summaryrefslogtreecommitdiffstats
path: root/documentation/ref-manual/tasks.rst
blob: 9fe1c296aa9c3a2ed3872a1d622aec77d8bb2ee1 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
.. SPDX-License-Identifier: CC-BY-SA-2.0-UK

*****
Tasks
*****

Tasks are units of execution for BitBake. Recipes (``.bb`` files) use
tasks to complete configuring, compiling, and packaging software. This
chapter provides a reference of the tasks defined in the OpenEmbedded
build system.

Normal Recipe Build Tasks
=========================

The following sections describe normal tasks associated with building a
recipe. For more information on tasks and dependencies, see the
":ref:`Tasks <bitbake:bitbake-user-manual/bitbake-user-manual-metadata:tasks>`" and
":ref:`Dependencies <bitbake:bitbake-user-manual/bitbake-user-manual-execution:dependencies>`" sections in the
BitBake User Manual.

.. _ref-tasks-build:

``do_build``
------------

The default task for all recipes. This task depends on all other normal
tasks required to build a recipe.

.. _ref-tasks-compile:

``do_compile``
--------------

Compiles the source code. This task runs with the current working
directory set to ``${``\ :term:`B`\ ``}``.

The default behavior of this task is to run the ``oe_runmake`` function
if a makefile (``Makefile``, ``makefile``, or ``GNUmakefile``) is found.
If no such file is found, the ``do_compile`` task does nothing.

.. _ref-tasks-compile_ptest_base:

``do_compile_ptest_base``
-------------------------

Compiles the runtime test suite included in the software being built.

.. _ref-tasks-configure:

``do_configure``
----------------

Configures the source by enabling and disabling any build-time and
configuration options for the software being built. The task runs with
the current working directory set to ``${``\ :term:`B`\ ``}``.

The default behavior of this task is to run ``oe_runmake clean`` if a
makefile (``Makefile``, ``makefile``, or ``GNUmakefile``) is found and
:term:`CLEANBROKEN` is not set to "1". If no such
file is found or the ``CLEANBROKEN`` variable is set to "1", the
``do_configure`` task does nothing.

.. _ref-tasks-configure_ptest_base:

``do_configure_ptest_base``
---------------------------

Configures the runtime test suite included in the software being built.

.. _ref-tasks-deploy:

``do_deploy``
-------------

Writes output files that are to be deployed to
``${``\ :term:`DEPLOY_DIR_IMAGE`\ ``}``. The
task runs with the current working directory set to
``${``\ :term:`B`\ ``}``.

Recipes implementing this task should inherit the
:ref:`deploy <ref-classes-deploy>` class and should write the output
to ``${``\ :term:`DEPLOYDIR`\ ``}``, which is not to be
confused with ``${DEPLOY_DIR}``. The ``deploy`` class sets up
``do_deploy`` as a shared state (sstate) task that can be accelerated
through sstate use. The sstate mechanism takes care of copying the
output from ``${DEPLOYDIR}`` to ``${DEPLOY_DIR_IMAGE}``.

.. note::

   Do not write the output directly to ``${DEPLOY_DIR_IMAGE}``, as this causes
   the sstate mechanism to malfunction.

The ``do_deploy`` task is not added as a task by default and
consequently needs to be added manually. If you want the task to run
after :ref:`ref-tasks-compile`, you can add it by doing
the following:
::

      addtask deploy after do_compile

Adding ``do_deploy`` after other tasks works the same way.

.. note::

   You do not need to add ``before do_build`` to the ``addtask`` command
   (though it is harmless), because the ``base`` class contains the following:
   ::

           do_build[recrdeptask] += "do_deploy"


   See the ":ref:`bitbake-user-manual/bitbake-user-manual-execution:dependencies`"
   section in the BitBake User Manual for more information.

If the ``do_deploy`` task re-executes, any previous output is removed
(i.e. "cleaned").

.. _ref-tasks-fetch:

``do_fetch``
------------

Fetches the source code. This task uses the
:term:`SRC_URI` variable and the argument's prefix to
determine the correct :ref:`fetcher <bitbake:bitbake-user-manual/bitbake-user-manual-fetching:fetchers>`
module.

.. _ref-tasks-image:

``do_image``
------------

Starts the image generation process. The ``do_image`` task runs after
the OpenEmbedded build system has run the
:ref:`ref-tasks-rootfs` task during which packages are
identified for installation into the image and the root filesystem is
created, complete with post-processing.

