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authorScott Rifenbark <scott.m.rifenbark@intel.com>2012-08-27 07:19:12 -0700
committerRichard Purdie <richard.purdie@linuxfoundation.org>2012-09-04 12:55:01 +0100
commitd9b2ceeea3c8dc8d4437679621d8ee87cdc56b55 (patch)
tree702d5775c58d75d149cd4dff96a887d736cc693f
parente4bb6b7be871b2a205e5a42dc9c9b1a340c9c0b5 (diff)
downloadpoky-d9b2ceeea3c8dc8d4437679621d8ee87cdc56b55.tar.gz
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documentation/mega-manual: New mega-manual directory
This new directory contains the files for the mega-manual HTML document. Mega-manual is a compilation of all the existing YP manuals and guides. It is a single HTML file that simply lists each individual HTML document for the existing YP manuals and guides. The figures directory contains all the figures (duplicated) from the individual manuals and guides. (From yocto-docs rev: 5620c20ea4c7c69c96601b7480471e6166fd9409) Signed-off-by: Scott Rifenbark <scott.m.rifenbark@intel.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
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+<?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&amp;action=historysubmit&amp;diff=4309&amp;okdid=4225" target="_top">OE and Your Distro</a> and
+ <a class="ulink" href="http://www.openembedded.org/index.php?title=Required_software&amp;action=historysubmit&amp;diff=4311&amp;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-&lt;<span class="emphasis"><em>host_system</em></span>&gt;-&lt;<span class="emphasis"><em>arch</em></span>&gt;-toolchain-gmae-&lt;<span class="emphasis"><em>release</em></span>&gt;.tar.bz2
+
+ Where:
+ &lt;<span class="emphasis"><em>host_system</em></span>&gt; is a string representing your development system:
+ i686 or x86_64.
+
+ &lt;<span class="emphasis"><em>arch</em></span>&gt; is a string representing the target architecture:
+ i586, x86_64, powerpc, mips, or arm.
+
+ &lt;<span class="emphasis"><em>release</em></span>&gt; 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&lt;<span class="emphasis"><em>arch</em></span>&gt;.bin
+ vmlinux-qemu&lt;<span class="emphasis"><em>arch</em></span>&gt;.bin
+
+ Where:
+ &lt;<span class="emphasis"><em>arch</em></span>&gt; 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-&lt;<span class="emphasis"><em>profile</em></span>&gt;-qemu&lt;<span class="emphasis"><em>arch</em></span>&gt;.ext3
+ core-image-&lt;<span class="emphasis"><em>profile</em></span>&gt;-qemu&lt;<span class="emphasis"><em>arch</em></span>&gt;.tar.bz2
+
+ Where:
+ &lt;<span class="emphasis"><em>profile</em></span>&gt; 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.
+
+ &lt;<span class="emphasis"><em>arch</em></span>&gt; 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-&lt;<span class="emphasis"><em>arch</em></span>&gt;-poky-linux-&lt;<span class="emphasis"><em>if</em></span>&gt;
+
+ Where:
+ &lt;<span class="emphasis"><em>arch</em></span>&gt; is a string representing the target architecture:
+ i586, x86_64, ppc603e, mips, or armv5te.
+
+ &lt;<span class="emphasis"><em>if</em></span>&gt; 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 &lt;<span class="emphasis"><em>qemuarch</em></span>&gt; &lt;<span class="emphasis"><em>kernel-image</em></span>&gt; &lt;<span class="emphasis"><em>filesystem-image</em></span>&gt;
+
+ Where:
+ &lt;<span class="emphasis"><em>qemuarch</em></span>&gt; is a string representing the target architecture: qemux86, qemux86-64,
+ qemuppc, qemumips, or qemuarm.
+
+ &lt;<span class="emphasis"><em>kernel-image</em></span>&gt; is the architecture-specific kernel image.
