blob: 249b58e60caf5a74acf06615de721b5e41c2e269 [file] [log] [blame]
Andrew Geisslerf0343792020-11-18 10:42:21 -06001.. SPDX-License-Identifier: CC-BY-SA-2.0-UK
Andrew Geisslerc9f78652020-09-18 14:11:35 -05002
3*******
4Classes
5*******
6
7Class files are used to abstract common functionality and share it
8amongst multiple recipe (``.bb``) files. To use a class file, you simply
9make sure the recipe inherits the class. In most cases, when a recipe
10inherits a class it is enough to enable its features. There are cases,
11however, where in the recipe you might need to set variables or override
12some default behavior.
13
14Any :term:`Metadata` usually found in a recipe can also be
15placed in a class file. Class files are identified by the extension
16``.bbclass`` and are usually placed in a ``classes/`` directory beneath
17the ``meta*/`` directory found in the :term:`Source Directory`.
18Class files can also be pointed to by
19:term:`BUILDDIR` (e.g. ``build/``) in the same way as
20``.conf`` files in the ``conf`` directory. Class files are searched for
21in :term:`BBPATH` using the same method by which ``.conf``
22files are searched.
23
24This chapter discusses only the most useful and important classes. Other
25classes do exist within the ``meta/classes`` directory in the Source
26Directory. You can reference the ``.bbclass`` files directly for more
27information.
28
29.. _ref-classes-allarch:
30
31``allarch.bbclass``
32===================
33
34The ``allarch`` class is inherited by recipes that do not produce
35architecture-specific output. The class disables functionality that is
36normally needed for recipes that produce executable binaries (such as
37building the cross-compiler and a C library as pre-requisites, and
38splitting out of debug symbols during packaging).
39
40.. note::
41
42 Unlike some distro recipes (e.g. Debian), OpenEmbedded recipes that
43 produce packages that depend on tunings through use of the
44 :term:`RDEPENDS` and
45 :term:`TUNE_PKGARCH` variables, should never be
46 configured for all architectures using ``allarch``. This is the case
47 even if the recipes do not produce architecture-specific output.
48
49 Configuring such recipes for all architectures causes the
Andrew Geissler4c19ea12020-10-27 13:52:24 -050050 ``do_package_write_*`` tasks to
Andrew Geisslerc9f78652020-09-18 14:11:35 -050051 have different signatures for the machines with different tunings.
52 Additionally, unnecessary rebuilds occur every time an image for a
53 different ``MACHINE`` is built even when the recipe never changes.
54
55By default, all recipes inherit the :ref:`base <ref-classes-base>` and
56:ref:`package <ref-classes-package>` classes, which enable
57functionality needed for recipes that produce executable output. If your
58recipe, for example, only produces packages that contain configuration
59files, media files, or scripts (e.g. Python and Perl), then it should
60inherit the ``allarch`` class.
61
62.. _ref-classes-archiver:
63
64``archiver.bbclass``
65====================
66
67The ``archiver`` class supports releasing source code and other
68materials with the binaries.
69
70For more details on the source archiver, see the
71":ref:`dev-manual/dev-manual-common-tasks:maintaining open source license compliance during your product's lifecycle`"
72section in the Yocto Project Development Tasks Manual. You can also see
73the :term:`ARCHIVER_MODE` variable for information
74about the variable flags (varflags) that help control archive creation.
75
76.. _ref-classes-autotools:
77
78``autotools*.bbclass``
79======================
80
81The ``autotools*`` classes support Autotooled packages.
82
83The ``autoconf``, ``automake``, and ``libtool`` packages bring
84standardization. This class defines a set of tasks (e.g. ``configure``,
85``compile`` and so forth) that work for all Autotooled packages. It
86should usually be enough to define a few standard variables and then
87simply ``inherit autotools``. These classes can also work with software
88that emulates Autotools. For more information, see the
89":ref:`new-recipe-autotooled-package`" section
90in the Yocto Project Development Tasks Manual.
91
92By default, the ``autotools*`` classes use out-of-tree builds (i.e.
93``autotools.bbclass`` building with ``B != S``).
94
95If the software being built by a recipe does not support using
96out-of-tree builds, you should have the recipe inherit the
97``autotools-brokensep`` class. The ``autotools-brokensep`` class behaves
98the same as the ``autotools`` class but builds with :term:`B`
99== :term:`S`. This method is useful when out-of-tree build
100support is either not present or is broken.
101
102.. note::
103
104 It is recommended that out-of-tree support be fixed and used if at
105 all possible.
106
107It's useful to have some idea of how the tasks defined by the
108``autotools*`` classes work and what they do behind the scenes.
109
110- :ref:`ref-tasks-configure` - Regenerates the
111 configure script (using ``autoreconf``) and then launches it with a
112 standard set of arguments used during cross-compilation. You can pass
113 additional parameters to ``configure`` through the ``EXTRA_OECONF``
114 or :term:`PACKAGECONFIG_CONFARGS`
115 variables.
116
117- :ref:`ref-tasks-compile` - Runs ``make`` with
118 arguments that specify the compiler and linker. You can pass
119 additional arguments through the ``EXTRA_OEMAKE`` variable.
120
121- :ref:`ref-tasks-install` - Runs ``make install`` and
122 passes in ``${``\ :term:`D`\ ``}`` as ``DESTDIR``.
123
124.. _ref-classes-base:
125
126``base.bbclass``
127================
128
129The ``base`` class is special in that every ``.bb`` file implicitly
130inherits the class. This class contains definitions for standard basic
131tasks such as fetching, unpacking, configuring (empty by default),
132compiling (runs any ``Makefile`` present), installing (empty by default)
133and packaging (empty by default). These classes are often overridden or
134extended by other classes such as the
135:ref:`autotools <ref-classes-autotools>` class or the
136:ref:`package <ref-classes-package>` class.
137
138The class also contains some commonly used functions such as
139``oe_runmake``, which runs ``make`` with the arguments specified in
140:term:`EXTRA_OEMAKE` variable as well as the
141arguments passed directly to ``oe_runmake``.
142
143.. _ref-classes-bash-completion:
144
145``bash-completion.bbclass``
146===========================
147
148Sets up packaging and dependencies appropriate for recipes that build
149software that includes bash-completion data.
150
151.. _ref-classes-bin-package:
152
153``bin_package.bbclass``
154=======================
155
156The ``bin_package`` class is a helper class for recipes that extract the
157contents of a binary package (e.g. an RPM) and install those contents
158rather than building the binary from source. The binary package is
159extracted and new packages in the configured output package format are
160created. Extraction and installation of proprietary binaries is a good
161example use for this class.
162
163.. note::
164
165 For RPMs and other packages that do not contain a subdirectory, you
166 should specify an appropriate fetcher parameter to point to the
Andrew Geissler4c19ea12020-10-27 13:52:24 -0500167 subdirectory. For example, if BitBake is using the Git fetcher (``git://``),
168 the "subpath" parameter limits the checkout to a specific subpath
169 of the tree. Here is an example where ``${BP}`` is used so that the files
170 are extracted into the subdirectory expected by the default value of
171 ``S``:
Andrew Geisslerc9f78652020-09-18 14:11:35 -0500172 ::
173
174 SRC_URI = "git://example.com/downloads/somepackage.rpm;subpath=${BP}"
175
176
Andrew Geissler4c19ea12020-10-27 13:52:24 -0500177 See the ":ref:`bitbake-user-manual/bitbake-user-manual-fetching:fetchers`" section in the BitBake User Manual for
178 more information on supported BitBake Fetchers.
Andrew Geisslerc9f78652020-09-18 14:11:35 -0500179
180.. _ref-classes-binconfig:
181
182``binconfig.bbclass``
183=====================
184
185The ``binconfig`` class helps to correct paths in shell scripts.
186
187Before ``pkg-config`` had become widespread, libraries shipped shell
188scripts to give information about the libraries and include paths needed
189to build software (usually named ``LIBNAME-config``). This class assists
190any recipe using such scripts.
191
192During staging, the OpenEmbedded build system installs such scripts into
193the ``sysroots/`` directory. Inheriting this class results in all paths
194in these scripts being changed to point into the ``sysroots/`` directory
195so that all builds that use the script use the correct directories for
196the cross compiling layout. See the
197:term:`BINCONFIG_GLOB` variable for more
198information.
199
200.. _ref-classes-binconfig-disabled:
201
202``binconfig-disabled.bbclass``
203==============================
204
205An alternative version of the :ref:`binconfig <ref-classes-binconfig>`
206class, which disables binary configuration scripts by making them return
207an error in favor of using ``pkg-config`` to query the information. The
208scripts to be disabled should be specified using the
209:term:`BINCONFIG` variable within the recipe inheriting
210the class.
211
212.. _ref-classes-blacklist:
213
214``blacklist.bbclass``
215=====================
216
217The ``blacklist`` class prevents the OpenEmbedded build system from
218building specific recipes (blacklists them). To use this class, inherit
219the class globally and set :term:`PNBLACKLIST` for
220each recipe you wish to blacklist. Specify the :term:`PN`
221value as a variable flag (varflag) and provide a reason, which is
222reported, if the package is requested to be built as the value. For
223example, if you want to blacklist a recipe called "exoticware", you add
224the following to your ``local.conf`` or distribution configuration:
225::
226
227 INHERIT += "blacklist"
228 PNBLACKLIST[exoticware] = "Not supported by our organization."
229
230.. _ref-classes-buildhistory:
231
232``buildhistory.bbclass``
233========================
234
235The ``buildhistory`` class records a history of build output metadata,
236which can be used to detect possible regressions as well as used for
237analysis of the build output. For more information on using Build
238History, see the
239":ref:`dev-manual/dev-manual-common-tasks:maintaining build output quality`"
240section in the Yocto Project Development Tasks Manual.
241
242.. _ref-classes-buildstats:
243
244``buildstats.bbclass``
245======================
246
247The ``buildstats`` class records performance statistics about each task
248executed during the build (e.g. elapsed time, CPU usage, and I/O usage).
249
250When you use this class, the output goes into the
251:term:`BUILDSTATS_BASE` directory, which defaults
252to ``${TMPDIR}/buildstats/``. You can analyze the elapsed time using
253``scripts/pybootchartgui/pybootchartgui.py``, which produces a cascading
254chart of the entire build process and can be useful for highlighting
255bottlenecks.
256
257Collecting build statistics is enabled by default through the
258:term:`USER_CLASSES` variable from your
259``local.conf`` file. Consequently, you do not have to do anything to
260enable the class. However, if you want to disable the class, simply
261remove "buildstats" from the ``USER_CLASSES`` list.
262
263.. _ref-classes-buildstats-summary:
264
265``buildstats-summary.bbclass``
266==============================
267
268When inherited globally, prints statistics at the end of the build on
269sstate re-use. In order to function, this class requires the
270:ref:`buildstats <ref-classes-buildstats>` class be enabled.
271
272.. _ref-classes-ccache:
273
274``ccache.bbclass``
275==================
276
277The ``ccache`` class enables the C/C++ Compiler Cache for the build.
278This class is used to give a minor performance boost during the build.
279However, using the class can lead to unexpected side-effects. Thus, it
280is recommended that you do not use this class. See
281http://ccache.samba.org/ for information on the C/C++ Compiler
282Cache.
283
284.. _ref-classes-chrpath:
285
286``chrpath.bbclass``
287===================
288
289The ``chrpath`` class is a wrapper around the "chrpath" utility, which
290is used during the build process for ``nativesdk``, ``cross``, and
291``cross-canadian`` recipes to change ``RPATH`` records within binaries
292in order to make them relocatable.
293
294.. _ref-classes-clutter:
295
296``clutter.bbclass``
297===================
298
299The ``clutter`` class consolidates the major and minor version naming
300and other common items used by Clutter and related recipes.
301
302.. note::
303
304 Unlike some other classes related to specific libraries, recipes
305 building other software that uses Clutter do not need to inherit this
306 class unless they use the same recipe versioning scheme that the
307 Clutter and related recipes do.
308
309.. _ref-classes-cmake:
310
311``cmake.bbclass``
312=================
313
314The ``cmake`` class allows for recipes that need to build software using
315the `CMake <https://cmake.org/overview/>`__ build system. You can use
316the :term:`EXTRA_OECMAKE` variable to specify
317additional configuration options to be passed using the ``cmake``
318command line.
319
320On the occasion that you would be installing custom CMake toolchain
321files supplied by the application being built, you should install them
322to the preferred CMake Module directory: ``${D}${datadir}/cmake/``
323Modules during
324:ref:`ref-tasks-install`.
325
326.. _ref-classes-cml1:
327
328``cml1.bbclass``
329================
330
331The ``cml1`` class provides basic support for the Linux kernel style
332build configuration system.
333
334.. _ref-classes-compress_doc:
335
336``compress_doc.bbclass``
337========================
338
339Enables compression for man pages and info pages. This class is intended
340to be inherited globally. The default compression mechanism is gz (gzip)
341but you can select an alternative mechanism by setting the
342:term:`DOC_COMPRESS` variable.
343
344.. _ref-classes-copyleft_compliance:
345
346``copyleft_compliance.bbclass``
347===============================
348
349The ``copyleft_compliance`` class preserves source code for the purposes
350of license compliance. This class is an alternative to the ``archiver``
351class and is still used by some users even though it has been deprecated
352in favor of the :ref:`archiver <ref-classes-archiver>` class.
353
354.. _ref-classes-copyleft_filter:
355
356``copyleft_filter.bbclass``
357===========================
358
359A class used by the :ref:`archiver <ref-classes-archiver>` and
360:ref:`copyleft_compliance <ref-classes-copyleft_compliance>` classes
361for filtering licenses. The ``copyleft_filter`` class is an internal
362class and is not intended to be used directly.
363
364.. _ref-classes-core-image:
365
366``core-image.bbclass``
367======================
368
369The ``core-image`` class provides common definitions for the
370``core-image-*`` image recipes, such as support for additional
371:term:`IMAGE_FEATURES`.
372
373.. _ref-classes-cpan:
374
375``cpan*.bbclass``
376=================
377
378The ``cpan*`` classes support Perl modules.