The ``do_image`` task performs pre-processing on the image through the
:term:`IMAGE_PREPROCESS_COMMAND` and
dynamically generates supporting ``do_image_*`` tasks as needed.

For more information on image creation, see the ":ref:`overview-manual/concepts:image generation`"
section in the Yocto Project Overview and Concepts Manual.

.. _ref-tasks-image-complete:

``do_image_complete``
---------------------

Completes the image generation process. The ``do_image_complete`` task
runs after the OpenEmbedded build system has run the
:ref:`ref-tasks-image` task during which image
pre-processing occurs and through dynamically generated ``do_image_*``
tasks the image is constructed.

The ``do_image_complete`` task performs post-processing on the image
through the
:term:`IMAGE_POSTPROCESS_COMMAND`.

For more information on image creation, see the
":ref:`overview-manual/concepts:image generation`"
section in the Yocto Project Overview and Concepts Manual.

.. _ref-tasks-install:

``do_install``
--------------

Copies files that are to be packaged into the holding area
``${``\ :term:`D`\ ``}``. This task runs with the current
working directory set to ``${``\ :term:`B`\ ``}``, which is the
compilation directory. The ``do_install`` task, as well as other tasks
that either directly or indirectly depend on the installed files (e.g.
:ref:`ref-tasks-package`, ``do_package_write_*``, and
:ref:`ref-tasks-rootfs`), run under
:ref:`fakeroot <overview-manual/concepts:fakeroot and pseudo>`.

.. note::

   When installing files, be careful not to set the owner and group IDs
   of the installed files to unintended values. Some methods of copying
   files, notably when using the recursive ``cp`` command, can preserve
   the UID and/or GID of the original file, which is usually not what
   you want. The ``host-user-contaminated`` QA check checks for files
   that probably have the wrong ownership.

   Safe methods for installing files include the following:

   -  The ``install`` utility. This utility is the preferred method.

   -  The ``cp`` command with the "--no-preserve=ownership" option.

   -  The ``tar`` command with the "--no-same-owner" option. See the
      ``bin_package.bbclass`` file in the ``meta/classes`` directory of
      the :term:`Source Directory` for an example.

.. _ref-tasks-install_ptest_base:

``do_install_ptest_base``
-------------------------

Copies the runtime test suite files from the compilation directory to a
holding area.

.. _ref-tasks-package:

``do_package``
--------------

Analyzes the content of the holding area
``${``\ :term:`D`\ ``}`` and splits the content into subsets
based on available packages and files. This task makes use of the
:term:`PACKAGES` and :term:`FILES`
variables.

The ``do_package`` task, in conjunction with the
:ref:`ref-tasks-packagedata` task, also saves some
important package metadata. For additional information, see the
:term:`PKGDESTWORK` variable and the
":ref:`overview-manual/concepts:automatically added runtime dependencies`"
section in the Yocto Project Overview and Concepts Manual.

.. _ref-tasks-package_qa:

``do_package_qa``
-----------------

Runs QA checks on packaged files. For more information on these checks,
see the :ref:`insane <ref-classes-insane>` class.

.. _ref-tasks-package_write_deb:

``do_package_write_deb``
------------------------

Creates Debian packages (i.e. ``*.deb`` files) and places them in the
``${``\ :term:`DEPLOY_DIR_DEB`\ ``}`` directory in
the package feeds area. For more information, see the
":ref:`overview-manual/concepts:package feeds`" section in
the Yocto Project Overview and Concepts Manual.

.. _ref-tasks-package_write_ipk:

``do_package_write_ipk``
------------------------

Creates IPK packages (i.e. ``*.ipk`` files) and places them in the
``${``\ :term:`DEPLOY_DIR_IPK`\ ``}`` directory in
the package feeds area. For more information, see the
":ref:`overview-manual/concepts:package feeds`" section in
the Yocto Project Overview and Concepts Manual.

.. _ref-tasks-package_write_rpm:

``do_package_write_rpm``
------------------------

Creates RPM packages (i.e. ``*.rpm`` files) and places them in the
``${``\ :term:`DEPLOY_DIR_RPM`\ ``}`` directory in
the package feeds area. For more information, see the
":ref:`overview-manual/concepts:package feeds`" section in
the Yocto Project Overview and Concepts Manual.