+
+ &lt;<span class="emphasis"><em>filesystem-image</em></span>&gt; 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">&lt;<a class="email" href="mailto:scott.m.rifenbark@intel.com">scott.m.rifenbark@intel.com</a>&gt;</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 &amp; 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-&lt;BSP_name&gt;
+ </pre><p>
+ where &lt;BSP_name&gt; 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 &lt;branch-name&gt;</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 &lt;working-branch&gt;</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 &lt;branch-name&gt;</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 &lt;branch-name&gt;.</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 #&lt;bug-id&gt;]
+
+ &lt;detailed description of change&gt;
+ </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-&lt;layer_name&gt;</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 &lt;command&gt; [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/&lt;arch&gt;-poky-linux/linux-yocto-&lt;release-specific-string&gt;/linux-&lt;arch&gt;-&lt;build-type&gt;</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" &gt;&gt; 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-&lt;PN&gt; = "${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/&lt;host-arch&gt;/usr/bin/&lt;target-abi&gt;-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/&lt;target-abi&gt;/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/&lt;target-abi&gt;/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/&lt;target-abi&gt;/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">
+ $ &lt;target-abi&gt;-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/&lt;machine-name&gt;/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-&lt;release&gt;-&lt;date&gt;-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 -&gt; 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 ‘&lt;-m 256 -full-screen&gt;’
+ </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 -&gt; New -&gt; 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 -&gt; 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 -&gt; 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 -&gt; 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 -&gt; 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 -&gt; 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/&lt;programname&gt;</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 -&gt; Open Perspective -&gt; 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 -&gt; New -&gt; Project</code>.</p></li><li class="listitem"><p>Choose <code class="filename">LTTng -&gt; LTTng Project</code>.</p></li><li class="listitem"><p>Click <code class="filename">YoctoTools -&gt; 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 -&gt; Open Perspective -&gt; 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 -&gt; New -&gt; Project</code> to create a new Yocto
+ Bitbake Commander project.</p></li><li class="listitem"><p>Choose <code class="filename">Yocto Project Bitbake Commander -&gt; 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">&lt;project_location&gt;/&lt;project_name&gt;</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 -&gt; New -&gt; Yocto BitBake Commander -&gt; 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 -&gt; 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 &lt;name_of_package&gt;
+ </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 &lt;name_of_package&gt;
+ </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-&lt;name&gt;</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 &lt;target&gt;'
+
+ 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 &lt;target&gt;'
+
+ 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">&lt;<a class="email" href="mailto:jessica.zhang@intel.com">jessica.zhang@intel.com</a>&gt;</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 &amp; 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_&lt;arch&gt;</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_&lt;arch&gt;</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_&lt;arch&gt;</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_&lt;arch&gt;</code>
+ to "minimal sato-sdk", then <code class="filename">YOCTOADT_ROOTFS_&lt;arch&gt;</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_&lt;arch&gt;</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_&lt;arch&gt;</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">&lt;sysroot_dir&gt;</code>.
+ Finally, have an OPKG configuration file <code class="filename">&lt;conf_file&gt;</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 &lt;conf_file&gt; -o &lt;sysroot_dir&gt; update
+ $ opkg-cl –f &lt;cconf_file&gt; -o &lt;sysroot_dir&gt; \
+ --force-overwrite install libglade
+ $ opkg-cl –f &lt;cconf_file&gt; -o &lt;sysroot_dir&gt; \
+ --force-overwrite install libglade-dbg
+ $ opkg-cl –f &lt;conf_file&gt; -o &lt;sysroot_dir&gt; \
+ --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=&lt;sysroot-dir&gt;
+ </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=&lt;sysroot-dir&gt;</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 &lt;dir_containing_your_project-specific_m4_macros&gt;]
+ $ 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=”${CFLAGS} --sysroot=&lt;sysroot-dir&gt;”
+ CXXFLAGS=”${CXXFLAGS} --sysroot=&lt;sysroot-dir&gt;”
+ </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">&lt;<a class="email" href="mailto:tom.zanussi@intel.com">tom.zanussi@intel.com</a>&gt;</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">&lt;<a class="email" href="mailto:richard.purdie@linuxfoundation.org">richard.purdie@linuxfoundation.org</a>&gt;</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 &amp; 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-&lt;bsp_name&gt;
+ </pre><p>
+ "bsp_name" is a placeholder for the machine or platform name.