379
380Recipes for Perl modules are simple. These recipes usually only need to
381point to the source's archive and then inherit the proper class file.
382Building is split into two methods depending on which method the module
383authors used.
384
385- Modules that use old ``Makefile.PL``-based build system require
386 ``cpan.bbclass`` in their recipes.
387
388- Modules that use ``Build.PL``-based build system require using
389 ``cpan_build.bbclass`` in their recipes.
390
391Both build methods inherit the ``cpan-base`` class for basic Perl
392support.
393
394.. _ref-classes-cross:
395
396``cross.bbclass``
397=================
398
399The ``cross`` class provides support for the recipes that build the
400cross-compilation tools.
401
402.. _ref-classes-cross-canadian:
403
404``cross-canadian.bbclass``
405==========================
406
407The ``cross-canadian`` class provides support for the recipes that build
408the Canadian Cross-compilation tools for SDKs. See the
409":ref:`overview-manual/overview-manual-concepts:cross-development toolchain generation`"
410section in the Yocto Project Overview and Concepts Manual for more
411discussion on these cross-compilation tools.
412
413.. _ref-classes-crosssdk:
414
415``crosssdk.bbclass``
416====================
417
418The ``crosssdk`` class provides support for the recipes that build the
419cross-compilation tools used for building SDKs. See the
420":ref:`overview-manual/overview-manual-concepts:cross-development toolchain generation`"
421section in the Yocto Project Overview and Concepts Manual for more
422discussion on these cross-compilation tools.
423
424.. _ref-classes-debian:
425
426``debian.bbclass``
427==================
428
429The ``debian`` class renames output packages so that they follow the
430Debian naming policy (i.e. ``glibc`` becomes ``libc6`` and
431``glibc-devel`` becomes ``libc6-dev``.) Renaming includes the library
432name and version as part of the package name.
433
434If a recipe creates packages for multiple libraries (shared object files
435of ``.so`` type), use the :term:`LEAD_SONAME`
436variable in the recipe to specify the library on which to apply the
437naming scheme.
438
439.. _ref-classes-deploy:
440
441``deploy.bbclass``
442==================
443
444The ``deploy`` class handles deploying files to the
445:term:`DEPLOY_DIR_IMAGE` directory. The main
446function of this class is to allow the deploy step to be accelerated by
447shared state. Recipes that inherit this class should define their own
448:ref:`ref-tasks-deploy` function to copy the files to be
449deployed to :term:`DEPLOYDIR`, and use ``addtask`` to
450add the task at the appropriate place, which is usually after
451:ref:`ref-tasks-compile` or
452:ref:`ref-tasks-install`. The class then takes care of
453staging the files from ``DEPLOYDIR`` to ``DEPLOY_DIR_IMAGE``.
454
455.. _ref-classes-devshell:
456
457``devshell.bbclass``
458====================
459
460The ``devshell`` class adds the ``do_devshell`` task. Distribution
461policy dictates whether to include this class. See the ":ref:`platdev-appdev-devshell`"
462section in the Yocto Project Development Tasks Manual for more
463information about using ``devshell``.
464
465.. _ref-classes-devupstream:
466
467``devupstream.bbclass``
468=======================
469
470The ``devupstream`` class uses
471:term:`BBCLASSEXTEND` to add a variant of the
472recipe that fetches from an alternative URI (e.g. Git) instead of a
473tarball. Following is an example:
474::
475
476 BBCLASSEXTEND = "devupstream:target"
477 SRC_URI_class-devupstream = "git://git.example.com/example"
478 SRCREV_class-devupstream = "abcd1234"
479
480Adding the above statements to your recipe creates a variant that has
481:term:`DEFAULT_PREFERENCE` set to "-1".
482Consequently, you need to select the variant of the recipe to use it.
483Any development-specific adjustments can be done by using the
484``class-devupstream`` override. Here is an example:
485::
486
487 DEPENDS_append_class-devupstream = " gperf-native"
488 do_configure_prepend_class-devupstream() {
489 touch ${S}/README
490 }
491
492The class
493currently only supports creating a development variant of the target
494recipe, not ``native`` or ``nativesdk`` variants.
495
496The ``BBCLASSEXTEND`` syntax (i.e. ``devupstream:target``) provides
497support for ``native`` and ``nativesdk`` variants. Consequently, this
498functionality can be added in a future release.
499
500Support for other version control systems such as Subversion is limited
501due to BitBake's automatic fetch dependencies (e.g.
502``subversion-native``).
503
Andrew Geisslerc9f78652020-09-18 14:11:35 -0500504.. _ref-classes-distutils:
505
506``distutils*.bbclass``
507======================
508
509The ``distutils*`` classes support recipes for Python version 2.x
510extensions, which are simple. These recipes usually only need to point
511to the source's archive and then inherit the proper class. Building is
512split into two methods depending on which method the module authors
513used.
514
515- Extensions that use an Autotools-based build system require Autotools
516 and the classes based on ``distutils`` in their recipes.
517
518- Extensions that use build systems based on ``distutils`` require the
519 ``distutils`` class in their recipes.
520
521- Extensions that use build systems based on ``setuptools`` require the
522 :ref:`setuptools <ref-classes-setuptools>` class in their recipes.
523
524The ``distutils-common-base`` class is required by some of the
525``distutils*`` classes to provide common Python2 support.
526
527.. _ref-classes-distutils3:
528
529``distutils3*.bbclass``
530=======================
531
532The ``distutils3*`` classes support recipes for Python version 3.x
533extensions, which are simple. These recipes usually only need to point
534to the source's archive and then inherit the proper class. Building is
535split into three methods depending on which method the module authors
536used.
537
538- Extensions that use an Autotools-based build system require Autotools
539 and ``distutils``-based classes in their recipes.
540
541- Extensions that use ``distutils``-based build systems require the
542 ``distutils`` class in their recipes.
543
544- Extensions that use build systems based on ``setuptools3`` require
545 the :ref:`setuptools3 <ref-classes-setuptools>` class in their
546 recipes.
547
548The ``distutils3*`` classes either inherit their corresponding
549``distutils*`` class or replicate them using a Python3 version instead
550(e.g. ``distutils3-base`` inherits ``distutils-common-base``, which is
551the same as ``distutils-base`` but inherits ``python3native`` instead of
552``pythonnative``).
553
554.. _ref-classes-externalsrc:
555
556``externalsrc.bbclass``
557=======================
558
559The ``externalsrc`` class supports building software from source code
560that is external to the OpenEmbedded build system. Building software
561from an external source tree means that the build system's normal fetch,
562unpack, and patch process is not used.
563
564By default, the OpenEmbedded build system uses the :term:`S`
565and :term:`B` variables to locate unpacked recipe source code
566and to build it, respectively. When your recipe inherits the
567``externalsrc`` class, you use the
568:term:`EXTERNALSRC` and
569:term:`EXTERNALSRC_BUILD` variables to
570ultimately define ``S`` and ``B``.
571
572By default, this class expects the source code to support recipe builds
573that use the :term:`B` variable to point to the directory in
574which the OpenEmbedded build system places the generated objects built
575from the recipes. By default, the ``B`` directory is set to the
576following, which is separate from the source directory (``S``):
577::
578
579 ${WORKDIR}/${BPN}/{PV}/
580
581See these variables for more information:
582:term:`WORKDIR`, :term:`BPN`, and
583:term:`PV`,
584
585For more information on the ``externalsrc`` class, see the comments in
586``meta/classes/externalsrc.bbclass`` in the :term:`Source Directory`.
587For information on how to use the
588``externalsrc`` class, see the
589":ref:`dev-manual/dev-manual-common-tasks:building software from an external source`"
590section in the Yocto Project Development Tasks Manual.
591
592.. _ref-classes-extrausers:
593
594``extrausers.bbclass``
595======================
596
597The ``extrausers`` class allows additional user and group configuration
598to be applied at the image level. Inheriting this class either globally
599or from an image recipe allows additional user and group operations to
600be performed using the
601:term:`EXTRA_USERS_PARAMS` variable.
602
603.. note::
604
605 The user and group operations added using the
606 extrausers
607 class are not tied to a specific recipe outside of the recipe for the
608 image. Thus, the operations can be performed across the image as a
609 whole. Use the
610 useradd
611 class to add user and group configuration to a specific recipe.
612
613Here is an example that uses this class in an image recipe:
614::
615
616 inherit extrausers
617 EXTRA_USERS_PARAMS = "\
618 useradd -p '' tester; \
619 groupadd developers; \
620 userdel nobody; \
621 groupdel -g video; \
622 groupmod -g 1020 developers; \
623 usermod -s /bin/sh tester; \
624 "
625
626Here is an example that adds two users named "tester-jim" and "tester-sue" and assigns
627passwords:
628::
629
630 inherit extrausers
631 EXTRA_USERS_PARAMS = "\
632 useradd -P tester01 tester-jim; \
633 useradd -P tester01 tester-sue; \
634 "
635
636Finally, here is an example that sets the root password to "1876*18":
637::
638
639 inherit extrausers
640 EXTRA_USERS_PARAMS = "\
641 usermod -P 1876*18 root; \
642 "
643
Andrew Geissler6ce62a22020-11-30 19:58:47 -0600644.. _ref-classes-features_check:
645
646``features_check.bbclass``
647=================================
648
649The ``features_check`` class allows individual recipes to check
650for required and conflicting
651:term:`DISTRO_FEATURES`, :term:`MACHINE_FEATURES` or :term:`COMBINED_FEATURES`.
652
653This class provides support for the following variables:
654
655- :term:`REQUIRED_DISTRO_FEATURES`
656- :term:`CONFLICT_DISTRO_FEATURES`
657- :term:`ANY_OF_DISTRO_FEATURES`
658- ``REQUIRED_MACHINE_FEATURES``
659- ``CONFLICT_MACHINE_FEATURES``
660- ``ANY_OF_MACHINE_FEATURES``
661- ``REQUIRED_COMBINED_FEATURES``
662- ``CONFLICT_COMBINED_FEATURES``
663- ``ANY_OF_COMBINED_FEATURES``
664
665If any conditions specified in the recipe using the above
666variables are not met, the recipe will be skipped, and if the
667build system attempts to build the recipe then an error will be
668triggered.
669
Andrew Geisslerc9f78652020-09-18 14:11:35 -0500670.. _ref-classes-fontcache:
671
672``fontcache.bbclass``
673=====================
674
675The ``fontcache`` class generates the proper post-install and
676post-remove (postinst and postrm) scriptlets for font packages. These
677scriptlets call ``fc-cache`` (part of ``Fontconfig``) to add the fonts
678to the font information cache. Since the cache files are
679architecture-specific, ``fc-cache`` runs using QEMU if the postinst
680scriptlets need to be run on the build host during image creation.
681
682If the fonts being installed are in packages other than the main
683package, set :term:`FONT_PACKAGES` to specify the
684packages containing the fonts.
685
686.. _ref-classes-fs-uuid:
687
688``fs-uuid.bbclass``
689===================
690
691The ``fs-uuid`` class extracts UUID from
692``${``\ :term:`ROOTFS`\ ``}``, which must have been built
693by the time that this function gets called. The ``fs-uuid`` class only
694works on ``ext`` file systems and depends on ``tune2fs``.
695
696.. _ref-classes-gconf:
697
698``gconf.bbclass``
699=================
700
701The ``gconf`` class provides common functionality for recipes that need
702to install GConf schemas. The schemas will be put into a separate
703package (``${``\ :term:`PN`\ ``}-gconf``) that is created
704automatically when this class is inherited. This package uses the
705appropriate post-install and post-remove (postinst/postrm) scriptlets to
706register and unregister the schemas in the target image.
707
708.. _ref-classes-gettext:
709
710``gettext.bbclass``
711===================
712
713The ``gettext`` class provides support for building software that uses
714the GNU ``gettext`` internationalization and localization system. All
715recipes building software that use ``gettext`` should inherit this
716class.
717
718.. _ref-classes-gnomebase:
719
720``gnomebase.bbclass``
721=====================
722
723The ``gnomebase`` class is the base class for recipes that build
724software from the GNOME stack. This class sets
725:term:`SRC_URI` to download the source from the GNOME
726mirrors as well as extending :term:`FILES` with the typical
727GNOME installation paths.
728
729.. _ref-classes-gobject-introspection:
730
731``gobject-introspection.bbclass``
732=================================
733
734Provides support for recipes building software that supports GObject
735introspection. This functionality is only enabled if the
736"gobject-introspection-data" feature is in
737:term:`DISTRO_FEATURES` as well as
738"qemu-usermode" being in
739:term:`MACHINE_FEATURES`.
740
741.. note::
742
743 This functionality is backfilled by default and, if not applicable,
Andrew Geissler4c19ea12020-10-27 13:52:24 -0500744 should be disabled through ``DISTRO_FEATURES_BACKFILL_CONSIDERED`` or
745 ``MACHINE_FEATURES_BACKFILL_CONSIDERED``, respectively.
Andrew Geisslerc9f78652020-09-18 14:11:35 -0500746
747.. _ref-classes-grub-efi:
748
749``grub-efi.bbclass``
750====================
751
752The ``grub-efi`` class provides ``grub-efi``-specific functions for
753building bootable images.
754
755This class supports several variables:
756
757- :term:`INITRD`: Indicates list of filesystem images to
758 concatenate and use as an initial RAM disk (initrd) (optional).
759
760- :term:`ROOTFS`: Indicates a filesystem image to include
761 as the root filesystem (optional).
762
763- :term:`GRUB_GFXSERIAL`: Set this to "1" to have
764 graphics and serial in the boot menu.
765
766- :term:`LABELS`: A list of targets for the automatic
767 configuration.
768
769- :term:`APPEND`: An override list of append strings for
770 each ``LABEL``.
771
772- :term:`GRUB_OPTS`: Additional options to add to the
773 configuration (optional). Options are delimited using semi-colon
774 characters (``;``).
775
776- :term:`GRUB_TIMEOUT`: Timeout before executing
777 the default ``LABEL`` (optional).
