kernel modifications. - The technique employed - depends on the destination for the patches: - - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>Bulk storage</p></li><li class="listitem"><p>Internal sharing either through patches or by using Git</p></li><li class="listitem"><p>External submissions</p></li><li class="listitem"><p>Exporting for integration into another Source Code - Manager (SCM)</p></li></ul></div><p> - </p><p> - Because of the following list of issues, the destination of the patches also influences - the method for gathering them: - - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>Bisectability</p></li><li class="listitem"><p>Commit headers</p></li><li class="listitem"><p>Division of subsystems for separate submission or review</p></li></ul></div><p> - </p><div class="section" title="3.4.2.1. Bulk Export"><div class="titlepage"><div><div><h4 class="title"><a id="bulk-export"></a>3.4.2.1. Bulk Export</h4></div></div></div><p> - This section describes how you can "bulk" export changes that have not - been separated or divided. - This situation works well when you are simply storing patches outside of the kernel - source repository, either permanently or temporarily, and you are not committing - incremental changes during development. - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3> - This technique is not appropriate for full integration of upstream submission - because changes are not properly divided and do not provide an avenue for per-change - commit messages. - Therefore, this example assumes that changes have not been committed incrementally - during development and that you simply must gather and export them. - </div><p> - </p><pre class="literallayout"> - # bulk export of ALL modifications without separation or division - # of the changes - - $ git add . - $ git commit -s -a -m <msg> - or - $ git commit -s -a # and interact with $EDITOR - </pre><p> - </p><p> - The previous operations capture all the local changes in the project source - tree in a single Git commit. - And, that commit is also stored in the project's source tree. - </p><p> - Once the changes are exported, you can restore them manually using a template - or through integration with the <code class="filename">default_kernel</code>. - </p></div><div class="section" title="3.4.2.2. Incremental/Planned Sharing"><div class="titlepage"><div><div><h4 class="title"><a id="incremental-planned-sharing"></a>3.4.2.2. Incremental/Planned Sharing</h4></div></div></div><p> - This section describes how to save modifications when you are making incremental - commits or practicing planned sharing. - The examples in this section assume that you have incrementally committed - changes to the tree during development and now need to export them. - The sections that follow - describe how you can export your changes internally through either patches or by - using Git commands. - </p><p> - During development, the following commands are of interest. - For full Git documentation, refer to the Git documentation at - <a class="ulink" href="http://github.com" target="_top">http://github.com</a>. - - </p><pre class="literallayout"> - # edit a file - $ vi <path>/file - # stage the change - $ git add <path>/file - # commit the change - $ git commit -s - # remove a file - $ git rm <path>/file - # commit the change - $ git commit -s - - ... etc. - </pre><p> - </p><p> - Distributed development with Git is possible when you use a universally - agreed-upon unique commit identifier (set by the creator of the commit) that maps to a - specific change set with a specific parent. - This identifier is created for you when - you create a commit, and is re-created when you amend, alter or re-apply - a commit. - As an individual in isolation, this is of no interest. - However, if you - intend to share your tree with normal Git <code class="filename">push</code> and - <code class="filename">pull</code> operations for - distributed development, you should consider the ramifications of changing a - commit that you have already shared with others. - </p><p> - Assuming that the changes have not been pushed upstream, or pulled into - another repository, you can update both the commit content and commit messages - associated with development by using the following commands: - - </p><pre class="literallayout"> - $ Git add <path>/file - $ Git commit --amend - $ Git rebase or Git rebase -i - </pre><p> - </p><p> - Again, assuming that the changes have not been pushed upstream, and that - no pending works-in-progress exist (use <code class="filename">git status</code> to check), then - you can revert (undo) commits by using the following commands: - - </p><pre class="literallayout"> - # remove the