1.. SPDX-License-Identifier: CC-BY-SA-2.0-UK
2
3******************
4Variables Glossary
5******************
6
7This chapter lists common variables used in the OpenEmbedded build
8system and gives an overview of their function and contents.
9
10:term:`A <ABIEXTENSION>` :term:`B` :term:`C <CACHE>`
11:term:`D` :term:`E <EFI_PROVIDER>` :term:`F <FEATURE_PACKAGES>`
12:term:`G <GCCPIE>` :term:`H <HOMEPAGE>` :term:`I <ICECC_DISABLED>`
13:term:`K <KARCH>` :term:`L <LABELS>` :term:`M <MACHINE>`
14:term:`N <NATIVELSBSTRING>` :term:`O <OBJCOPY>` :term:`P`
15:term:`R <RANLIB>` :term:`S` :term:`T`
16:term:`U <UBOOT_CONFIG>` :term:`V <VOLATILE_LOG_DIR>`
17:term:`W <WARN_QA>` :term:`X <XSERVER>`
18
19.. glossary::
20
21   :term:`ABIEXTENSION`
22      Extension to the Application Binary Interface (ABI) field of the GNU
23      canonical architecture name (e.g. "eabi").
24
25      ABI extensions are set in the machine include files. For example, the
26      ``meta/conf/machine/include/arm/arch-arm.inc`` file sets the
27      following extension::
28
29         ABIEXTENSION = "eabi"
30
31   :term:`ALLOW_EMPTY`
32      Specifies whether to produce an output package even if it is empty.
33      By default, BitBake does not produce empty packages. This default
34      behavior can cause issues when there is an
35      :term:`RDEPENDS` or some other hard runtime
36      requirement on the existence of the package.
37
38      Like all package-controlling variables, you must always use them in
39      conjunction with a package name override, as in::
40
41         ALLOW_EMPTY:${PN} = "1"
42         ALLOW_EMPTY:${PN}-dev = "1"
43         ALLOW_EMPTY:${PN}-staticdev = "1"
44
45   :term:`ALTERNATIVE`
46      Lists commands in a package that need an alternative binary naming
47      scheme. Sometimes the same command is provided in multiple packages.
48      When this occurs, the OpenEmbedded build system needs to use the
49      alternatives system to create a different binary naming scheme so the
50      commands can co-exist.
51
52      To use the variable, list out the package's commands that are also
53      provided by another package. For example, if the ``busybox`` package
54      has four such commands, you identify them as follows::
55
56         ALTERNATIVE:busybox = "sh sed test bracket"
57
58      For more information on the alternatives system, see the
59      ":ref:`update-alternatives.bbclass <ref-classes-update-alternatives>`"
60      section.
61
62   :term:`ALTERNATIVE_LINK_NAME`
63      Used by the alternatives system to map duplicated commands to actual
64      locations. For example, if the ``bracket`` command provided by the
65      ``busybox`` package is duplicated through another package, you must
66      use the :term:`ALTERNATIVE_LINK_NAME` variable to specify the actual
67      location::
68
69         ALTERNATIVE_LINK_NAME[bracket] = "/usr/bin/["
70
71      In this example, the binary for the ``bracket`` command (i.e. ``[``)
72      from the ``busybox`` package resides in ``/usr/bin/``.
73
74      .. note::
75
76         If :term:`ALTERNATIVE_LINK_NAME` is not defined, it defaults to ``${bindir}/name``.
77
78      For more information on the alternatives system, see the
79      ":ref:`update-alternatives.bbclass <ref-classes-update-alternatives>`"
80      section.
81
82   :term:`ALTERNATIVE_PRIORITY`
83      Used by the alternatives system to create default priorities for
84      duplicated commands. You can use the variable to create a single
85      default regardless of the command name or package, a default for
86      specific duplicated commands regardless of the package, or a default
87      for specific commands tied to particular packages. Here are the
88      available syntax forms::
89
90         ALTERNATIVE_PRIORITY = "priority"
91         ALTERNATIVE_PRIORITY[name] = "priority"
92         ALTERNATIVE_PRIORITY_pkg[name] = "priority"
93
94      For more information on the alternatives system, see the
95      ":ref:`update-alternatives.bbclass <ref-classes-update-alternatives>`"
96      section.