778
779.. _ref-classes-gsettings:
780
781``gsettings.bbclass``
782=====================
783
784The ``gsettings`` class provides common functionality for recipes that
785need to install GSettings (glib) schemas. The schemas are assumed to be
786part of the main package. Appropriate post-install and post-remove
787(postinst/postrm) scriptlets are added to register and unregister the
788schemas in the target image.
789
790.. _ref-classes-gtk-doc:
791
792``gtk-doc.bbclass``
793===================
794
795The ``gtk-doc`` class is a helper class to pull in the appropriate
796``gtk-doc`` dependencies and disable ``gtk-doc``.
797
798.. _ref-classes-gtk-icon-cache:
799
800``gtk-icon-cache.bbclass``
801==========================
802
803The ``gtk-icon-cache`` class generates the proper post-install and
804post-remove (postinst/postrm) scriptlets for packages that use GTK+ and
805install icons. These scriptlets call ``gtk-update-icon-cache`` to add
806the fonts to GTK+'s icon cache. Since the cache files are
807architecture-specific, ``gtk-update-icon-cache`` is run using QEMU if
808the postinst scriptlets need to be run on the build host during image
809creation.
810
811.. _ref-classes-gtk-immodules-cache:
812
813``gtk-immodules-cache.bbclass``
814===============================
815
816The ``gtk-immodules-cache`` class generates the proper post-install and
817post-remove (postinst/postrm) scriptlets for packages that install GTK+
818input method modules for virtual keyboards. These scriptlets call
819``gtk-update-icon-cache`` to add the input method modules to the cache.
820Since the cache files are architecture-specific,
821``gtk-update-icon-cache`` is run using QEMU if the postinst scriptlets
822need to be run on the build host during image creation.
823
824If the input method modules being installed are in packages other than
825the main package, set
826:term:`GTKIMMODULES_PACKAGES` to specify
827the packages containing the modules.
828
829.. _ref-classes-gzipnative:
830
831``gzipnative.bbclass``
832======================
833
834The ``gzipnative`` class enables the use of different native versions of
835``gzip`` and ``pigz`` rather than the versions of these tools from the
836build host.
837
838.. _ref-classes-icecc:
839
840``icecc.bbclass``
841=================
842
843The ``icecc`` class supports
844`Icecream <https://github.com/icecc/icecream>`__, which facilitates
845taking compile jobs and distributing them among remote machines.
846
847The class stages directories with symlinks from ``gcc`` and ``g++`` to
848``icecc``, for both native and cross compilers. Depending on each
849configure or compile, the OpenEmbedded build system adds the directories
850at the head of the ``PATH`` list and then sets the ``ICECC_CXX`` and
851``ICEC_CC`` variables, which are the paths to the ``g++`` and ``gcc``
852compilers, respectively.
853
854For the cross compiler, the class creates a ``tar.gz`` file that
855contains the Yocto Project toolchain and sets ``ICECC_VERSION``, which
856is the version of the cross-compiler used in the cross-development
857toolchain, accordingly.
858
859The class handles all three different compile stages (i.e native
860,cross-kernel and target) and creates the necessary environment
861``tar.gz`` file to be used by the remote machines. The class also
862supports SDK generation.
863
864If :term:`ICECC_PATH` is not set in your
865``local.conf`` file, then the class tries to locate the ``icecc`` binary
866using ``which``. If :term:`ICECC_ENV_EXEC` is set
867in your ``local.conf`` file, the variable should point to the
868``icecc-create-env`` script provided by the user. If you do not point to
869a user-provided script, the build system uses the default script
870provided by the recipe ``icecc-create-env-native.bb``.
871
872.. note::
873
874 This script is a modified version and not the one that comes with
875 icecc.
876
877If you do not want the Icecream distributed compile support to apply to
878specific recipes or classes, you can effectively "blacklist" them by
879listing the recipes and classes using the
880:term:`ICECC_USER_PACKAGE_BL` and
881:term:`ICECC_USER_CLASS_BL`, variables,
882respectively, in your ``local.conf`` file. Doing so causes the
883OpenEmbedded build system to handle these compilations locally.
884
885Additionally, you can list recipes using the
886:term:`ICECC_USER_PACKAGE_WL` variable in
887your ``local.conf`` file to force ``icecc`` to be enabled for recipes
888using an empty :term:`PARALLEL_MAKE` variable.
889
890Inheriting the ``icecc`` class changes all sstate signatures.
891Consequently, if a development team has a dedicated build system that
892populates :term:`SSTATE_MIRRORS` and they want to
893reuse sstate from ``SSTATE_MIRRORS``, then all developers and the build
894system need to either inherit the ``icecc`` class or nobody should.
895
896At the distribution level, you can inherit the ``icecc`` class to be
897sure that all builders start with the same sstate signatures. After
898inheriting the class, you can then disable the feature by setting the
899:term:`ICECC_DISABLED` variable to "1" as follows:
900::
901
902 INHERIT_DISTRO_append = " icecc"
903 ICECC_DISABLED ??= "1"
904
905This practice
906makes sure everyone is using the same signatures but also requires
907individuals that do want to use Icecream to enable the feature
908individually as follows in your ``local.conf`` file:
909::
910
911 ICECC_DISABLED = ""
912
913.. _ref-classes-image:
914
915``image.bbclass``
916=================
917
918The ``image`` class helps support creating images in different formats.
919First, the root filesystem is created from packages using one of the
920``rootfs*.bbclass`` files (depending on the package format used) and
921then one or more image files are created.
922
923- The ``IMAGE_FSTYPES`` variable controls the types of images to
924 generate.
925
926- The ``IMAGE_INSTALL`` variable controls the list of packages to
927 install into the image.
928
929For information on customizing images, see the
930":ref:`usingpoky-extend-customimage`" section
931in the Yocto Project Development Tasks Manual. For information on how
932images are created, see the
933":ref:`images-dev-environment`" section in the
934Yocto Project Overview and Concpets Manual.
935
936.. _ref-classes-image-buildinfo:
937
938``image-buildinfo.bbclass``
939===========================
940
941The ``image-buildinfo`` class writes information to the target
942filesystem on ``/etc/build``.
943
944.. _ref-classes-image_types:
945
946``image_types.bbclass``
947=======================
948
949The ``image_types`` class defines all of the standard image output types
950that you can enable through the
951:term:`IMAGE_FSTYPES` variable. You can use this
952class as a reference on how to add support for custom image output
953types.
954
955By default, the :ref:`image <ref-classes-image>` class automatically
956enables the ``image_types`` class. The ``image`` class uses the
957``IMGCLASSES`` variable as follows:
958::
959
960 IMGCLASSES = "rootfs_${IMAGE_PKGTYPE} image_types ${IMAGE_CLASSES}"
961 IMGCLASSES += "${@['populate_sdk_base', 'populate_sdk_ext']['linux' in d.getVar("SDK_OS")]}"
962 IMGCLASSES += "${@bb.utils.contains_any('IMAGE_FSTYPES', 'live iso hddimg', 'image-live', '', d)}"
963 IMGCLASSES += "${@bb.utils.contains('IMAGE_FSTYPES', 'container', 'image-container', '', d)}"
964 IMGCLASSES += "image_types_wic"
965 IMGCLASSES += "rootfs-postcommands"
966 IMGCLASSES += "image-postinst-intercepts"
967 inherit ${IMGCLASSES}
968
969The ``image_types`` class also handles conversion and compression of images.
970
971.. note::
972
973 To build a VMware VMDK image, you need to add "wic.vmdk" to
Andrew Geissler4c19ea12020-10-27 13:52:24 -0500974 ``IMAGE_FSTYPES``. This would also be similar for Virtual Box Virtual Disk
975 Image ("vdi") and QEMU Copy On Write Version 2 ("qcow2") images.
Andrew Geisslerc9f78652020-09-18 14:11:35 -0500976
977.. _ref-classes-image-live:
978
979``image-live.bbclass``
980======================
981
982This class controls building "live" (i.e. HDDIMG and ISO) images. Live
983images contain syslinux for legacy booting, as well as the bootloader
984specified by :term:`EFI_PROVIDER` if
985:term:`MACHINE_FEATURES` contains "efi".
986
987Normally, you do not use this class directly. Instead, you add "live" to
988:term:`IMAGE_FSTYPES`.
989
990.. _ref-classes-image-mklibs:
991
992``image-mklibs.bbclass``
993========================
994
995The ``image-mklibs`` class enables the use of the ``mklibs`` utility
996during the :ref:`ref-tasks-rootfs` task, which optimizes
997the size of libraries contained in the image.
998
999By default, the class is enabled in the ``local.conf.template`` using
1000the :term:`USER_CLASSES` variable as follows:
1001::
1002
1003 USER_CLASSES ?= "buildstats image-mklibs image-prelink"
1004
1005.. _ref-classes-image-prelink:
1006
1007``image-prelink.bbclass``
1008=========================
1009
1010The ``image-prelink`` class enables the use of the ``prelink`` utility
1011during the :ref:`ref-tasks-rootfs` task, which optimizes
1012the dynamic linking of shared libraries to reduce executable startup
1013time.
1014
1015By default, the class is enabled in the ``local.conf.template`` using
1016the :term:`USER_CLASSES` variable as follows:
1017::
1018
1019 USER_CLASSES ?= "buildstats image-mklibs image-prelink"
1020
1021.. _ref-classes-insane:
1022
1023``insane.bbclass``
1024==================
1025
1026The ``insane`` class adds a step to the package generation process so
1027that output quality assurance checks are generated by the OpenEmbedded
1028build system. A range of checks are performed that check the build's
1029output for common problems that show up during runtime. Distribution
1030policy usually dictates whether to include this class.
1031
1032You can configure the sanity checks so that specific test failures
1033either raise a warning or an error message. Typically, failures for new
1034tests generate a warning. Subsequent failures for the same test would
1035then generate an error message once the metadata is in a known and good
Andrew Geissler4c19ea12020-10-27 13:52:24 -05001036condition. See the ":doc:`ref-qa-checks`" Chapter for a list of all the warning
1037and error messages you might encounter using a default configuration.
Andrew Geisslerc9f78652020-09-18 14:11:35 -05001038
1039Use the :term:`WARN_QA` and
1040:term:`ERROR_QA` variables to control the behavior of
1041these checks at the global level (i.e. in your custom distro
1042configuration). However, to skip one or more checks in recipes, you
1043should use :term:`INSANE_SKIP`. For example, to skip
1044the check for symbolic link ``.so`` files in the main package of a
1045recipe, add the following to the recipe. You need to realize that the
1046package name override, in this example ``${PN}``, must be used:
1047::
1048
1049 INSANE_SKIP_${PN} += "dev-so"
1050
1051Please keep in mind that the QA checks
1052exist in order to detect real or potential problems in the packaged
1053output. So exercise caution when disabling these checks.
1054
1055The following list shows the tests you can list with the ``WARN_QA`` and
1056``ERROR_QA`` variables:
1057
1058- ``already-stripped:`` Checks that produced binaries have not
1059 already been stripped prior to the build system extracting debug
1060 symbols. It is common for upstream software projects to default to
1061 stripping debug symbols for output binaries. In order for debugging
1062 to work on the target using ``-dbg`` packages, this stripping must be
1063 disabled.
1064
1065- ``arch:`` Checks the Executable and Linkable Format (ELF) type, bit
1066 size, and endianness of any binaries to ensure they match the target
1067 architecture. This test fails if any binaries do not match the type
1068 since there would be an incompatibility. The test could indicate that
1069 the wrong compiler or compiler options have been used. Sometimes
1070 software, like bootloaders, might need to bypass this check.
1071
1072- ``buildpaths:`` Checks for paths to locations on the build host
1073 inside the output files. Currently, this test triggers too many false
1074 positives and thus is not normally enabled.
1075
1076- ``build-deps:`` Determines if a build-time dependency that is
1077 specified through :term:`DEPENDS`, explicit
1078 :term:`RDEPENDS`, or task-level dependencies exists
1079 to match any runtime dependency. This determination is particularly
1080 useful to discover where runtime dependencies are detected and added
1081 during packaging. If no explicit dependency has been specified within
1082 the metadata, at the packaging stage it is too late to ensure that
1083 the dependency is built, and thus you can end up with an error when
1084 the package is installed into the image during the
1085 :ref:`ref-tasks-rootfs` task because the auto-detected
1086 dependency was not satisfied. An example of this would be where the
1087 :ref:`update-rc.d <ref-classes-update-rc.d>` class automatically
1088 adds a dependency on the ``initscripts-functions`` package to
1089 packages that install an initscript that refers to
1090 ``/etc/init.d/functions``. The recipe should really have an explicit
1091 ``RDEPENDS`` for the package in question on ``initscripts-functions``
1092 so that the OpenEmbedded build system is able to ensure that the
1093 ``initscripts`` recipe is actually built and thus the
1094 ``initscripts-functions`` package is made available.
1095
1096- ``compile-host-path:`` Checks the
1097 :ref:`ref-tasks-compile` log for indications that
1098 paths to locations on the build host were used. Using such paths
1099 might result in host contamination of the build output.
1100
1101- ``debug-deps:`` Checks that all packages except ``-dbg`` packages
1102 do not depend on ``-dbg`` packages, which would cause a packaging
1103 bug.
1104
1105- ``debug-files:`` Checks for ``.debug`` directories in anything but
1106 the ``-dbg`` package. The debug files should all be in the ``-dbg``
1107 package. Thus, anything packaged elsewhere is incorrect packaging.
1108
1109- ``dep-cmp:`` Checks for invalid version comparison statements in
1110 runtime dependency relationships between packages (i.e. in
1111 :term:`RDEPENDS`,
1112 :term:`RRECOMMENDS`,
1113 :term:`RSUGGESTS`,
1114 :term:`RPROVIDES`,
1115 :term:`RREPLACES`, and
1116 :term:`RCONFLICTS` variable values). Any invalid
1117 comparisons might trigger failures or undesirable behavior when
1118 passed to the package manager.
1119
1120- ``desktop:`` Runs the ``desktop-file-validate`` program against any
1121 ``.desktop`` files to validate their contents against the
1122 specification for ``.desktop`` files.