commit, update working tree and remove all - # traces of the change - $ git reset --hard HEAD^ - # remove the commit, but leave the files changed and staged for re-commit - $ git reset --soft HEAD^ - # remove the commit, leave file change, but not staged for commit - $ git reset --mixed HEAD^ - </pre><p> - </p><p> - You can create branches, "cherry-pick" changes, or perform any number of Git - operations until the commits are in good order for pushing upstream - or for pull requests. - After a <code class="filename">push</code> or <code class="filename">pull</code> command, - commits are normally considered - "permanent" and you should not modify them. - If the commits need to be changed, you can incrementally do so with new commits. - These practices follow standard Git workflow and the <code class="filename">kernel.org</code> best - practices, which is recommended. - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3> - It is recommended to tag or branch before adding changes to a Yocto Project - BSP or before creating a new one. - The reason for this recommendation is because the branch or tag provides a - reference point to facilitate locating and exporting local changes. - </div><p> - </p><div class="section" title="3.4.2.2.1. Exporting Changes Internally by Using Patches"><div class="titlepage"><div><div><h5 class="title"><a id="export-internally-via-patches"></a>3.4.2.2.1. Exporting Changes Internally by Using Patches</h5></div></div></div><p> - This section describes how you can extract committed changes from a working directory - by exporting them as patches. - Once the changes have been extracted, you can use the patches for upstream submission, - place them in a Yocto Project template for automatic kernel patching, - or apply them in many other common uses. - </p><p> - This example shows how to create a directory with sequentially numbered patches. - Once the directory is created, you can apply it to a repository using the - <code class="filename">git am</code> command to reproduce the original commit and all - the related information such as author, date, commit log, and so forth. - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3> - The new commit identifiers (ID) will be generated upon re-application. - This action reflects that the commit is now applied to an underlying commit - with a different ID. - </div><p> - </p><pre class="literallayout"> - # <first-commit> can be a tag if one was created before development - # began. It can also be the parent branch if a branch was created - # before development began. - - $ git format-patch -o <dir> <first commit>..<last commit> - </pre><p> - </p><p> - In other words: - </p><pre class="literallayout"> - # Identify commits of interest. - - # If the tree was tagged before development - $ git format-patch -o <save dir> <tag> - - # If no tags are available - $ git format-patch -o <save dir> HEAD^ # last commit - $ git format-patch -o <save dir> HEAD^^ # last 2 commits - $ git whatchanged # identify last commit - $ git format-patch -o <save dir> <commit id> - $ git format-patch -o <save dir> <rev-list> - </pre><p> - </p></div><div class="section" title="3.4.2.2.2. Exporting Changes Internally by Using Git"><div class="titlepage"><div><div><h5 class="title"><a id="export-internally-via-git"></a>3.4.2.2.2. Exporting Changes Internally by Using Git</h5></div></div></div><p> - This section describes how you can export changes from a working directory - by pushing the changes into a master repository or by making a pull request. - Once you have pushed the changes to the master repository, you can then - pull those same changes into a new kernel build at a later time. - </p><p> - Use this command form to push the changes: - </p><pre class="literallayout"> - $ git push ssh://<master_server>/<path_to_repo> - <local_branch>:<remote_branch> - </pre><p> - </p><p> - For example, the following command pushes the changes from your local branch - <code class="filename">yocto/standard/common-pc/base</code> to the remote branch with the same name - in the master repository <code class="filename">//git.mycompany.com/pub/git/kernel-3.4</code>. - </p><pre class="literallayout"> - $ git push ssh://git.mycompany.com/pub/git/kernel-3.4 \ - yocto/standard/common-pc/base:yocto/standard/common-pc/base - </pre><p> - </p><p> - A pull request entails using the <code class="filename">git request-pull</code> command to compose - an email to the - maintainer requesting that a branch be pulled into the master repository, see - <a class="ulink" href="http://github.com/guides/pull-requests" target="_top">http://github.com/guides/pull-requests</a> for an example. - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3> - Other