.. _ref-tasks-package_write_tar:

``do_package_write_tar``
------------------------

Creates tarballs and places them in the
``${``\ :term:`DEPLOY_DIR_TAR`\ ``}`` directory in
the package feeds area. For more information, see the
":ref:`overview-manual/concepts:package feeds`" section in
the Yocto Project Overview and Concepts Manual.

.. _ref-tasks-packagedata:

``do_packagedata``
------------------

Saves package metadata generated by the
:ref:`ref-tasks-package` task in
:term:`PKGDATA_DIR` to make it available globally.

.. _ref-tasks-patch:

``do_patch``
------------

Locates patch files and applies them to the source code.

After fetching and unpacking source files, the build system uses the
recipe's :term:`SRC_URI` statements
to locate and apply patch files to the source code.

.. note::

   The build system uses the :term:`FILESPATH` variable to determine the
   default set of directories when searching for patches.

Patch files, by default, are ``*.patch`` and ``*.diff`` files created
and kept in a subdirectory of the directory holding the recipe file. For
example, consider the
:yocto_git:`bluez5 </poky/tree/meta/recipes-connectivity/bluez5>`
recipe from the OE-Core layer (i.e. ``poky/meta``):
::

   poky/meta/recipes-connectivity/bluez5

This recipe has two patch files located here:
::

   poky/meta/recipes-connectivity/bluez5/bluez5

In the ``bluez5`` recipe, the ``SRC_URI`` statements point to the source
and patch files needed to build the package.

.. note::

   In the case for the ``bluez5_5.48.bb`` recipe, the ``SRC_URI`` statements
   are from an include file ``bluez5.inc``.

As mentioned earlier, the build system treats files whose file types are
``.patch`` and ``.diff`` as patch files. However, you can use the
"apply=yes" parameter with the ``SRC_URI`` statement to indicate any
file as a patch file:
::

   SRC_URI = " \
       git://path_to_repo/some_package \
       file://file;apply=yes \
       "

Conversely, if you have a directory full of patch files and you want to
exclude some so that the ``do_patch`` task does not apply them during
the patch phase, you can use the "apply=no" parameter with the
``SRC_URI`` statement:
::

   SRC_URI = " \
       git://path_to_repo/some_package \
       file://path_to_lots_of_patch_files \
       file://path_to_lots_of_patch_files/patch_file5;apply=no \
       "

In the
previous example, assuming all the files in the directory holding the
patch files end with either ``.patch`` or ``.diff``, every file would be
applied as a patch by default except for the ``patch_file5`` patch.

You can find out more about the patching process in the
":ref:`overview-manual/concepts:patching`" section in
the Yocto Project Overview and Concepts Manual and the
":ref:`dev-manual/common-tasks:patching code`" section in the
Yocto Project Development Tasks Manual.

.. _ref-tasks-populate_lic:

``do_populate_lic``
-------------------

Writes license information for the recipe that is collected later when
the image is constructed.

.. _ref-tasks-populate_sdk:

``do_populate_sdk``
-------------------

Creates the file and directory structure for an installable SDK. See the
":ref:`overview-manual/concepts:sdk generation`"
section in the Yocto Project Overview and Concepts Manual for more
information.

.. _ref-tasks-populate_sdk_ext:

``do_populate_sdk_ext``
-----------------------

Creates the file and directory structure for an installable extensible 
SDK (eSDK). See the ":ref:`overview-manual/concepts:sdk generation`"
section in the Yocto Project Overview and Concepts Manual for more
information.


.. _ref-tasks-populate_sysroot:

``do_populate_sysroot``
-----------------------

Stages (copies) a subset of the files installed by the
:ref:`ref-tasks-install` task into the appropriate
sysroot. For information on how to access these files from other
recipes, see the :term:`STAGING_DIR* <STAGING_DIR_HOST>` variables.
Directories that would typically not be needed by other recipes at build
time (e.g. ``/etc``) are not copied by default.

For information on what directories are copied by default, see the
:term:`SYSROOT_DIRS* <SYSROOT_DIRS>` variables. You can change
these variables inside your recipe if you need to make additional (or
fewer) directories available to other recipes at build time.

The ``do_populate_sysroot`` task is a shared state (sstate) task, which
means that the task can be accelerated through sstate use. Realize also
that if the task is re-executed, any previous output is removed (i.e.
"cleaned").