1123
1124- ``dev-deps:`` Checks that all packages except ``-dev`` or
1125 ``-staticdev`` packages do not depend on ``-dev`` packages, which
1126 would be a packaging bug.
1127
1128- ``dev-so:`` Checks that the ``.so`` symbolic links are in the
1129 ``-dev`` package and not in any of the other packages. In general,
1130 these symlinks are only useful for development purposes. Thus, the
1131 ``-dev`` package is the correct location for them. Some very rare
1132 cases do exist for dynamically loaded modules where these symlinks
1133 are needed instead in the main package.
1134
1135- ``file-rdeps:`` Checks that file-level dependencies identified by
1136 the OpenEmbedded build system at packaging time are satisfied. For
1137 example, a shell script might start with the line ``#!/bin/bash``.
1138 This line would translate to a file dependency on ``/bin/bash``. Of
1139 the three package managers that the OpenEmbedded build system
1140 supports, only RPM directly handles file-level dependencies,
1141 resolving them automatically to packages providing the files.
1142 However, the lack of that functionality in the other two package
1143 managers does not mean the dependencies do not still need resolving.
1144 This QA check attempts to ensure that explicitly declared
1145 :term:`RDEPENDS` exist to handle any file-level
1146 dependency detected in packaged files.
1147
1148- ``files-invalid:`` Checks for :term:`FILES` variable
1149 values that contain "//", which is invalid.
1150
1151- ``host-user-contaminated:`` Checks that no package produced by the
1152 recipe contains any files outside of ``/home`` with a user or group
1153 ID that matches the user running BitBake. A match usually indicates
1154 that the files are being installed with an incorrect UID/GID, since
1155 target IDs are independent from host IDs. For additional information,
1156 see the section describing the
1157 :ref:`ref-tasks-install` task.
1158
1159- ``incompatible-license:`` Report when packages are excluded from
1160 being created due to being marked with a license that is in
1161 :term:`INCOMPATIBLE_LICENSE`.
1162
1163- ``install-host-path:`` Checks the
1164 :ref:`ref-tasks-install` log for indications that
1165 paths to locations on the build host were used. Using such paths
1166 might result in host contamination of the build output.
1167
1168- ``installed-vs-shipped:`` Reports when files have been installed
1169 within ``do_install`` but have not been included in any package by
1170 way of the :term:`FILES` variable. Files that do not
1171 appear in any package cannot be present in an image later on in the
1172 build process. Ideally, all installed files should be packaged or not
1173 installed at all. These files can be deleted at the end of
1174 ``do_install`` if the files are not needed in any package.
1175
1176- ``invalid-chars:`` Checks that the recipe metadata variables
1177 :term:`DESCRIPTION`,
1178 :term:`SUMMARY`, :term:`LICENSE`, and
1179 :term:`SECTION` do not contain non-UTF-8 characters.
1180 Some package managers do not support such characters.
1181
1182- ``invalid-packageconfig:`` Checks that no undefined features are
1183 being added to :term:`PACKAGECONFIG`. For
1184 example, any name "foo" for which the following form does not exist:
1185 ::
1186
1187 PACKAGECONFIG[foo] = "..."
1188
1189- ``la:`` Checks ``.la`` files for any ``TMPDIR`` paths. Any ``.la``
1190 file containing these paths is incorrect since ``libtool`` adds the
1191 correct sysroot prefix when using the files automatically itself.
1192
1193- ``ldflags:`` Ensures that the binaries were linked with the
1194 :term:`LDFLAGS` options provided by the build system.
1195 If this test fails, check that the ``LDFLAGS`` variable is being
1196 passed to the linker command.
1197
1198- ``libdir:`` Checks for libraries being installed into incorrect
1199 (possibly hardcoded) installation paths. For example, this test will
1200 catch recipes that install ``/lib/bar.so`` when ``${base_libdir}`` is
1201 "lib32". Another example is when recipes install
1202 ``/usr/lib64/foo.so`` when ``${libdir}`` is "/usr/lib".
1203
1204- ``libexec:`` Checks if a package contains files in
1205 ``/usr/libexec``. This check is not performed if the ``libexecdir``
1206 variable has been set explicitly to ``/usr/libexec``.
1207
1208- ``packages-list:`` Checks for the same package being listed
1209 multiple times through the :term:`PACKAGES` variable
1210 value. Installing the package in this manner can cause errors during
1211 packaging.
1212
1213- ``perm-config:`` Reports lines in ``fs-perms.txt`` that have an
1214 invalid format.
1215
1216- ``perm-line:`` Reports lines in ``fs-perms.txt`` that have an
1217 invalid format.
1218
1219- ``perm-link:`` Reports lines in ``fs-perms.txt`` that specify
1220 'link' where the specified target already exists.
1221
1222- ``perms:`` Currently, this check is unused but reserved.
1223
1224- ``pkgconfig:`` Checks ``.pc`` files for any
1225 :term:`TMPDIR`/:term:`WORKDIR` paths.
1226 Any ``.pc`` file containing these paths is incorrect since
1227 ``pkg-config`` itself adds the correct sysroot prefix when the files
1228 are accessed.
1229
1230- ``pkgname:`` Checks that all packages in
1231 :term:`PACKAGES` have names that do not contain
1232 invalid characters (i.e. characters other than 0-9, a-z, ., +, and
1233 -).
1234
1235- ``pkgv-undefined:`` Checks to see if the ``PKGV`` variable is
1236 undefined during :ref:`ref-tasks-package`.
1237
1238- ``pkgvarcheck:`` Checks through the variables
1239 :term:`RDEPENDS`,
1240 :term:`RRECOMMENDS`,
1241 :term:`RSUGGESTS`,
1242 :term:`RCONFLICTS`,
1243 :term:`RPROVIDES`,
1244 :term:`RREPLACES`, :term:`FILES`,
1245 :term:`ALLOW_EMPTY`, ``pkg_preinst``,
1246 ``pkg_postinst``, ``pkg_prerm`` and ``pkg_postrm``, and reports if
1247 there are variable sets that are not package-specific. Using these
1248 variables without a package suffix is bad practice, and might
1249 unnecessarily complicate dependencies of other packages within the
1250 same recipe or have other unintended consequences.
1251
1252- ``pn-overrides:`` Checks that a recipe does not have a name
1253 (:term:`PN`) value that appears in
1254 :term:`OVERRIDES`. If a recipe is named such that
1255 its ``PN`` value matches something already in ``OVERRIDES`` (e.g.
1256 ``PN`` happens to be the same as :term:`MACHINE` or
1257 :term:`DISTRO`), it can have unexpected consequences.
1258 For example, assignments such as ``FILES_${PN} = "xyz"`` effectively
1259 turn into ``FILES = "xyz"``.
1260
1261- ``rpaths:`` Checks for rpaths in the binaries that contain build
1262 system paths such as ``TMPDIR``. If this test fails, bad ``-rpath``
1263 options are being passed to the linker commands and your binaries
1264 have potential security issues.
1265
1266- ``split-strip:`` Reports that splitting or stripping debug symbols
1267 from binaries has failed.
1268
1269- ``staticdev:`` Checks for static library files (``*.a``) in
1270 non-``staticdev`` packages.
1271
1272- ``symlink-to-sysroot:`` Checks for symlinks in packages that point
1273 into :term:`TMPDIR` on the host. Such symlinks will
1274 work on the host, but are clearly invalid when running on the target.
1275
1276- ``textrel:`` Checks for ELF binaries that contain relocations in
1277 their ``.text`` sections, which can result in a performance impact at
Andrew Geissler4c19ea12020-10-27 13:52:24 -05001278 runtime. See the explanation for the ``ELF binary`` message in
1279 ":doc:`ref-qa-checks`" for more information regarding runtime performance
1280 issues.
Andrew Geisslerc9f78652020-09-18 14:11:35 -05001281
1282- ``unlisted-pkg-lics:`` Checks that all declared licenses applying
1283 for a package are also declared on the recipe level (i.e. any license
1284 in ``LICENSE_*`` should appear in :term:`LICENSE`).
1285
1286- ``useless-rpaths:`` Checks for dynamic library load paths (rpaths)
1287 in the binaries that by default on a standard system are searched by
1288 the linker (e.g. ``/lib`` and ``/usr/lib``). While these paths will
1289 not cause any breakage, they do waste space and are unnecessary.
1290
1291- ``var-undefined:`` Reports when variables fundamental to packaging
1292 (i.e. :term:`WORKDIR`,
1293 :term:`DEPLOY_DIR`, :term:`D`,
1294 :term:`PN`, and :term:`PKGD`) are undefined
1295 during :ref:`ref-tasks-package`.
1296
1297- ``version-going-backwards:`` If Build History is enabled, reports
1298 when a package being written out has a lower version than the
1299 previously written package under the same name. If you are placing
1300 output packages into a feed and upgrading packages on a target system
1301 using that feed, the version of a package going backwards can result
1302 in the target system not correctly upgrading to the "new" version of
1303 the package.
1304
1305 .. note::
1306
1307 If you are not using runtime package management on your target
1308 system, then you do not need to worry about this situation.
1309
1310- ``xorg-driver-abi:`` Checks that all packages containing Xorg
1311 drivers have ABI dependencies. The ``xserver-xorg`` recipe provides
1312 driver ABI names. All drivers should depend on the ABI versions that
1313 they have been built against. Driver recipes that include
1314 ``xorg-driver-input.inc`` or ``xorg-driver-video.inc`` will
1315 automatically get these versions. Consequently, you should only need
1316 to explicitly add dependencies to binary driver recipes.
1317
1318.. _ref-classes-insserv:
1319
1320``insserv.bbclass``
1321===================
1322
1323The ``insserv`` class uses the ``insserv`` utility to update the order
1324of symbolic links in ``/etc/rc?.d/`` within an image based on
1325dependencies specified by LSB headers in the ``init.d`` scripts
1326themselves.
1327
1328.. _ref-classes-kernel:
1329
1330``kernel.bbclass``
1331==================
1332
1333The ``kernel`` class handles building Linux kernels. The class contains
1334code to build all kernel trees. All needed headers are staged into the
1335``STAGING_KERNEL_DIR`` directory to allow out-of-tree module builds
1336using the :ref:`module <ref-classes-module>` class.
1337
1338This means that each built kernel module is packaged separately and
1339inter-module dependencies are created by parsing the ``modinfo`` output.
1340If all modules are required, then installing the ``kernel-modules``
1341package installs all packages with modules and various other kernel
1342packages such as ``kernel-vmlinux``.
1343
1344The ``kernel`` class contains logic that allows you to embed an initial
1345RAM filesystem (initramfs) image when you build the kernel image. For
1346information on how to build an initramfs, see the
1347":ref:`building-an-initramfs-image`" section in
1348the Yocto Project Development Tasks Manual.
1349
1350Various other classes are used by the ``kernel`` and ``module`` classes
1351internally including the :ref:`kernel-arch <ref-classes-kernel-arch>`,
1352:ref:`module-base <ref-classes-module-base>`, and
1353:ref:`linux-kernel-base <ref-classes-linux-kernel-base>` classes.
1354
1355.. _ref-classes-kernel-arch:
1356
1357``kernel-arch.bbclass``
1358=======================
1359
1360The ``kernel-arch`` class sets the ``ARCH`` environment variable for
1361Linux kernel compilation (including modules).
1362
1363.. _ref-classes-kernel-devicetree:
1364
1365``kernel-devicetree.bbclass``
1366=============================
1367
1368The ``kernel-devicetree`` class, which is inherited by the
1369:ref:`kernel <ref-classes-kernel>` class, supports device tree
1370generation.
1371
1372.. _ref-classes-kernel-fitimage:
1373
1374``kernel-fitimage.bbclass``
1375===========================
1376
1377The ``kernel-fitimage`` class provides support to pack a kernel Image,
1378device trees and a RAM disk into a single FIT image. In theory, a FIT
1379image can support any number of kernels, RAM disks and device-trees.
1380However, ``kernel-fitimage`` currently only supports
1381limited usescases: just one kernel image, an optional RAM disk, and
1382any number of device tree.
1383
1384To create a FIT image, it is required that :term:`KERNEL_CLASSES`
1385is set to "kernel-fitimage" and :term:`KERNEL_IMAGETYPE`
1386is set to "fitImage".
1387
1388The options for the device tree compiler passed to mkimage -D feature
1389when creating the FIT image are specified using the
1390:term:`UBOOT_MKIMAGE_DTCOPTS` variable.
1391
1392Only a single kernel can be added to the FIT image created by
1393``kernel-fitimage`` and the kernel image in FIT is mandatory. The
1394address where the kernel image is to be loaded by U-boot is
1395specified by :term:`UBOOT_LOADADDRESS` and the entrypoint by
1396:term:`UBOOT_ENTRYPOINT`.
1397
1398Multiple device trees can be added to the FIT image created by
1399``kernel-fitimage`` and the device tree is optional.
1400The address where the device tree is to be loaded by U-boot is
1401specified by :term:`UBOOT_DTBO_LOADADDRESS` for device tree overlays
Andrew Geissler4c19ea12020-10-27 13:52:24 -05001402and by :term:`UBOOT_DTB_LOADADDRESS` for device tree binaries.
Andrew Geisslerc9f78652020-09-18 14:11:35 -05001403
1404Only a single RAM disk can be added to the FIT image created by
1405``kernel-fitimage`` and the RAM disk in FIT is optional.
1406The address where the RAM disk image is to be loaded by U-boot
1407is specified by :term:`UBOOT_RD_LOADADDRESS` and the entrypoint by
1408:term:`UBOOT_RD_ENTRYPOINT`. The ramdisk is added to FIT image when
1409:term:`INITRAMFS_IMAGE` is specified.