commands such as <code class="filename">git stash</code> or branching can also be used to save - changes, but are not covered in this document. - </div><p> - </p></div></div><div class="section" title="3.4.2.3. Exporting Changes for External (Upstream) Submission"><div class="titlepage"><div><div><h4 class="title"><a id="export-for-external-upstream-submission"></a>3.4.2.3. Exporting Changes for External (Upstream) Submission</h4></div></div></div><p> - This section describes how to export changes for external upstream submission. - If the patch series is large or the maintainer prefers to pull - changes, you can submit these changes by using a pull request. - However, it is common to send patches as an email series. - This method allows easy review and integration of the changes. - </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3> - Before sending patches for review be sure you understand the - community standards for submitting and documenting changes and follow their best practices. - For example, kernel patches should follow standards such as: - <div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p> - <a class="ulink" href="http://linux.yyz.us/patch-format.html" target="_top">http://linux.yyz.us/patch-format.html</a></p></li><li class="listitem"><p>Documentation/SubmittingPatches (in any linux - kernel source tree)</p></li></ul></div></div><p> - </p><p> - The messages used to commit changes are a large part of these standards. - Consequently, be sure that the headers for each commit have the required information. - For information on how to follow the Yocto Project commit message standards, see the - "<a class="link" href="#how-to-submit-a-change" target="_top">How to Submit a - Change</a>" section in the Yocto Project Development Manual. - </p><p> - If the initial commits were not properly documented or do not meet those standards, - you can re-base by using the <code class="filename">git rebase -i</code> command to - manipulate the commits and - get them into the required format. - Other techniques such as branching and cherry-picking commits are also viable options. - </p><p> - Once you complete the commits, you can generate the email that sends the patches - to the maintainer(s) or lists that review and integrate changes. - The command <code class="filename">git send-email</code> is commonly used to ensure - that patches are properly - formatted for easy application and avoid mailer-induced patch damage. - </p><p> - The following is an example of dumping patches for external submission: - </p><pre class="literallayout"> - # dump the last 4 commits - $ git format-patch --thread -n -o ~/rr/ HEAD^^^^ - $ git send-email --compose --subject '[RFC 0/N] <patch series summary>' \ - --to foo@yoctoproject.org --to bar@yoctoproject.org \ - --cc list@yoctoproject.org ~/rr - # the editor is invoked for the 0/N patch, and when complete the entire - # series is sent via email for review - </pre><p> - </p></div><div class="section" title="3.4.2.4. Exporting Changes for Import into Another SCM"><div class="titlepage"><div><div><h4 class="title"><a id="export-for-import-into-other-scm"></a>3.4.2.4. Exporting Changes for Import into Another SCM</h4></div></div></div><p> - When you want to export changes for import into another - Source Code Manager (SCM), you can use any of the previously discussed - techniques. - However, if the patches are manually applied to a secondary tree and then - that tree is checked into the SCM, you can lose change information such as - commit logs. - This process is not recommended. - </p><p> - Many SCMs can directly import Git commits, or can translate Git patches so that - information is not lost. - Those facilities are SCM-dependent and you should use them whenever possible. - </p></div></div><div class="section" title="3.4.3. Working with the Yocto Project Kernel in Another SCM"><div class="titlepage"><div><div><h3 class="title"><a id="scm-working-with-the-yocto-project-kernel-in-another-scm"></a>3.4.3. Working with the Yocto Project Kernel in Another SCM</h3></div></div></div><p> - This section describes kernel development in an SCM other than Git, - which is not the same as exporting changes to another SCM described earlier. - For this scenario, you use the OpenEmbedded build system to - develop the kernel in a different SCM. - The following must be true for you to accomplish this: - </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>The delivered Yocto Project kernel must be exported into the second - SCM.</p></li><li class="listitem"><p>Development must be exported from that secondary SCM into a - format that can be used by the OpenEmbedded build system.