97
98   :term:`ALTERNATIVE_TARGET`
99      Used by the alternatives system to create default link locations for
100      duplicated commands. You can use the variable to create a single
101      default location for all duplicated commands regardless of the
102      command name or package, a default for specific duplicated commands
103      regardless of the package, or a default for specific commands tied to
104      particular packages. Here are the available syntax forms::
105
106         ALTERNATIVE_TARGET = "target"
107         ALTERNATIVE_TARGET[name] = "target"
108         ALTERNATIVE_TARGET_pkg[name] = "target"
109
110      .. note::
111
112         If :term:`ALTERNATIVE_TARGET` is not defined, it inherits the value
113         from the :term:`ALTERNATIVE_LINK_NAME` variable.
114
115         If :term:`ALTERNATIVE_LINK_NAME` and :term:`ALTERNATIVE_TARGET` are the
116         same, the target for :term:`ALTERNATIVE_TARGET` has "``.{BPN}``"
117         appended to it.
118
119         Finally, if the file referenced has not been renamed, the
120         alternatives system will rename it to avoid the need to rename
121         alternative files in the :ref:`ref-tasks-install`
122         task while retaining support for the command if necessary.
123
124      For more information on the alternatives system, see the
125      ":ref:`update-alternatives.bbclass <ref-classes-update-alternatives>`"
126      section.
127
128   :term:`ANY_OF_DISTRO_FEATURES`
129      When inheriting the
130      :ref:`features_check <ref-classes-features_check>`
131      class, this variable identifies a list of distribution features where
132      at least one must be enabled in the current configuration in order
133      for the OpenEmbedded build system to build the recipe. In other words,
134      if none of the features listed in :term:`ANY_OF_DISTRO_FEATURES`
135      appear in :term:`DISTRO_FEATURES` within the current configuration, then
136      the recipe will be skipped, and if the build system attempts to build
137      the recipe then an error will be triggered.
138
139
140   :term:`APPEND`
141      An override list of append strings for each target specified with
142      :term:`LABELS`.
143
144      See the :ref:`grub-efi <ref-classes-grub-efi>` class for more
145      information on how this variable is used.
146
147   :term:`AR`
148      The minimal command and arguments used to run ``ar``.
149
150   :term:`ARCHIVER_MODE`
151      When used with the :ref:`archiver <ref-classes-archiver>` class,
152      determines the type of information used to create a released archive.
153      You can use this variable to create archives of patched source,
154      original source, configured source, and so forth by employing the
155      following variable flags (varflags)::
156
157         ARCHIVER_MODE[src] = "original"                   # Uses original (unpacked) source files.
158         ARCHIVER_MODE[src] = "patched"                    # Uses patched source files. This is the default.
159         ARCHIVER_MODE[src] = "configured"                 # Uses configured source files.
160         ARCHIVER_MODE[diff] = "1"                         # Uses patches between do_unpack and do_patch.
161         ARCHIVER_MODE[diff-exclude] ?= "file file ..."    # Lists files and directories to exclude from diff.
162         ARCHIVER_MODE[dumpdata] = "1"                     # Uses environment data.
163         ARCHIVER_MODE[recipe] = "1"                       # Uses recipe and include files.
164         ARCHIVER_MODE[srpm] = "1"                         # Uses RPM package files.
165
166      For information on how the variable works, see the
167      ``meta/classes/archiver.bbclass`` file in the :term:`Source Directory`.
168
169   :term:`AS`
170      Minimal command and arguments needed to run the assembler.
171
172   :term:`ASSUME_PROVIDED`
173      Lists recipe names (:term:`PN` values) BitBake does not
174      attempt to build. Instead, BitBake assumes these recipes have already
175      been built.