1410
1411The FIT image generated by ``kernel-fitimage`` class is signed when the
1412variables :term:`UBOOT_SIGN_ENABLE`, :term:`UBOOT_MKIMAGE_DTCOPTS`,
1413:term:`UBOOT_SIGN_KEYDIR` and :term:`UBOOT_SIGN_KEYNAME` are set
1414appropriately. The default values used for :term:`FIT_HASH_ALG` and
1415:term:`FIT_SIGN_ALG` in ``kernel-fitimage`` are "sha256" and
Andrew Geisslerc3d88e42020-10-02 09:45:00 -05001416"rsa2048" respectively. The keys for signing fitImage can be generated using
1417the ``kernel-fitimage`` class when both :term:`FIT_GENERATE_KEYS` and
1418:term:`UBOOT_SIGN_ENABLE` are set to "1".
Andrew Geisslerc9f78652020-09-18 14:11:35 -05001419
1420
1421.. _ref-classes-kernel-grub:
1422
1423``kernel-grub.bbclass``
1424=======================
1425
1426The ``kernel-grub`` class updates the boot area and the boot menu with
1427the kernel as the priority boot mechanism while installing a RPM to
1428update the kernel on a deployed target.
1429
1430.. _ref-classes-kernel-module-split:
1431
1432``kernel-module-split.bbclass``
1433===============================
1434
1435The ``kernel-module-split`` class provides common functionality for
1436splitting Linux kernel modules into separate packages.
1437
1438.. _ref-classes-kernel-uboot:
1439
1440``kernel-uboot.bbclass``
1441========================
1442
1443The ``kernel-uboot`` class provides support for building from
1444vmlinux-style kernel sources.
1445
1446.. _ref-classes-kernel-uimage:
1447
1448``kernel-uimage.bbclass``
1449=========================
1450
1451The ``kernel-uimage`` class provides support to pack uImage.
1452
1453.. _ref-classes-kernel-yocto:
1454
1455``kernel-yocto.bbclass``
1456========================
1457
1458The ``kernel-yocto`` class provides common functionality for building
1459from linux-yocto style kernel source repositories.
1460
1461.. _ref-classes-kernelsrc:
1462
1463``kernelsrc.bbclass``
1464=====================
1465
1466The ``kernelsrc`` class sets the Linux kernel source and version.
1467
1468.. _ref-classes-lib_package:
1469
1470``lib_package.bbclass``
1471=======================
1472
1473The ``lib_package`` class supports recipes that build libraries and
1474produce executable binaries, where those binaries should not be
1475installed by default along with the library. Instead, the binaries are
1476added to a separate ``${``\ :term:`PN`\ ``}-bin`` package to
1477make their installation optional.
1478
1479.. _ref-classes-libc*:
1480
1481``libc*.bbclass``
1482=================
1483
1484The ``libc*`` classes support recipes that build packages with ``libc``:
1485
1486- The ``libc-common`` class provides common support for building with
1487 ``libc``.
1488
1489- The ``libc-package`` class supports packaging up ``glibc`` and
1490 ``eglibc``.
1491
1492.. _ref-classes-license:
1493
1494``license.bbclass``
1495===================
1496
1497The ``license`` class provides license manifest creation and license
1498exclusion. This class is enabled by default using the default value for
1499the :term:`INHERIT_DISTRO` variable.
1500
1501.. _ref-classes-linux-kernel-base:
1502
1503``linux-kernel-base.bbclass``
1504=============================
1505
1506The ``linux-kernel-base`` class provides common functionality for
1507recipes that build out of the Linux kernel source tree. These builds
1508goes beyond the kernel itself. For example, the Perf recipe also
1509inherits this class.
1510
1511.. _ref-classes-linuxloader:
1512
1513``linuxloader.bbclass``
1514=======================
1515
1516Provides the function ``linuxloader()``, which gives the value of the
1517dynamic loader/linker provided on the platform. This value is used by a
1518number of other classes.
1519
1520.. _ref-classes-logging:
1521
1522``logging.bbclass``
1523===================
1524
1525The ``logging`` class provides the standard shell functions used to log
1526messages for various BitBake severity levels (i.e. ``bbplain``,
1527``bbnote``, ``bbwarn``, ``bberror``, ``bbfatal``, and ``bbdebug``).
1528
1529This class is enabled by default since it is inherited by the ``base``
1530class.
1531
1532.. _ref-classes-meta:
1533
1534``meta.bbclass``
1535================
1536
1537The ``meta`` class is inherited by recipes that do not build any output
1538packages themselves, but act as a "meta" target for building other
1539recipes.
1540
1541.. _ref-classes-metadata_scm:
1542
1543``metadata_scm.bbclass``
1544========================
1545
1546The ``metadata_scm`` class provides functionality for querying the
1547branch and revision of a Source Code Manager (SCM) repository.
1548
1549The :ref:`base <ref-classes-base>` class uses this class to print the
1550revisions of each layer before starting every build. The
1551``metadata_scm`` class is enabled by default because it is inherited by
1552the ``base`` class.
1553
1554.. _ref-classes-migrate_localcount:
1555
1556``migrate_localcount.bbclass``
1557==============================
1558
1559The ``migrate_localcount`` class verifies a recipe's localcount data and
1560increments it appropriately.
1561
1562.. _ref-classes-mime:
1563
1564``mime.bbclass``
1565================
1566
1567The ``mime`` class generates the proper post-install and post-remove
1568(postinst/postrm) scriptlets for packages that install MIME type files.
1569These scriptlets call ``update-mime-database`` to add the MIME types to
1570the shared database.
1571
1572.. _ref-classes-mirrors:
1573
1574``mirrors.bbclass``
1575===================
1576
1577The ``mirrors`` class sets up some standard
1578:term:`MIRRORS` entries for source code mirrors. These
1579mirrors provide a fall-back path in case the upstream source specified
1580in :term:`SRC_URI` within recipes is unavailable.
1581
1582This class is enabled by default since it is inherited by the
1583:ref:`base <ref-classes-base>` class.
1584
1585.. _ref-classes-module:
1586
1587``module.bbclass``
1588==================
1589
1590The ``module`` class provides support for building out-of-tree Linux
1591kernel modules. The class inherits the
1592:ref:`module-base <ref-classes-module-base>` and
1593:ref:`kernel-module-split <ref-classes-kernel-module-split>` classes,
1594and implements the :ref:`ref-tasks-compile` and
1595:ref:`ref-tasks-install` tasks. The class provides
1596everything needed to build and package a kernel module.
1597
1598For general information on out-of-tree Linux kernel modules, see the
1599":ref:`kernel-dev/kernel-dev-common:incorporating out-of-tree modules`"
1600section in the Yocto Project Linux Kernel Development Manual.
1601
1602.. _ref-classes-module-base:
1603
1604``module-base.bbclass``
1605=======================
1606
1607The ``module-base`` class provides the base functionality for building
1608Linux kernel modules. Typically, a recipe that builds software that
1609includes one or more kernel modules and has its own means of building
1610the module inherits this class as opposed to inheriting the
1611:ref:`module <ref-classes-module>` class.
1612
1613.. _ref-classes-multilib*:
1614
1615``multilib*.bbclass``
1616=====================
1617
1618The ``multilib*`` classes provide support for building libraries with
1619different target optimizations or target architectures and installing
1620them side-by-side in the same image.
1621
1622For more information on using the Multilib feature, see the
1623":ref:`combining-multiple-versions-library-files-into-one-image`"
1624section in the Yocto Project Development Tasks Manual.
1625
1626.. _ref-classes-native:
1627
1628``native.bbclass``
1629==================
1630
1631The ``native`` class provides common functionality for recipes that
Andrew Geissler4c19ea12020-10-27 13:52:24 -05001632build tools to run on the :term:`Build Host` (i.e. tools that use the compiler
1633or other tools from the build host).
Andrew Geisslerc9f78652020-09-18 14:11:35 -05001634
1635You can create a recipe that builds tools that run natively on the host
1636a couple different ways:
1637
1638- Create a myrecipe\ ``-native.bb`` recipe that inherits the ``native``
1639 class. If you use this method, you must order the inherit statement
1640 in the recipe after all other inherit statements so that the
1641 ``native`` class is inherited last.
1642
1643 .. note::
1644
1645 When creating a recipe this way, the recipe name must follow this
1646 naming convention:
1647 ::
1648
1649 myrecipe-native.bb
1650
1651
1652 Not using this naming convention can lead to subtle problems
1653 caused by existing code that depends on that naming convention.
1654
1655- Create or modify a target recipe that contains the following:
1656 ::
1657
1658 BBCLASSEXTEND = "native"
1659
1660 Inside the
1661 recipe, use ``_class-native`` and ``_class-target`` overrides to
1662 specify any functionality specific to the respective native or target
1663 case.
1664
1665Although applied differently, the ``native`` class is used with both
1666methods. The advantage of the second method is that you do not need to
1667have two separate recipes (assuming you need both) for native and
1668target. All common parts of the recipe are automatically shared.
1669
1670.. _ref-classes-nativesdk:
1671
1672``nativesdk.bbclass``
1673=====================
1674
1675The ``nativesdk`` class provides common functionality for recipes that
1676wish to build tools to run as part of an SDK (i.e. tools that run on
1677:term:`SDKMACHINE`).
1678
1679You can create a recipe that builds tools that run on the SDK machine a
1680couple different ways:
1681
1682- Create a ``nativesdk-``\ myrecipe\ ``.bb`` recipe that inherits the
1683 ``nativesdk`` class. If you use this method, you must order the
1684 inherit statement in the recipe after all other inherit statements so
1685 that the ``nativesdk`` class is inherited last.
1686
1687- Create a ``nativesdk`` variant of any recipe by adding the following:
1688 ::
1689
1690 BBCLASSEXTEND = "nativesdk"
1691
1692 Inside the
1693 recipe, use ``_class-nativesdk`` and ``_class-target`` overrides to
1694 specify any functionality specific to the respective SDK machine or
1695 target case.
1696
1697.. note::
1698
1699 When creating a recipe, you must follow this naming convention:
1700 ::
1701
1702 nativesdk-myrecipe.bb
1703
1704
1705 Not doing so can lead to subtle problems because code exists that
1706 depends on the naming convention.
1707
1708Although applied differently, the ``nativesdk`` class is used with both
1709methods. The advantage of the second method is that you do not need to
1710have two separate recipes (assuming you need both) for the SDK machine
1711and the target. All common parts of the recipe are automatically shared.
1712
1713.. _ref-classes-nopackages:
1714
1715``nopackages.bbclass``
1716======================
1717
1718Disables packaging tasks for those recipes and classes where packaging
1719is not needed.
1720
1721.. _ref-classes-npm:
1722
1723``npm.bbclass``
1724===============
1725
1726Provides support for building Node.js software fetched using the `node
1727package manager (NPM) <https://en.wikipedia.org/wiki/Npm_(software)>`__.
1728
1729.. note::
1730
Andrew Geissler4c19ea12020-10-27 13:52:24 -05001731 Currently, recipes inheriting this class must use the ``npm://``
Andrew Geisslerc9f78652020-09-18 14:11:35 -05001732 fetcher to have dependencies fetched and packaged automatically.
1733
1734For information on how to create NPM packages, see the
1735":ref:`dev-manual/dev-manual-common-tasks:creating node package manager (npm) packages`"
1736section in the Yocto Project Development Tasks Manual.
1737
1738.. _ref-classes-oelint:
1739
1740``oelint.bbclass``
1741==================
1742
1743The ``oelint`` class is an obsolete lint checking tool that exists in
1744``meta/classes`` in the :term:`Source Directory`.
1745
1746A number of classes exist that could be generally useful in OE-Core but
1747are never actually used within OE-Core itself. The ``oelint`` class is
1748one such example. However, being aware of this class can reduce the
1749proliferation of different versions of similar classes across multiple
1750layers.
1751
1752.. _ref-classes-own-mirrors:
1753
1754``own-mirrors.bbclass``
1755=======================
1756
1757The ``own-mirrors`` class makes it easier to set up your own
1758:term:`PREMIRRORS` from which to first fetch source
1759before attempting to fetch it from the upstream specified in
1760:term:`SRC_URI` within each recipe.
1761
1762To use this class, inherit it globally and specify
1763:term:`SOURCE_MIRROR_URL`. Here is an example:
1764::
1765
1766 INHERIT += "own-mirrors"
1767 SOURCE_MIRROR_URL = "http://example.com/my-source-mirror"
1768
1769You can specify only a single URL
1770in ``SOURCE_MIRROR_URL``.
1771
1772.. _ref-classes-package:
1773
1774``package.bbclass``
1775===================
1776
1777The ``package`` class supports generating packages from a build's
1778output. The core generic functionality is in ``package.bbclass``. The
1779code specific to particular package types resides in these
1780package-specific classes:
1781:ref:`package_deb <ref-classes-package_deb>`,
1782:ref:`package_rpm <ref-classes-package_rpm>`,
1783:ref:`package_ipk <ref-classes-package_ipk>`, and
1784:ref:`package_tar <ref-classes-package_tar>`.
1785
1786.. note::
1787
1788 The
1789 package_tar
1790 class is broken and not supported. It is recommended that you do not
1791 use this class.
1792
1793You can control the list of resulting package formats by using the
1794``PACKAGE_CLASSES`` variable defined in your ``conf/local.conf``
1795configuration file, which is located in the :term:`Build Directory`.
1796When defining the variable, you can
1797specify one or more package types. Since images are generated from
1798packages, a packaging class is needed to enable image generation. The
1799first class listed in this variable is used for image generation.
1800
1801If you take the optional step to set up a repository (package feed) on
1802the development host that can be used by DNF, you can install packages
1803from the feed while you are running the image on the target (i.e.
1804runtime installation of packages). For more information, see the
1805":ref:`dev-manual/dev-manual-common-tasks:using runtime package management`"
1806section in the Yocto Project Development Tasks Manual.
1807
1808The package-specific class you choose can affect build-time performance
1809and has space ramifications. In general, building a package with IPK
1810takes about thirty percent less time as compared to using RPM to build
1811the same or similar package. This comparison takes into account a
1812complete build of the package with all dependencies previously built.
1813The reason for this discrepancy is because the RPM package manager
1814creates and processes more :term:`Metadata` than the IPK package
1815manager. Consequently, you might consider setting ``PACKAGE_CLASSES`` to
1816"package_ipk" if you are building smaller systems.