</p></li></ul></div><p> - </p><div class="section" title="3.4.3.1. Exporting the Delivered Kernel to the SCM"><div class="titlepage"><div><div><h4 class="title"><a id="exporting-delivered-kernel-to-scm"></a>3.4.3.1. Exporting the Delivered Kernel to the SCM</h4></div></div></div><p> - Depending on the SCM, it might be possible to export the entire Yocto Project - kernel Git repository, branches and all, into a new environment. - This method is preferred because it has the most flexibility and potential to maintain - the meta data associated with each commit. - </p><p> - When a direct import mechanism is not available, it is still possible to - export a branch (or series of branches) and check them into a new repository. - </p><p> - The following commands illustrate some of the steps you could use to - import the <code class="filename">yocto/standard/common-pc/base</code> - kernel into a secondary SCM: - </p><pre class="literallayout"> - $ git checkout yocto/standard/common-pc/base - $ cd .. ; echo linux/.git > .cvsignore - $ cvs import -m "initial import" linux MY_COMPANY start - </pre><p> - </p><p> - You could now relocate the CVS repository and use it in a centralized manner. - </p><p> - The following commands illustrate how you can condense and merge two BSPs into a - second SCM: - </p><pre class="literallayout"> - $ git checkout yocto/standard/common-pc/base - $ git merge yocto/standard/common-pc-64/base - # resolve any conflicts and commit them - $ cd .. ; echo linux/.git > .cvsignore - $ cvs import -m "initial import" linux MY_COMPANY start - </pre><p> - </p></div><div class="section" title="3.4.3.2. Importing Changes for the Build"><div class="titlepage"><div><div><h4 class="title"><a id="importing-changes-for-build"></a>3.4.3.2. Importing Changes for the Build</h4></div></div></div><p> - Once development has reached a suitable point in the second development - environment, you need to export the changes as patches. - To export them, place the changes in a recipe and - automatically apply them to the kernel during patching. - </p></div></div><div class="section" title="3.4.4. Creating a BSP Based on an Existing Similar BSP"><div class="titlepage"><div><div><h3 class="title"><a id="bsp-creating"></a>3.4.4. Creating a BSP Based on an Existing Similar BSP</h3></div></div></div><p> - This section overviews the process of creating a BSP based on an - existing similar BSP. - The information is introductory in nature and does not provide step-by-step examples. - For detailed information on how to create a BSP given an existing similar BSP, see - the "<a class="link" href="#dev-manual-bsp-appendix" target="_top">BSP Development - Example</a>" appendix in the Yocto Project Development Manual, or see the - <a class="ulink" href="https://wiki.yoctoproject.org/wiki/Transcript:_creating_one_generic_Atom_BSP_from_another" target="_top">Transcript:_creating_one_generic_Atom_BSP_from_another</a> - wiki page. - </p><p> - The basic steps you need to follow are: - </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p><span class="emphasis"><em>Make sure you have set up a local source directory:</em></span> - You must create a local <a class="link" href="#source-directory" target="_top">source - directory</a> by either creating a Git repository (recommended) or - extracting a Yocto Project release tarball.</p></li><li class="listitem"><p><span class="emphasis"><em>Choose an existing BSP available with the Yocto Project:</em></span> - Try to map your board features as closely to the features of a BSP that is - already supported and exists in the Yocto Project. - Starting with something as close as possible to your board makes developing - your BSP easier. - You can find all the BSPs that are supported and ship with the Yocto Project - on the Yocto Project's Download page at - <a class="ulink" href="http://www.yoctoproject.org/download" target="_top">http://www.yoctoproject.org/download</a>.</p></li><li class="listitem"><p><span class="emphasis"><em>Be sure you have the Base BSP:</em></span> - You need to either have a local Git repository of the base BSP set up or - have downloaded and extracted the files from a release BSP tarball. - Either method gives you access to the BSP source files.</p></li><li class="listitem"><p><span class="emphasis"><em>Make a copy of the existing BSP, thus isolating your new - BSP work:</em></span> - Copying the existing BSP file structure gives you a new area in which to work.</p></li><li class="listitem"><p><span class="emphasis"><em>Make configuration and recipe changes to your new BSP:</em></span> - Configuration changes involve the files in the BSP's <code class="filename">conf</code> - directory. - Changes include creating a machine-specific configuration file and editing the - <code class="filename">layer.conf</code> file. - The configuration changes identify the kernel you will be using. - Recipe changes include removing, modifying, or adding new recipe files that - instruct the build process on what features to include in the image.