.. _ref-tasks-prepare_recipe_sysroot:

``do_prepare_recipe_sysroot``
-----------------------------

Installs the files into the individual recipe specific sysroots (i.e.
``recipe-sysroot`` and ``recipe-sysroot-native`` under
``${``\ :term:`WORKDIR`\ ``}`` based upon the
dependencies specified by :term:`DEPENDS`). See the
":ref:`staging <ref-classes-staging>`" class for more information.

.. _ref-tasks-rm_work:

``do_rm_work``
--------------

Removes work files after the OpenEmbedded build system has finished with
them. You can learn more by looking at the
":ref:`rm_work.bbclass <ref-classes-rm-work>`" section.

.. _ref-tasks-unpack:

``do_unpack``
-------------

Unpacks the source code into a working directory pointed to by
``${``\ :term:`WORKDIR`\ ``}``. The :term:`S`
variable also plays a role in where unpacked source files ultimately
reside. For more information on how source files are unpacked, see the
":ref:`overview-manual/concepts:source fetching`"
section in the Yocto Project Overview and Concepts Manual and also see
the ``WORKDIR`` and ``S`` variable descriptions.

Manually Called Tasks
=====================

These tasks are typically manually triggered (e.g. by using the
``bitbake -c`` command-line option):

.. _ref-tasks-checkpkg:

``do_checkpkg``
---------------

Provides information about the recipe including its upstream version and
status. The upstream version and status reveals whether or not a version
of the recipe exists upstream and a status of not updated, updated, or
unknown.

To check the upstream version and status of a recipe, use the following
devtool commands:
::

   $ devtool latest-version
   $ devtool check-upgrade-status

See the ":ref:`ref-manual/devtool-reference:\`\`devtool\`\` quick reference`"
chapter for more information on
``devtool``. See the ":ref:`devtool-checking-on-the-upgrade-status-of-a-recipe`"
section for information on checking the upgrade status of a recipe.

To build the ``checkpkg`` task, use the ``bitbake`` command with the
"-c" option and task name:
::

   $ bitbake core-image-minimal -c checkpkg

By default, the results are stored in :term:`$LOG_DIR <LOG_DIR>` (e.g.
``$BUILD_DIR/tmp/log``).

.. _ref-tasks-checkuri:

``do_checkuri``
---------------

Validates the :term:`SRC_URI` value.

.. _ref-tasks-clean:

``do_clean``
------------

Removes all output files for a target from the
:ref:`ref-tasks-unpack` task forward (i.e. ``do_unpack``,
:ref:`ref-tasks-configure`,
:ref:`ref-tasks-compile`,
:ref:`ref-tasks-install`, and
:ref:`ref-tasks-package`).

You can run this task using BitBake as follows:
::

   $ bitbake -c clean recipe

Running this task does not remove the
:ref:`sstate <overview-manual/concepts:shared state cache>` cache files.
Consequently, if no changes have been made and the recipe is rebuilt
after cleaning, output files are simply restored from the sstate cache.
If you want to remove the sstate cache files for the recipe, you need to
use the :ref:`ref-tasks-cleansstate` task instead
(i.e. ``bitbake -c cleansstate`` recipe).

.. _ref-tasks-cleanall:

``do_cleanall``
---------------

Removes all output files, shared state
(:ref:`sstate <overview-manual/concepts:shared state cache>`) cache, and
downloaded source files for a target (i.e. the contents of
:term:`DL_DIR`). Essentially, the ``do_cleanall`` task is
identical to the :ref:`ref-tasks-cleansstate` task
with the added removal of downloaded source files.

You can run this task using BitBake as follows:
::

   $ bitbake -c cleanall recipe

Typically, you would not normally use the ``cleanall`` task. Do so only
if you want to start fresh with the :ref:`ref-tasks-fetch`
task.

.. _ref-tasks-cleansstate:

``do_cleansstate``
------------------

Removes all output files and shared state
(:ref:`sstate <overview-manual/concepts:shared state cache>`) cache for a
target. Essentially, the ``do_cleansstate`` task is identical to the
:ref:`ref-tasks-clean` task with the added removal of
shared state (:ref:`sstate <overview-manual/concepts:shared state cache>`)
cache.