+ </p><p>
+ The layer's base directory (<code class="filename">meta-&lt;bsp_name&gt;</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-&lt;bsp_name&gt; \
+ "
+ </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-&lt;bsp_name&gt;/
+ meta-&lt;bsp_name&gt;/&lt;bsp_license_file&gt;
+ meta-&lt;bsp_name&gt;/README
+ meta-&lt;bsp_name&gt;/README.sources
+ meta-&lt;bsp_name&gt;/binary/&lt;bootable_images&gt;
+ meta-&lt;bsp_name&gt;/conf/layer.conf
+ meta-&lt;bsp_name&gt;/conf/machine/*.conf
+ meta-&lt;bsp_name&gt;/recipes-bsp/*
+ meta-&lt;bsp_name&gt;/recipes-core/*
+ meta-&lt;bsp_name&gt;/recipes-graphics/*
+ meta-&lt;bsp_name&gt;/recipes-kernel/linux/linux-yocto_&lt;kernel_rev&gt;.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-&lt;bsp_name&gt;/&lt;bsp_license_file&gt;
+ </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-&lt;bsp_name&gt;/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-&lt;bsp_name&gt;/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-&lt;bsp_name&gt;/binary/&lt;bootable_images&gt;
+ </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-&lt;bsp_name&gt;/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">&lt;bsp_name&gt;</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-&lt;bsp_name&gt;/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-&lt;bsp_name&gt;/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-&lt;bsp_name&gt;/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-&lt;bsp_name&gt;/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-&lt;bsp_name&gt;/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-&lt;bsp_name&gt;/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">&lt;bsp_name&gt;.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-&lt;bsp_name&gt;</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-&lt;bsp_name&gt;</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-&lt;bsp_name&gt;</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-&lt;bsp_name&gt;</code> directory.
+ This file identifies the <code class="filename">meta-&lt;bsp_name&gt;</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/&lt;bsp_name&gt;.conf</code>
+ in the <code class="filename">meta-&lt;bsp_name&gt;</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-&lt;bsp_name&gt;</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=&amp;download_type=1&amp;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 &lt;bsp-name&gt; &lt;karch&gt; [-o &lt;DIRNAME&gt; | --outdir &lt;DIRNAME&gt;]
+ [-i &lt;JSON PROPERTY FILE&gt; | --infile &lt;JSON PROPERTY_FILE&gt;]
+
+ 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 &lt;bsp-name&gt; &lt;karch&gt; [-o &lt;DIRNAME&gt; | --outdir &lt;DIRNAME&gt;]
+ [-i &lt;JSON PROPERTY FILE&gt; | --infile &lt;JSON PROPERTY_FILE&gt;]
+
+ 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 =&gt; [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">&lt;<a class="email" href="mailto:bruce.ashfield@windriver.com">bruce.ashfield@windriver.com</a>&gt;</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 &amp; 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">
+ &lt;bsp_name&gt;-&lt;kernel_type&gt;.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">
+ &lt;kernel_type&gt;/&lt;bsp_name&gt;
+ </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}-&lt;kernel_type&gt;-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">&lt;commit&gt;..&lt;commit&gt;</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 &lt;tag&gt;</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 &lt;tag&gt;</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 &lt;msg&gt;
+ 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 &lt;path&gt;/file
+ # stage the change
+ $ git add &lt;path&gt;/file
+ # commit the change
+ $ git commit -s
+ # remove a file
+ $ git rm &lt;path&gt;/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 &lt;path&gt;/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">
+ # &lt;first-commit&gt; 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 &lt;dir&gt; &lt;first commit&gt;..&lt;last commit&gt;
+ </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 &lt;save dir&gt; &lt;tag&gt;
+
+ # If no tags are available
+ $ git format-patch -o &lt;save dir&gt; HEAD^ # last commit
+ $ git format-patch -o &lt;save dir&gt; HEAD^^ # last 2 commits
+ $ git whatchanged # identify last commit
+ $ git format-patch -o &lt;save dir&gt; &lt;commit id&gt;
+ $ git format-patch -o &lt;save dir&gt; &lt;rev-list&gt;
+ </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://&lt;master_server&gt;/&lt;path_to_repo&gt;
+ &lt;local_branch&gt;:&lt;remote_branch&gt;
+ </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/Submitt