1817
1818Before making your package manager decision, however, you should
1819consider some further things about using RPM:
1820
1821- RPM starts to provide more abilities than IPK due to the fact that it
1822 processes more Metadata. For example, this information includes
1823 individual file types, file checksum generation and evaluation on
1824 install, sparse file support, conflict detection and resolution for
1825 Multilib systems, ACID style upgrade, and repackaging abilities for
1826 rollbacks.
1827
1828- For smaller systems, the extra space used for the Berkeley Database
1829 and the amount of metadata when using RPM can affect your ability to
1830 perform on-device upgrades.
1831
1832You can find additional information on the effects of the package class
1833at these two Yocto Project mailing list links:
1834
Andrew Geissler4c19ea12020-10-27 13:52:24 -05001835- :yocto_lists:`/pipermail/poky/2011-May/006362.html`
Andrew Geisslerc9f78652020-09-18 14:11:35 -05001836
Andrew Geissler4c19ea12020-10-27 13:52:24 -05001837- :yocto_lists:`/pipermail/poky/2011-May/006363.html`
Andrew Geisslerc9f78652020-09-18 14:11:35 -05001838
1839.. _ref-classes-package_deb:
1840
1841``package_deb.bbclass``
1842=======================
1843
1844The ``package_deb`` class provides support for creating packages that
1845use the Debian (i.e. ``.deb``) file format. The class ensures the
1846packages are written out in a ``.deb`` file format to the
1847``${``\ :term:`DEPLOY_DIR_DEB`\ ``}`` directory.
1848
1849This class inherits the :ref:`package <ref-classes-package>` class and
1850is enabled through the :term:`PACKAGE_CLASSES`
1851variable in the ``local.conf`` file.
1852
1853.. _ref-classes-package_ipk:
1854
1855``package_ipk.bbclass``
1856=======================
1857
1858The ``package_ipk`` class provides support for creating packages that
1859use the IPK (i.e. ``.ipk``) file format. The class ensures the packages
1860are written out in a ``.ipk`` file format to the
1861``${``\ :term:`DEPLOY_DIR_IPK`\ ``}`` directory.
1862
1863This class inherits the :ref:`package <ref-classes-package>` class and
1864is enabled through the :term:`PACKAGE_CLASSES`
1865variable in the ``local.conf`` file.
1866
1867.. _ref-classes-package_rpm:
1868
1869``package_rpm.bbclass``
1870=======================
1871
1872The ``package_rpm`` class provides support for creating packages that
1873use the RPM (i.e. ``.rpm``) file format. The class ensures the packages
1874are written out in a ``.rpm`` file format to the
1875``${``\ :term:`DEPLOY_DIR_RPM`\ ``}`` directory.
1876
1877This class inherits the :ref:`package <ref-classes-package>` class and
1878is enabled through the :term:`PACKAGE_CLASSES`
1879variable in the ``local.conf`` file.
1880
1881.. _ref-classes-package_tar:
1882
1883``package_tar.bbclass``
1884=======================
1885
1886The ``package_tar`` class provides support for creating tarballs. The
1887class ensures the packages are written out in a tarball format to the
1888``${``\ :term:`DEPLOY_DIR_TAR`\ ``}`` directory.
1889
1890This class inherits the :ref:`package <ref-classes-package>` class and
1891is enabled through the :term:`PACKAGE_CLASSES`
1892variable in the ``local.conf`` file.
1893
1894.. note::
1895
Andrew Geissler4c19ea12020-10-27 13:52:24 -05001896 You cannot specify the ``package_tar`` class first using the
1897 ``PACKAGE_CLASSES`` variable. You must use ``.deb``, ``.ipk``, or ``.rpm``
Andrew Geisslerc9f78652020-09-18 14:11:35 -05001898 file formats for your image or SDK.
1899
1900.. _ref-classes-packagedata:
1901
1902``packagedata.bbclass``
1903=======================
1904
1905The ``packagedata`` class provides common functionality for reading
1906``pkgdata`` files found in :term:`PKGDATA_DIR`. These
1907files contain information about each output package produced by the
1908OpenEmbedded build system.
1909
1910This class is enabled by default because it is inherited by the
1911:ref:`package <ref-classes-package>` class.
1912
1913.. _ref-classes-packagegroup:
1914
1915``packagegroup.bbclass``
1916========================
1917
1918The ``packagegroup`` class sets default values appropriate for package
1919group recipes (e.g. ``PACKAGES``, ``PACKAGE_ARCH``, ``ALLOW_EMPTY``, and
1920so forth). It is highly recommended that all package group recipes
1921inherit this class.
1922
1923For information on how to use this class, see the
1924":ref:`usingpoky-extend-customimage-customtasks`"
1925section in the Yocto Project Development Tasks Manual.
1926
1927Previously, this class was called the ``task`` class.
1928
1929.. _ref-classes-patch:
1930
1931``patch.bbclass``
1932=================
1933
1934The ``patch`` class provides all functionality for applying patches
1935during the :ref:`ref-tasks-patch` task.
1936
1937This class is enabled by default because it is inherited by the
1938:ref:`base <ref-classes-base>` class.
1939
1940.. _ref-classes-perlnative:
1941
1942``perlnative.bbclass``
1943======================
1944
1945When inherited by a recipe, the ``perlnative`` class supports using the
1946native version of Perl built by the build system rather than using the
1947version provided by the build host.
1948
1949.. _ref-classes-pixbufcache:
1950
1951``pixbufcache.bbclass``
1952=======================
1953
1954The ``pixbufcache`` class generates the proper post-install and
1955post-remove (postinst/postrm) scriptlets for packages that install
1956pixbuf loaders, which are used with ``gdk-pixbuf``. These scriptlets
1957call ``update_pixbuf_cache`` to add the pixbuf loaders to the cache.
1958Since the cache files are architecture-specific, ``update_pixbuf_cache``
1959is run using QEMU if the postinst scriptlets need to be run on the build
1960host during image creation.
1961
1962If the pixbuf loaders being installed are in packages other than the
1963recipe's main package, set
1964:term:`PIXBUF_PACKAGES` to specify the packages
1965containing the loaders.
1966
1967.. _ref-classes-pkgconfig:
1968
1969``pkgconfig.bbclass``
1970=====================
1971
1972The ``pkgconfig`` class provides a standard way to get header and
1973library information by using ``pkg-config``. This class aims to smooth
1974integration of ``pkg-config`` into libraries that use it.
1975
1976During staging, BitBake installs ``pkg-config`` data into the
1977``sysroots/`` directory. By making use of sysroot functionality within
1978``pkg-config``, the ``pkgconfig`` class no longer has to manipulate the
1979files.
1980
1981.. _ref-classes-populate-sdk:
1982
1983``populate_sdk.bbclass``
1984========================
1985
1986The ``populate_sdk`` class provides support for SDK-only recipes. For
1987information on advantages gained when building a cross-development
1988toolchain using the :ref:`ref-tasks-populate_sdk`
1989task, see the ":ref:`sdk-manual/sdk-appendix-obtain:building an sdk installer`"
1990section in the Yocto Project Application Development and the Extensible
1991Software Development Kit (eSDK) manual.
1992
1993.. _ref-classes-populate-sdk-*:
1994
1995``populate_sdk_*.bbclass``
1996==========================
1997
1998The ``populate_sdk_*`` classes support SDK creation and consist of the
1999following classes:
2000
2001- ``populate_sdk_base``: The base class supporting SDK creation under
2002 all package managers (i.e. DEB, RPM, and opkg).
2003
2004- ``populate_sdk_deb``: Supports creation of the SDK given the Debian
2005 package manager.
2006
2007- ``populate_sdk_rpm``: Supports creation of the SDK given the RPM
2008 package manager.
2009
2010- ``populate_sdk_ipk``: Supports creation of the SDK given the opkg
2011 (IPK format) package manager.
2012
2013- ``populate_sdk_ext``: Supports extensible SDK creation under all
2014 package managers.
2015
2016The ``populate_sdk_base`` class inherits the appropriate
2017``populate_sdk_*`` (i.e. ``deb``, ``rpm``, and ``ipk``) based on
2018:term:`IMAGE_PKGTYPE`.
2019
2020The base class ensures all source and destination directories are
2021established and then populates the SDK. After populating the SDK, the
2022``populate_sdk_base`` class constructs two sysroots:
2023``${``\ :term:`SDK_ARCH`\ ``}-nativesdk``, which
2024contains the cross-compiler and associated tooling, and the target,
2025which contains a target root filesystem that is configured for the SDK
2026usage. These two images reside in :term:`SDK_OUTPUT`,
2027which consists of the following:
2028::
2029
2030 ${SDK_OUTPUT}/${SDK_ARCH}-nativesdk-pkgs
2031 ${SDK_OUTPUT}/${SDKTARGETSYSROOT}/target-pkgs
2032
2033Finally, the base populate SDK class creates the toolchain environment
2034setup script, the tarball of the SDK, and the installer.
2035
2036The respective ``populate_sdk_deb``, ``populate_sdk_rpm``, and
2037``populate_sdk_ipk`` classes each support the specific type of SDK.
2038These classes are inherited by and used with the ``populate_sdk_base``
2039class.
2040
2041For more information on the cross-development toolchain generation, see
2042the ":ref:`overview-manual/overview-manual-concepts:cross-development toolchain generation`"
2043section in the Yocto Project Overview and Concepts Manual. For
2044information on advantages gained when building a cross-development
2045toolchain using the :ref:`ref-tasks-populate_sdk`
2046task, see the
2047":ref:`sdk-manual/sdk-appendix-obtain:building an sdk installer`"
2048section in the Yocto Project Application Development and the Extensible
2049Software Development Kit (eSDK) manual.
2050
2051.. _ref-classes-prexport:
2052
2053``prexport.bbclass``
2054====================
2055
2056The ``prexport`` class provides functionality for exporting
2057:term:`PR` values.
2058
2059.. note::
2060
2061 This class is not intended to be used directly. Rather, it is enabled
Andrew Geissler4c19ea12020-10-27 13:52:24 -05002062 when using "``bitbake-prserv-tool export``".
Andrew Geisslerc9f78652020-09-18 14:11:35 -05002063
2064.. _ref-classes-primport:
2065
2066``primport.bbclass``
2067====================
2068
2069The ``primport`` class provides functionality for importing
2070:term:`PR` values.
2071
2072.. note::
2073
2074 This class is not intended to be used directly. Rather, it is enabled
Andrew Geissler4c19ea12020-10-27 13:52:24 -05002075 when using "``bitbake-prserv-tool import``".
Andrew Geisslerc9f78652020-09-18 14:11:35 -05002076
2077.. _ref-classes-prserv:
2078
2079``prserv.bbclass``
2080==================
2081
2082The ``prserv`` class provides functionality for using a :ref:`PR
2083service <dev-manual/dev-manual-common-tasks:working with a pr service>` in order to
2084automatically manage the incrementing of the :term:`PR`
2085variable for each recipe.
2086
2087This class is enabled by default because it is inherited by the
2088:ref:`package <ref-classes-package>` class. However, the OpenEmbedded
2089build system will not enable the functionality of this class unless
2090:term:`PRSERV_HOST` has been set.
2091
2092.. _ref-classes-ptest:
2093
2094``ptest.bbclass``
2095=================
2096
2097The ``ptest`` class provides functionality for packaging and installing
2098runtime tests for recipes that build software that provides these tests.
2099
2100This class is intended to be inherited by individual recipes. However,
2101the class' functionality is largely disabled unless "ptest" appears in
2102:term:`DISTRO_FEATURES`. See the
2103":ref:`dev-manual/dev-manual-common-tasks:testing packages with ptest`"
2104section in the Yocto Project Development Tasks Manual for more information
2105on ptest.
2106
2107.. _ref-classes-ptest-gnome:
2108
2109``ptest-gnome.bbclass``
2110=======================
2111
2112Enables package tests (ptests) specifically for GNOME packages, which
2113have tests intended to be executed with ``gnome-desktop-testing``.
2114
2115For information on setting up and running ptests, see the
2116":ref:`dev-manual/dev-manual-common-tasks:testing packages with ptest`"
2117section in the Yocto Project Development Tasks Manual.
2118
2119.. _ref-classes-python-dir:
2120
2121``python-dir.bbclass``
2122======================
2123
2124The ``python-dir`` class provides the base version, location, and site
2125package location for Python.
2126
2127.. _ref-classes-python3native:
2128
2129``python3native.bbclass``
2130=========================
2131
2132The ``python3native`` class supports using the native version of Python
21333 built by the build system rather than support of the version provided
2134by the build host.
2135
2136.. _ref-classes-pythonnative:
2137
2138``pythonnative.bbclass``
2139========================
2140
2141When inherited by a recipe, the ``pythonnative`` class supports using
2142the native version of Python built by the build system rather than using
2143the version provided by the build host.
2144
2145.. _ref-classes-qemu:
2146
2147``qemu.bbclass``
2148================
2149
2150The ``qemu`` class provides functionality for recipes that either need
2151QEMU or test for the existence of QEMU. Typically, this class is used to
2152run programs for a target system on the build host using QEMU's
2153application emulation mode.
2154
2155.. _ref-classes-recipe_sanity:
2156
2157``recipe_sanity.bbclass``
2158=========================
2159
2160The ``recipe_sanity`` class checks for the presence of any host system
2161recipe prerequisites that might affect the build (e.g. variables that
2162are set or software that is present).
2163
2164.. _ref-classes-relocatable:
2165
2166``relocatable.bbclass``
2167=======================
2168
2169The ``relocatable`` class enables relocation of binaries when they are
2170installed into the sysroot.
2171
2172This class makes use of the :ref:`chrpath <ref-classes-chrpath>` class
2173and is used by both the :ref:`cross <ref-classes-cross>` and
2174:ref:`native <ref-classes-native>` classes.
2175
2176.. _ref-classes-remove-libtool:
2177
2178``remove-libtool.bbclass``
2179==========================
2180
2181The ``remove-libtool`` class adds a post function to the
2182:ref:`ref-tasks-install` task to remove all ``.la`` files
2183installed by ``libtool``. Removing these files results in them being
2184absent from both the sysroot and target packages.