You can run this task using BitBake as follows:
::

   $ bitbake -c cleansstate recipe

When you run the ``do_cleansstate`` task, the OpenEmbedded build system
no longer uses any sstate. Consequently, building the recipe from
scratch is guaranteed.

.. note::

   The ``do_cleansstate`` task cannot remove sstate from a remote sstate
   mirror. If you need to build a target from scratch using remote mirrors, use
   the "-f" option as follows:
   ::

      $ bitbake -f -c do_cleansstate target


.. _ref-tasks-devpyshell:

``do_devpyshell``
-----------------

Starts a shell in which an interactive Python interpreter allows you to
interact with the BitBake build environment. From within this shell, you
can directly examine and set bits from the data store and execute
functions as if within the BitBake environment. See the ":ref:`dev-manual/common-tasks:using a development python shell`" section in
the Yocto Project Development Tasks Manual for more information about
using ``devpyshell``.

.. _ref-tasks-devshell:

``do_devshell``
---------------

Starts a shell whose environment is set up for development, debugging,
or both. See the ":ref:`dev-manual/common-tasks:using a development shell`" section in the
Yocto Project Development Tasks Manual for more information about using
``devshell``.

.. _ref-tasks-listtasks:

``do_listtasks``
----------------

Lists all defined tasks for a target.

.. _ref-tasks-package_index:

``do_package_index``
--------------------

Creates or updates the index in the :ref:`overview-manual/concepts:package feeds` area.

.. note::

   This task is not triggered with the ``bitbake -c`` command-line option as
   are the other tasks in this section. Because this task is specifically for
   the ``package-index`` recipe, you run it using ``bitbake package-index``.

Image-Related Tasks
===================

The following tasks are applicable to image recipes.

.. _ref-tasks-bootimg:

``do_bootimg``
--------------

Creates a bootable live image. See the
:term:`IMAGE_FSTYPES` variable for additional
information on live image types.

.. _ref-tasks-bundle_initramfs:

``do_bundle_initramfs``
-----------------------

Combines an initial RAM disk (initramfs) image and kernel together to
form a single image. The
:term:`CONFIG_INITRAMFS_SOURCE` variable
has some more information about these types of images.

.. _ref-tasks-rootfs:

``do_rootfs``
-------------

Creates the root filesystem (file and directory structure) for an image.
See the ":ref:`overview-manual/concepts:image generation`"
section in the Yocto Project Overview and Concepts Manual for more
information on how the root filesystem is created.

.. _ref-tasks-testimage:

``do_testimage``
----------------

Boots an image and performs runtime tests within the image. For
information on automatically testing images, see the
":ref:`dev-manual/common-tasks:performing automated runtime testing`"
section in the Yocto Project Development Tasks Manual.

.. _ref-tasks-testimage_auto:

``do_testimage_auto``
---------------------

Boots an image and performs runtime tests within the image immediately
after it has been built. This task is enabled when you set
:term:`TESTIMAGE_AUTO` equal to "1".

For information on automatically testing images, see the
":ref:`dev-manual/common-tasks:performing automated runtime testing`"
section in the Yocto Project Development Tasks Manual.

Kernel-Related Tasks
====================

The following tasks are applicable to kernel recipes. Some of these
tasks (e.g. the :ref:`ref-tasks-menuconfig` task) are
also applicable to recipes that use Linux kernel style configuration
such as the BusyBox recipe.

.. _ref-tasks-compile_kernelmodules:

``do_compile_kernelmodules``
----------------------------

Runs the step that builds the kernel modules (if needed). Building a
kernel consists of two steps: 1) the kernel (``vmlinux``) is built, and
2) the modules are built (i.e. ``make modules``).

.. _ref-tasks-diffconfig:

``do_diffconfig``
-----------------

When invoked by the user, this task creates a file containing the
differences between the original config as produced by
:ref:`ref-tasks-kernel_configme` task and the
changes made by the user with other methods (i.e. using
(:ref:`ref-tasks-kernel_menuconfig`). Once the
file of differences is created, it can be used to create a config
fragment that only contains the differences. You can invoke this task
from the command line as follows:
::

   $ bitbake linux-yocto -c diffconfig

For more information, see the
":ref:`kernel-dev/common:creating configuration fragments`"
section in the Yocto Project Linux Kernel Development Manual.