</p></li><li class="listitem"><p><span class="emphasis"><em>Prepare for the build:</em></span> - Before you actually initiate the build, you need to set up the build environment - by sourcing the environment initialization script. - After setting up the environment, you need to make some build configuration - changes to the <code class="filename">local.conf</code> and <code class="filename">bblayers.conf</code> - files.</p></li><li class="listitem"><p><span class="emphasis"><em>Build the image:</em></span> - The OpenEmbedded build system uses BitBake to create the image. - You need to decide on the type of image you are going to build (e.g. minimal, base, - core, sato, and so forth) and then start the build using the <code class="filename">bitbake</code> - command.</p></li></ol></div><p> - </p></div><div class="section" title="3.4.5. "-dirty" String"><div class="titlepage"><div><div><h3 class="title"><a id="tip-dirty-string"></a>3.4.5. "-dirty" String</h3></div></div></div><p> - If kernel images are being built with "-dirty" on the end of the version - string, this simply means that modifications in the source - directory have not been committed. - </p><pre class="literallayout"> - $ git status - </pre><p> - </p><p> - You can use the above Git command to report modified, removed, or added files. - You should commit those changes to the tree regardless of whether they will be saved, - exported, or used. - Once you commit the changes you need to rebuild the kernel. - </p><p> - To brute force pickup and commit all such pending changes, enter the following: - </p><pre class="literallayout"> - $ git add . - $ git commit -s -a -m "getting rid of -dirty" - </pre><p> - </p><p> - Next, rebuild the kernel. - </p></div></div></div> - - - -</div> - -<table border="0" summary="manufactured viewport for HTML img" cellspacing="0" cellpadding="0" width="100%"><tr><td align="left"><img src="figures/poky-title.png" align="left" width="100%" /></td></tr></table> - - <div xml:lang="en" class="book" lang="en"><div class="titlepage"><div><div><h1 class="title"><a id="poky-ref-manual"></a></h1></div><div><div class="authorgroup"> - <div class="author"><h3 class="author"><span class="firstname">Richard</span> <span class="surname">Purdie</span></h3><div class="affiliation"> - <span class="orgname">Linux Foundation<br /></span> - </div><code class="email"><<a class="email" href="mailto:richard.purdie@linuxfoundation.org">richard.purdie@linuxfoundation.org</a>></code></div> - - </div></div><div><p class="copyright">Copyright © 2010-2012 Linux Foundation</p></div><div><div class="legalnotice" title="Legal Notice"><a id="id1506919"></a> - <p> - Permission is granted to copy, distribute and/or modify this document under - the terms of the <a class="ulink" href="http://creativecommons.org/licenses/by-sa/2.0/uk/" target="_top">Creative Commons Attribution-Share Alike 2.0 UK: England & Wales</a> as published by Creative Commons. - </p> - <div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3> - Due to production processes, there could be differences between the Yocto Project - documentation bundled in the release tarball and the - Yocto Project Reference Manual on - the <a class="ulink" href="http://www.yoctoproject.org" target="_top">Yocto Project</a> website. - For the latest version of this manual, see the manual on the website. - </div> - </div></div><div><div class="revhistory"><table border="1" width="100%" summary="Revision history"><tr><th align="left" valign="top" colspan="2"><b>Revision History</b></th></tr> - <tr><td align="left">Revision 4.0+git</td><td align="left">24 November 2010</td></tr><tr><td align="left" colspan="2">Released with the Yocto Project 0.9 Release</td></tr> - <tr><td align="left">Revision 1.0</td><td align="left">6 April 2011</td></tr><tr><td align="left" colspan="2">Released with the Yocto Project 1.0 Release.</td></tr> - <tr><td align="left">Revision 1.0.1</td><td align="left">23 May 2011</td></tr><tr><td align="left" colspan="2">Released with the Yocto Project 1.0.1 Release.</td></tr> - <tr><td align="left">Revision 1.1</td><td align="left">6 October 2011</td></tr><tr><td align="left" colspan="2">Released with the Yocto Project 1.1 Release.</td></tr> - <tr><td align="left">Revision 1.2</td><td align="left">April 2012</td></tr><tr><td align="left" colspan="2">Released with the Yocto Project 1.2 Release.</td></tr> - <tr><td align="left">Revision 1.3</td><td align="lef |