176
177      In OpenEmbedded-Core, :term:`ASSUME_PROVIDED` mostly specifies native
178      tools that should not be built. An example is ``git-native``, which
179      when specified, allows for the Git binary from the host to be used
180      rather than building ``git-native``.
181
182   :term:`ASSUME_SHLIBS`
183      Provides additional ``shlibs`` provider mapping information, which
184      adds to or overwrites the information provided automatically by the
185      system. Separate multiple entries using spaces.
186
187      As an example, use the following form to add an ``shlib`` provider of
188      shlibname in packagename with the optional version::
189
190         shlibname:packagename[_version]
191
192      Here is an example that adds a shared library named ``libEGL.so.1``
193      as being provided by the ``libegl-implementation`` package::
194
195         ASSUME_SHLIBS = "libEGL.so.1:libegl-implementation"
196
197   :term:`AUTHOR`
198      The email address used to contact the original author or authors in
199      order to send patches and forward bugs.
200
201   :term:`AUTO_LIBNAME_PKGS`
202      When the :ref:`debian <ref-classes-debian>` class is inherited,
203      which is the default behavior, :term:`AUTO_LIBNAME_PKGS` specifies which
204      packages should be checked for libraries and renamed according to
205      Debian library package naming.
206
207      The default value is "${PACKAGES}", which causes the debian class to
208      act on all packages that are explicitly generated by the recipe.
209
210   :term:`AUTO_SYSLINUXMENU`
211      Enables creating an automatic menu for the syslinux bootloader. You
212      must set this variable in your recipe. The
213      :ref:`syslinux <ref-classes-syslinux>` class checks this variable.
214
215   :term:`AUTOREV`
216      When :term:`SRCREV` is set to the value of this variable, it specifies to
217      use the latest source revision in the repository. Here is an example::
218
219         SRCREV = "${AUTOREV}"
220
221      If you use the previous statement to retrieve the latest version of
222      software, you need to be sure :term:`PV` contains
223      ``${``\ :term:`SRCPV`\ ``}``. For example, suppose you
224      have a kernel recipe that inherits the
225      :ref:`kernel <ref-classes-kernel>` class and you use the previous
226      statement. In this example, ``${SRCPV}`` does not automatically get
227      into :term:`PV`. Consequently, you need to change :term:`PV` in your recipe
228      so that it does contain ``${SRCPV}``.
229
230      For more information see the
231      ":ref:`dev-manual/common-tasks:automatically incrementing a package version number`"
232      section in the Yocto Project Development Tasks Manual.
233
234   :term:`AVAILABLE_LICENSES`
235      List of licenses found in the directories specified by
236      :term:`COMMON_LICENSE_DIR` and
237      :term:`LICENSE_PATH`.
238
239      .. note::
240
241         It is assumed that all changes to :term:`COMMON_LICENSE_DIR` and
242         :term:`LICENSE_PATH` have been done before :term:`AVAILABLE_LICENSES`
243         is defined (in :ref:`ref-classes-license`).
244
245   :term:`AVAILTUNES`
246      The list of defined CPU and Application Binary Interface (ABI)
247      tunings (i.e. "tunes") available for use by the OpenEmbedded build
248      system.
249
250      The list simply presents the tunes that are available. Not all tunes
251      may be compatible with a particular machine configuration, or with
252      each other in a
253      :ref:`Multilib <dev-manual/common-tasks:combining multiple versions of library files into one image>`
254      configuration.
255
256      To add a tune to the list, be sure to append it with spaces using the
257      "+=" BitBake operator. Do not simply replace the list by using the
258      "=" operator. See the
259      ":ref:`bitbake:bitbake-user-manual/bitbake-user-manual-metadata:basic syntax`" section in the BitBake
260      User Manual for more information.
261
262   :term:`AZ_SAS`
263      Azure Storage Shared Access Signature, when using the
264      :ref:`Azure Storage fetcher (az://) <bitbake:bitbake-user-manual/bitbake-user-manual-fetching:fetchers>`
265      This variable can be defined to be used by the fetcher to authenticate
266      and gain access to non-public artifacts.