2185
2186If a recipe needs the ``.la`` files to be installed, then the recipe can
2187override the removal by setting ``REMOVE_LIBTOOL_LA`` to "0" as follows:
2188::
2189
2190 REMOVE_LIBTOOL_LA = "0"
2191
2192.. note::
2193
Andrew Geissler4c19ea12020-10-27 13:52:24 -05002194 The ``remove-libtool`` class is not enabled by default.
Andrew Geisslerc9f78652020-09-18 14:11:35 -05002195
2196.. _ref-classes-report-error:
2197
2198``report-error.bbclass``
2199========================
2200
2201The ``report-error`` class supports enabling the :ref:`error reporting
2202tool <dev-manual/dev-manual-common-tasks:using the error reporting tool>`",
2203which allows you to submit build error information to a central database.
2204
2205The class collects debug information for recipe, recipe version, task,
2206machine, distro, build system, target system, host distro, branch,
2207commit, and log. From the information, report files using a JSON format
2208are created and stored in
2209``${``\ :term:`LOG_DIR`\ ``}/error-report``.
2210
2211.. _ref-classes-rm-work:
2212
2213``rm_work.bbclass``
2214===================
2215
2216The ``rm_work`` class supports deletion of temporary workspace, which
2217can ease your hard drive demands during builds.
2218
2219The OpenEmbedded build system can use a substantial amount of disk space
2220during the build process. A portion of this space is the work files
2221under the ``${TMPDIR}/work`` directory for each recipe. Once the build
2222system generates the packages for a recipe, the work files for that
2223recipe are no longer needed. However, by default, the build system
2224preserves these files for inspection and possible debugging purposes. If
2225you would rather have these files deleted to save disk space as the
2226build progresses, you can enable ``rm_work`` by adding the following to
2227your ``local.conf`` file, which is found in the :term:`Build Directory`.
2228::
2229
2230 INHERIT += "rm_work"
2231
2232If you are
2233modifying and building source code out of the work directory for a
2234recipe, enabling ``rm_work`` will potentially result in your changes to
2235the source being lost. To exclude some recipes from having their work
2236directories deleted by ``rm_work``, you can add the names of the recipe
2237or recipes you are working on to the ``RM_WORK_EXCLUDE`` variable, which
2238can also be set in your ``local.conf`` file. Here is an example:
2239::
2240
2241 RM_WORK_EXCLUDE += "busybox glibc"
2242
2243.. _ref-classes-rootfs*:
2244
2245``rootfs*.bbclass``
2246===================
2247
2248The ``rootfs*`` classes support creating the root filesystem for an
2249image and consist of the following classes:
2250
2251- The ``rootfs-postcommands`` class, which defines filesystem
2252 post-processing functions for image recipes.
2253
2254- The ``rootfs_deb`` class, which supports creation of root filesystems
2255 for images built using ``.deb`` packages.
2256
2257- The ``rootfs_rpm`` class, which supports creation of root filesystems
2258 for images built using ``.rpm`` packages.
2259
2260- The ``rootfs_ipk`` class, which supports creation of root filesystems
2261 for images built using ``.ipk`` packages.
2262
2263- The ``rootfsdebugfiles`` class, which installs additional files found
2264 on the build host directly into the root filesystem.
2265
2266The root filesystem is created from packages using one of the
2267``rootfs*.bbclass`` files as determined by the
2268:term:`PACKAGE_CLASSES` variable.
2269
2270For information on how root filesystem images are created, see the
Andrew Geissler4c19ea12020-10-27 13:52:24 -05002271":ref:`image-generation-dev-environment`"
Andrew Geisslerc9f78652020-09-18 14:11:35 -05002272section in the Yocto Project Overview and Concepts Manual.
2273
2274.. _ref-classes-sanity:
2275
2276``sanity.bbclass``
2277==================
2278
2279The ``sanity`` class checks to see if prerequisite software is present
2280on the host system so that users can be notified of potential problems
2281that might affect their build. The class also performs basic user
2282configuration checks from the ``local.conf`` configuration file to
2283prevent common mistakes that cause build failures. Distribution policy
2284usually determines whether to include this class.
2285
2286.. _ref-classes-scons:
2287
2288``scons.bbclass``
2289=================
2290
2291The ``scons`` class supports recipes that need to build software that
2292uses the SCons build system. You can use the
2293:term:`EXTRA_OESCONS` variable to specify
2294additional configuration options you want to pass SCons command line.
2295
2296.. _ref-classes-sdl:
2297
2298``sdl.bbclass``
2299===============
2300
2301The ``sdl`` class supports recipes that need to build software that uses
2302the Simple DirectMedia Layer (SDL) library.
2303
2304.. _ref-classes-setuptools:
2305
2306``setuptools.bbclass``
2307======================
2308
2309The ``setuptools`` class supports Python version 2.x extensions that use
2310build systems based on ``setuptools``. If your recipe uses these build
2311systems, the recipe needs to inherit the ``setuptools`` class.
2312
2313.. _ref-classes-setuptools3:
2314
2315``setuptools3.bbclass``
2316=======================
2317
2318The ``setuptools3`` class supports Python version 3.x extensions that
2319use build systems based on ``setuptools3``. If your recipe uses these
2320build systems, the recipe needs to inherit the ``setuptools3`` class.
2321
2322.. _ref-classes-sign_rpm:
2323
2324``sign_rpm.bbclass``
2325====================
2326
2327The ``sign_rpm`` class supports generating signed RPM packages.
2328
2329.. _ref-classes-sip:
2330
2331``sip.bbclass``
2332===============
2333
2334The ``sip`` class supports recipes that build or package SIP-based
2335Python bindings.
2336
2337.. _ref-classes-siteconfig:
2338
2339``siteconfig.bbclass``
2340======================
2341
2342The ``siteconfig`` class provides functionality for handling site
2343configuration. The class is used by the
2344:ref:`autotools <ref-classes-autotools>` class to accelerate the
2345:ref:`ref-tasks-configure` task.
2346
2347.. _ref-classes-siteinfo:
2348
2349``siteinfo.bbclass``
2350====================
2351
2352The ``siteinfo`` class provides information about the targets that might
2353be needed by other classes or recipes.
2354
2355As an example, consider Autotools, which can require tests that must
2356execute on the target hardware. Since this is not possible in general
2357when cross compiling, site information is used to provide cached test
2358results so these tests can be skipped over but still make the correct
2359values available. The ``meta/site directory`` contains test results
2360sorted into different categories such as architecture, endianness, and
2361the ``libc`` used. Site information provides a list of files containing
2362data relevant to the current build in the ``CONFIG_SITE`` variable that
2363Autotools automatically picks up.
2364
2365The class also provides variables like ``SITEINFO_ENDIANNESS`` and
2366``SITEINFO_BITS`` that can be used elsewhere in the metadata.
2367
Andrew Geisslerc9f78652020-09-18 14:11:35 -05002368.. _ref-classes-sstate:
2369
2370``sstate.bbclass``
2371==================
2372
2373The ``sstate`` class provides support for Shared State (sstate). By
2374default, the class is enabled through the
2375:term:`INHERIT_DISTRO` variable's default value.
2376
2377For more information on sstate, see the
2378":ref:`overview-manual/overview-manual-concepts:shared state cache`"
2379section in the Yocto Project Overview and Concepts Manual.
2380
2381.. _ref-classes-staging:
2382
2383``staging.bbclass``
2384===================
2385
2386The ``staging`` class installs files into individual recipe work
2387directories for sysroots. The class contains the following key tasks:
2388
2389- The :ref:`ref-tasks-populate_sysroot` task,
2390 which is responsible for handing the files that end up in the recipe
2391 sysroots.
2392
2393- The
2394 :ref:`ref-tasks-prepare_recipe_sysroot`
2395 task (a "partner" task to the ``populate_sysroot`` task), which
2396 installs the files into the individual recipe work directories (i.e.
2397 :term:`WORKDIR`).
2398
2399The code in the ``staging`` class is complex and basically works in two
2400stages:
2401
2402- *Stage One:* The first stage addresses recipes that have files they
2403 want to share with other recipes that have dependencies on the
2404 originating recipe. Normally these dependencies are installed through
2405 the :ref:`ref-tasks-install` task into
2406 ``${``\ :term:`D`\ ``}``. The ``do_populate_sysroot`` task
2407 copies a subset of these files into ``${SYSROOT_DESTDIR}``. This
2408 subset of files is controlled by the
2409 :term:`SYSROOT_DIRS`,
2410 :term:`SYSROOT_DIRS_NATIVE`, and
2411 :term:`SYSROOT_DIRS_BLACKLIST`
2412 variables.
2413
2414 .. note::
2415
2416 Additionally, a recipe can customize the files further by
Andrew Geissler4c19ea12020-10-27 13:52:24 -05002417 declaring a processing function in the ``SYSROOT_PREPROCESS_FUNCS``
Andrew Geisslerc9f78652020-09-18 14:11:35 -05002418 variable.
2419
2420 A shared state (sstate) object is built from these files and the
2421 files are placed into a subdirectory of
Andrew Geissler4c19ea12020-10-27 13:52:24 -05002422 :ref:`structure-build-tmp-sysroots-components`.
Andrew Geisslerc9f78652020-09-18 14:11:35 -05002423 The files are scanned for hardcoded paths to the original
2424 installation location. If the location is found in text files, the
2425 hardcoded locations are replaced by tokens and a list of the files
2426 needing such replacements is created. These adjustments are referred
2427 to as "FIXMEs". The list of files that are scanned for paths is
2428 controlled by the :term:`SSTATE_SCAN_FILES`
2429 variable.
2430
2431- *Stage Two:* The second stage addresses recipes that want to use
2432 something from another recipe and declare a dependency on that recipe
2433 through the :term:`DEPENDS` variable. The recipe will
2434 have a
2435 :ref:`ref-tasks-prepare_recipe_sysroot`
2436 task and when this task executes, it creates the ``recipe-sysroot``
2437 and ``recipe-sysroot-native`` in the recipe work directory (i.e.
2438 :term:`WORKDIR`). The OpenEmbedded build system
2439 creates hard links to copies of the relevant files from
2440 ``sysroots-components`` into the recipe work directory.
2441
2442 .. note::
2443
2444 If hard links are not possible, the build system uses actual
2445 copies.
2446
2447 The build system then addresses any "FIXMEs" to paths as defined from
2448 the list created in the first stage.
2449
2450 Finally, any files in ``${bindir}`` within the sysroot that have the
2451 prefix "``postinst-``" are executed.
2452
2453 .. note::
2454
2455 Although such sysroot post installation scripts are not
2456 recommended for general use, the files do allow some issues such
2457 as user creation and module indexes to be addressed.
2458
2459 Because recipes can have other dependencies outside of ``DEPENDS``
2460 (e.g. ``do_unpack[depends] += "tar-native:do_populate_sysroot"``),
2461 the sysroot creation function ``extend_recipe_sysroot`` is also added
2462 as a pre-function for those tasks whose dependencies are not through
2463 ``DEPENDS`` but operate similarly.
2464
2465 When installing dependencies into the sysroot, the code traverses the
2466 dependency graph and processes dependencies in exactly the same way
2467 as the dependencies would or would not be when installed from sstate.
2468 This processing means, for example, a native tool would have its
2469 native dependencies added but a target library would not have its
2470 dependencies traversed or installed. The same sstate dependency code
2471 is used so that builds should be identical regardless of whether
2472 sstate was used or not. For a closer look, see the
2473 ``setscene_depvalid()`` function in the
2474 :ref:`sstate <ref-classes-sstate>` class.
2475
2476 The build system is careful to maintain manifests of the files it
2477 installs so that any given dependency can be installed as needed. The
2478 sstate hash of the installed item is also stored so that if it
2479 changes, the build system can reinstall it.
2480
2481.. _ref-classes-syslinux:
2482
2483``syslinux.bbclass``
2484====================
2485
2486The ``syslinux`` class provides syslinux-specific functions for building
2487bootable images.
2488
2489The class supports the following variables:
2490
2491- :term:`INITRD`: Indicates list of filesystem images to
2492 concatenate and use as an initial RAM disk (initrd). This variable is
2493 optional.
2494
2495- :term:`ROOTFS`: Indicates a filesystem image to include
2496 as the root filesystem. This variable is optional.
2497
2498- :term:`AUTO_SYSLINUXMENU`: Enables creating
2499 an automatic menu when set to "1".
2500
2501- :term:`LABELS`: Lists targets for automatic
2502 configuration.
2503
2504- :term:`APPEND`: Lists append string overrides for each
2505 label.
2506
2507- :term:`SYSLINUX_OPTS`: Lists additional options
2508 to add to the syslinux file. Semicolon characters separate multiple
2509 options.
2510
2511- :term:`SYSLINUX_SPLASH`: Lists a background
2512 for the VGA boot menu when you are using the boot menu.
2513
2514- :term:`SYSLINUX_DEFAULT_CONSOLE`: Set
2515 to "console=ttyX" to change kernel boot default console.
2516
2517- :term:`SYSLINUX_SERIAL`: Sets an alternate
2518 serial port. Or, turns off serial when the variable is set with an
2519 empty string.
2520
2521- :term:`SYSLINUX_SERIAL_TTY`: Sets an
2522 alternate "console=tty..." kernel boot argument.
2523
2524.. _ref-classes-systemd:
2525
2526``systemd.bbclass``
2527===================
2528
2529The ``systemd`` class provides support for recipes that install systemd
2530unit files.
2531
2532The functionality for this class is disabled unless you have "systemd"
2533in :term:`DISTRO_FEATURES`.
2534
2535Under this class, the recipe or Makefile (i.e. whatever the recipe is
2536calling during the :ref:`ref-tasks-install` task)
2537installs unit files into
2538``${``\ :term:`D`\ ``}${systemd_unitdir}/system``. If the unit
2539files being installed go into packages other than the main package, you
2540need to set :term:`SYSTEMD_PACKAGES` in your
2541recipe to identify the packages in which the files will be installed.