.. _ref-tasks-kernel_checkout:

``do_kernel_checkout``
----------------------

Converts the newly unpacked kernel source into a form with which the
OpenEmbedded build system can work. Because the kernel source can be
fetched in several different ways, the ``do_kernel_checkout`` task makes
sure that subsequent tasks are given a clean working tree copy of the
kernel with the correct branches checked out.

.. _ref-tasks-kernel_configcheck:

``do_kernel_configcheck``
-------------------------

Validates the configuration produced by the
:ref:`ref-tasks-kernel_menuconfig` task. The
``do_kernel_configcheck`` task produces warnings when a requested
configuration does not appear in the final ``.config`` file or when you
override a policy configuration in a hardware configuration fragment.
You can run this task explicitly and view the output by using the
following command:
::

   $ bitbake linux-yocto -c kernel_configcheck -f

For more information, see the
":ref:`kernel-dev/common:validating configuration`"
section in the Yocto Project Linux Kernel Development Manual.

.. _ref-tasks-kernel_configme:

``do_kernel_configme``
----------------------

After the kernel is patched by the :ref:`ref-tasks-patch`
task, the ``do_kernel_configme`` task assembles and merges all the
kernel config fragments into a merged configuration that can then be
passed to the kernel configuration phase proper. This is also the time
during which user-specified defconfigs are applied if present, and where
configuration modes such as ``--allnoconfig`` are applied.

.. _ref-tasks-kernel_menuconfig:

``do_kernel_menuconfig``
------------------------

Invoked by the user to manipulate the ``.config`` file used to build a
linux-yocto recipe. This task starts the Linux kernel configuration
tool, which you then use to modify the kernel configuration.

.. note::

   You can also invoke this tool from the command line as follows:
   ::

           $ bitbake linux-yocto -c menuconfig


See the ":ref:`kernel-dev/common:using \`\`menuconfig\`\``"
section in the Yocto Project Linux Kernel Development Manual for more
information on this configuration tool.

.. _ref-tasks-kernel_metadata:

``do_kernel_metadata``
----------------------

Collects all the features required for a given kernel build, whether the
features come from :term:`SRC_URI` or from Git
repositories. After collection, the ``do_kernel_metadata`` task
processes the features into a series of config fragments and patches,
which can then be applied by subsequent tasks such as
:ref:`ref-tasks-patch` and
:ref:`ref-tasks-kernel_configme`.

.. _ref-tasks-menuconfig:

``do_menuconfig``
-----------------

Runs ``make menuconfig`` for the kernel. For information on
``menuconfig``, see the
":ref:`kernel-dev/common:using \`\`menuconfig\`\``"
section in the Yocto Project Linux Kernel Development Manual.

.. _ref-tasks-savedefconfig:

``do_savedefconfig``
--------------------

When invoked by the user, creates a defconfig file that can be used
instead of the default defconfig. The saved defconfig contains the
differences between the default defconfig and the changes made by the
user using other methods (i.e. the
:ref:`ref-tasks-kernel_menuconfig` task. You
can invoke the task using the following command:
::

   $ bitbake linux-yocto -c savedefconfig

.. _ref-tasks-shared_workdir:

``do_shared_workdir``
---------------------

After the kernel has been compiled but before the kernel modules have
been compiled, this task copies files required for module builds and
which are generated from the kernel build into the shared work
directory. With these copies successfully copied, the
:ref:`ref-tasks-compile_kernelmodules` task
can successfully build the kernel modules in the next step of the build.

.. _ref-tasks-sizecheck:

``do_sizecheck``
----------------

After the kernel has been built, this task checks the size of the
stripped kernel image against
:term:`KERNEL_IMAGE_MAXSIZE`. If that
variable was set and the size of the stripped kernel exceeds that size,
the kernel build produces a warning to that effect.

.. _ref-tasks-strip:

``do_strip``
------------

If ``KERNEL_IMAGE_STRIP_EXTRA_SECTIONS`` is defined, this task strips
the sections named in that variable from ``vmlinux``. This stripping is
typically used to remove nonessential sections such as ``.comment``
sections from a size-sensitive configuration.

.. _ref-tasks-validate_branches:

``do_validate_branches``
------------------------

After the kernel is unpacked but before it is patched, this task makes
sure that the machine and metadata branches as specified by the
:term:`SRCREV` variables actually exist on the specified
branches. If these branches do not exist and
:term:`AUTOREV` is not being used, the
``do_validate_branches`` task fails during the build.