2542
2543You should set :term:`SYSTEMD_SERVICE` to the
2544name of the service file. You should also use a package name override to
2545indicate the package to which the value applies. If the value applies to
2546the recipe's main package, use ``${``\ :term:`PN`\ ``}``. Here
2547is an example from the connman recipe:
2548::
2549
2550 SYSTEMD_SERVICE_${PN} = "connman.service"
2551
2552Services are set up to start on boot automatically
2553unless you have set
2554:term:`SYSTEMD_AUTO_ENABLE` to "disable".
2555
2556For more information on ``systemd``, see the
2557":ref:`dev-manual/dev-manual-common-tasks:selecting an initialization manager`"
2558section in the Yocto Project Development Tasks Manual.
2559
2560.. _ref-classes-systemd-boot:
2561
2562``systemd-boot.bbclass``
2563========================
2564
2565The ``systemd-boot`` class provides functions specific to the
2566systemd-boot bootloader for building bootable images. This is an
2567internal class and is not intended to be used directly.
2568
2569.. note::
2570
Andrew Geissler4c19ea12020-10-27 13:52:24 -05002571 The ``systemd-boot`` class is a result from merging the ``gummiboot`` class
2572 used in previous Yocto Project releases with the ``systemd`` project.
Andrew Geisslerc9f78652020-09-18 14:11:35 -05002573
2574Set the :term:`EFI_PROVIDER` variable to
2575"systemd-boot" to use this class. Doing so creates a standalone EFI
2576bootloader that is not dependent on systemd.
2577
2578For information on more variables used and supported in this class, see
2579the :term:`SYSTEMD_BOOT_CFG`,
2580:term:`SYSTEMD_BOOT_ENTRIES`, and
2581:term:`SYSTEMD_BOOT_TIMEOUT` variables.
2582
2583You can also see the `Systemd-boot
2584documentation <http://www.freedesktop.org/wiki/Software/systemd/systemd-boot/>`__
2585for more information.
2586
2587.. _ref-classes-terminal:
2588
2589``terminal.bbclass``
2590====================
2591
2592The ``terminal`` class provides support for starting a terminal session.
2593The :term:`OE_TERMINAL` variable controls which
2594terminal emulator is used for the session.
2595
2596Other classes use the ``terminal`` class anywhere a separate terminal
2597session needs to be started. For example, the
2598:ref:`patch <ref-classes-patch>` class assuming
2599:term:`PATCHRESOLVE` is set to "user", the
2600:ref:`cml1 <ref-classes-cml1>` class, and the
2601:ref:`devshell <ref-classes-devshell>` class all use the ``terminal``
2602class.
2603
2604.. _ref-classes-testimage*:
2605
2606``testimage*.bbclass``
2607======================
2608
2609The ``testimage*`` classes support running automated tests against
2610images using QEMU and on actual hardware. The classes handle loading the
2611tests and starting the image. To use the classes, you need to perform
2612steps to set up the environment.
2613
2614.. note::
2615
Andrew Geissler4c19ea12020-10-27 13:52:24 -05002616 Best practices include using :term:`IMAGE_CLASSES` rather than
2617 :term:`INHERIT` to inherit the ``testimage`` class for automated image
2618 testing.
Andrew Geisslerc9f78652020-09-18 14:11:35 -05002619
2620The tests are commands that run on the target system over ``ssh``. Each
2621test is written in Python and makes use of the ``unittest`` module.
2622
2623The ``testimage.bbclass`` runs tests on an image when called using the
2624following:
2625::
2626
2627 $ bitbake -c testimage image
2628
2629The ``testimage-auto`` class
2630runs tests on an image after the image is constructed (i.e.
2631:term:`TESTIMAGE_AUTO` must be set to "1").
2632
2633For information on how to enable, run, and create new tests, see the
2634":ref:`dev-manual/dev-manual-common-tasks:performing automated runtime testing`"
2635section in the Yocto Project Development Tasks Manual.
2636
2637.. _ref-classes-testsdk:
2638
2639``testsdk.bbclass``
2640===================
2641
2642This class supports running automated tests against software development
2643kits (SDKs). The ``testsdk`` class runs tests on an SDK when called
2644using the following:
2645::
2646
2647 $ bitbake -c testsdk image
2648
2649.. note::
2650
Andrew Geissler4c19ea12020-10-27 13:52:24 -05002651 Best practices include using :term:`IMAGE_CLASSES` rather than
2652 :term:`INHERIT` to inherit the ``testsdk`` class for automated SDK
2653 testing.
Andrew Geisslerc9f78652020-09-18 14:11:35 -05002654
2655.. _ref-classes-texinfo:
2656
2657``texinfo.bbclass``
2658===================
2659
2660This class should be inherited by recipes whose upstream packages invoke
2661the ``texinfo`` utilities at build-time. Native and cross recipes are
2662made to use the dummy scripts provided by ``texinfo-dummy-native``, for
2663improved performance. Target architecture recipes use the genuine
2664Texinfo utilities. By default, they use the Texinfo utilities on the
2665host system.
2666
2667.. note::
2668
2669 If you want to use the Texinfo recipe shipped with the build system,
Andrew Geissler4c19ea12020-10-27 13:52:24 -05002670 you can remove "texinfo-native" from :term:`ASSUME_PROVIDED` and makeinfo
2671 from :term:`SANITY_REQUIRED_UTILITIES`.
Andrew Geisslerc9f78652020-09-18 14:11:35 -05002672
2673.. _ref-classes-toaster:
2674
2675``toaster.bbclass``
2676===================
2677
2678The ``toaster`` class collects information about packages and images and
2679sends them as events that the BitBake user interface can receive. The
2680class is enabled when the Toaster user interface is running.
2681
2682This class is not intended to be used directly.
2683
2684.. _ref-classes-toolchain-scripts:
2685
2686``toolchain-scripts.bbclass``
2687=============================
2688
2689The ``toolchain-scripts`` class provides the scripts used for setting up
2690the environment for installed SDKs.
2691
2692.. _ref-classes-typecheck:
2693
2694``typecheck.bbclass``
2695=====================
2696
2697The ``typecheck`` class provides support for validating the values of
2698variables set at the configuration level against their defined types.
2699The OpenEmbedded build system allows you to define the type of a
2700variable using the "type" varflag. Here is an example:
2701::
2702
2703 IMAGE_FEATURES[type] = "list"
2704
2705.. _ref-classes-uboot-config:
2706
2707``uboot-config.bbclass``
2708========================
2709
2710The ``uboot-config`` class provides support for U-Boot configuration for
2711a machine. Specify the machine in your recipe as follows:
2712::
2713
2714 UBOOT_CONFIG ??= <default>
2715 UBOOT_CONFIG[foo] = "config,images"
2716
2717You can also specify the machine using this method:
2718::
2719
2720 UBOOT_MACHINE = "config"
2721
2722See the :term:`UBOOT_CONFIG` and :term:`UBOOT_MACHINE` variables for additional
2723information.
2724
2725.. _ref-classes-uninative:
2726
2727``uninative.bbclass``
2728=====================
2729
2730Attempts to isolate the build system from the host distribution's C
2731library in order to make re-use of native shared state artifacts across
2732different host distributions practical. With this class enabled, a
2733tarball containing a pre-built C library is downloaded at the start of
2734the build. In the Poky reference distribution this is enabled by default
2735through ``meta/conf/distro/include/yocto-uninative.inc``. Other
2736distributions that do not derive from poky can also
2737"``require conf/distro/include/yocto-uninative.inc``" to use this.
2738Alternatively if you prefer, you can build the uninative-tarball recipe
2739yourself, publish the resulting tarball (e.g. via HTTP) and set
2740``UNINATIVE_URL`` and ``UNINATIVE_CHECKSUM`` appropriately. For an
2741example, see the ``meta/conf/distro/include/yocto-uninative.inc``.
2742
2743The ``uninative`` class is also used unconditionally by the extensible
2744SDK. When building the extensible SDK, ``uninative-tarball`` is built
2745and the resulting tarball is included within the SDK.
2746
2747.. _ref-classes-update-alternatives:
2748
2749``update-alternatives.bbclass``
2750===============================
2751
2752The ``update-alternatives`` class helps the alternatives system when
2753multiple sources provide the same command. This situation occurs when
2754several programs that have the same or similar function are installed
2755with the same name. For example, the ``ar`` command is available from
2756the ``busybox``, ``binutils`` and ``elfutils`` packages. The
2757``update-alternatives`` class handles renaming the binaries so that
2758multiple packages can be installed without conflicts. The ``ar`` command
2759still works regardless of which packages are installed or subsequently
2760removed. The class renames the conflicting binary in each package and
2761symlinks the highest priority binary during installation or removal of
2762packages.
2763
2764To use this class, you need to define a number of variables:
2765
2766- :term:`ALTERNATIVE`
2767
2768- :term:`ALTERNATIVE_LINK_NAME`
2769
2770- :term:`ALTERNATIVE_TARGET`
2771
2772- :term:`ALTERNATIVE_PRIORITY`
2773
2774These variables list alternative commands needed by a package, provide
2775pathnames for links, default links for targets, and so forth. For
2776details on how to use this class, see the comments in the
2777:yocto_git:`update-alternatives.bbclass </cgit/cgit.cgi/poky/tree/meta/classes/update-alternatives.bbclass>`
2778file.
2779
2780.. note::
2781
Andrew Geissler4c19ea12020-10-27 13:52:24 -05002782 You can use the ``update-alternatives`` command directly in your recipes.
2783 However, this class simplifies things in most cases.
Andrew Geisslerc9f78652020-09-18 14:11:35 -05002784
2785.. _ref-classes-update-rc.d:
2786
2787``update-rc.d.bbclass``
2788=======================
2789
2790The ``update-rc.d`` class uses ``update-rc.d`` to safely install an
2791initialization script on behalf of the package. The OpenEmbedded build
2792system takes care of details such as making sure the script is stopped
2793before a package is removed and started when the package is installed.
2794
2795Three variables control this class: ``INITSCRIPT_PACKAGES``,
2796``INITSCRIPT_NAME`` and ``INITSCRIPT_PARAMS``. See the variable links
2797for details.
2798
2799.. _ref-classes-useradd:
2800
2801``useradd*.bbclass``
2802====================
2803
2804The ``useradd*`` classes support the addition of users or groups for
2805usage by the package on the target. For example, if you have packages
2806that contain system services that should be run under their own user or
2807group, you can use these classes to enable creation of the user or
2808group. The ``meta-skeleton/recipes-skeleton/useradd/useradd-example.bb``
2809recipe in the :term:`Source Directory` provides a simple
2810example that shows how to add three users and groups to two packages.
2811See the ``useradd-example.bb`` recipe for more information on how to use
2812these classes.
2813
2814The ``useradd_base`` class provides basic functionality for user or
2815groups settings.
2816
2817The ``useradd*`` classes support the
2818:term:`USERADD_PACKAGES`,
2819:term:`USERADD_PARAM`,
2820:term:`GROUPADD_PARAM`, and
2821:term:`GROUPMEMS_PARAM` variables.
2822
2823The ``useradd-staticids`` class supports the addition of users or groups
2824that have static user identification (``uid``) and group identification
2825(``gid``) values.
2826
2827The default behavior of the OpenEmbedded build system for assigning
2828``uid`` and ``gid`` values when packages add users and groups during
2829package install time is to add them dynamically. This works fine for
2830programs that do not care what the values of the resulting users and
2831groups become. In these cases, the order of the installation determines
2832the final ``uid`` and ``gid`` values. However, if non-deterministic
2833``uid`` and ``gid`` values are a problem, you can override the default,
2834dynamic application of these values by setting static values. When you
2835set static values, the OpenEmbedded build system looks in
2836:term:`BBPATH` for ``files/passwd`` and ``files/group``
2837files for the values.
2838
2839To use static ``uid`` and ``gid`` values, you need to set some
2840variables. See the :term:`USERADDEXTENSION`,
2841:term:`USERADD_UID_TABLES`,
2842:term:`USERADD_GID_TABLES`, and
2843:term:`USERADD_ERROR_DYNAMIC` variables.
2844You can also see the :ref:`useradd <ref-classes-useradd>` class for
2845additional information.
2846
2847.. note::
2848
Andrew Geissler4c19ea12020-10-27 13:52:24 -05002849 You do not use the ``useradd-staticids`` class directly. You either enable
2850 or disable the class by setting the ``USERADDEXTENSION`` variable. If you
2851 enable or disable the class in a configured system, :term:`TMPDIR` might
2852 contain incorrect ``uid`` and ``gid`` values. Deleting the ``TMPDIR``
Andrew Geisslerc9f78652020-09-18 14:11:35 -05002853 directory will correct this condition.
2854
2855.. _ref-classes-utility-tasks:
2856
2857``utility-tasks.bbclass``
2858=========================
2859
2860The ``utility-tasks`` class provides support for various "utility" type
2861tasks that are applicable to all recipes, such as
2862:ref:`ref-tasks-clean` and
2863:ref:`ref-tasks-listtasks`.
2864
2865This class is enabled by default because it is inherited by the
2866:ref:`base <ref-classes-base>` class.
2867
2868.. _ref-classes-utils:
2869
2870``utils.bbclass``
2871=================
2872
2873The ``utils`` class provides some useful Python functions that are
2874typically used in inline Python expressions (e.g. ``${@...}``). One
2875example use is for ``bb.utils.contains()``.
2876
2877This class is enabled by default because it is inherited by the
2878:ref:`base <ref-classes-base>` class.
2879
2880.. _ref-classes-vala:
2881
2882``vala.bbclass``
2883================
2884
2885The ``vala`` class supports recipes that need to build software written
2886using the Vala programming language.
2887
2888.. _ref-classes-waf:
2889
2890``waf.bbclass``
2891===============
2892
2893The ``waf`` class supports recipes that need to build software that uses
2894the Waf build system. You can use the
2895:term:`EXTRA_OECONF` or
2896:term:`PACKAGECONFIG_CONFARGS` variables
2897to specify additional configuration options to be passed on the Waf
2898command line.