267      ::
268
269         AZ_SAS = ""se=2021-01-01&sp=r&sv=2018-11-09&sr=c&skoid=<skoid>&sig=<signature>""
270
271      For more information see Microsoft's Azure Storage documentation at
272      https://docs.microsoft.com/en-us/azure/storage/common/storage-sas-overview
273
274   :term:`B`
275      The directory within the :term:`Build Directory` in
276      which the OpenEmbedded build system places generated objects during a
277      recipe's build process. By default, this directory is the same as the
278      :term:`S` directory, which is defined as::
279
280         S = "${WORKDIR}/${BP}"
281
282      You can separate the (:term:`S`) directory and the directory pointed to
283      by the :term:`B` variable. Most Autotools-based recipes support
284      separating these directories. The build system defaults to using
285      separate directories for ``gcc`` and some kernel recipes.
286
287   :term:`BAD_RECOMMENDATIONS`
288      Lists "recommended-only" packages to not install. Recommended-only
289      packages are packages installed only through the
290      :term:`RRECOMMENDS` variable. You can prevent any
291      of these "recommended" packages from being installed by listing them
292      with the :term:`BAD_RECOMMENDATIONS` variable::
293
294         BAD_RECOMMENDATIONS = "package_name package_name package_name ..."
295
296      You can set this variable globally in your ``local.conf`` file or you
297      can attach it to a specific image recipe by using the recipe name
298      override::
299
300         BAD_RECOMMENDATIONS:pn-target_image = "package_name"
301
302      It is important to realize that if you choose to not install packages
303      using this variable and some other packages are dependent on them
304      (i.e. listed in a recipe's :term:`RDEPENDS`
305      variable), the OpenEmbedded build system ignores your request and
306      will install the packages to avoid dependency errors.
307
308      This variable is supported only when using the IPK and RPM
309      packaging backends. DEB is not supported.
310
311      See the :term:`NO_RECOMMENDATIONS` and the
312      :term:`PACKAGE_EXCLUDE` variables for related
313      information.
314
315   :term:`BASE_LIB`
316      The library directory name for the CPU or Application Binary
317      Interface (ABI) tune. The :term:`BASE_LIB` applies only in the Multilib
318      context. See the ":ref:`dev-manual/common-tasks:combining multiple versions of library files into one image`"
319      section in the Yocto Project Development Tasks Manual for information
320      on Multilib.
321
322      The :term:`BASE_LIB` variable is defined in the machine include files in
323      the :term:`Source Directory`. If Multilib is not
324      being used, the value defaults to "lib".
325
326   :term:`BASE_WORKDIR`
327      Points to the base of the work directory for all recipes. The default
328      value is "${TMPDIR}/work".
329
330   :term:`BB_ALLOWED_NETWORKS`
331      Specifies a space-delimited list of hosts that the fetcher is allowed
332      to use to obtain the required source code. Following are
333      considerations surrounding this variable:
334
335      -  This host list is only used if :term:`BB_NO_NETWORK` is either not set
336         or set to "0".
337
338      -  There is limited support for wildcard matching against the beginning of
339         host names. For example, the following setting matches
340         ``git.gnu.org``, ``ftp.gnu.org``, and ``foo.git.gnu.org``.
341         ::
342
343            BB_ALLOWED_NETWORKS = "*.gnu.org"
344
345         .. note::
346
347            The use of the "``*``" character only works at the beginning of
348            a host name and it must be isolated from the remainder of the
349            host name. You cannot use the wildcard character in any other
350            location of the name or combined with the front part of the
351            name.
352
353            For example, ``*.foo.bar`` is supported, while ``*aa.foo.bar``
354            is not.
355
356      -  Mirrors not in the host list are skipped and logged in debug.
357
358      -  Attempts to access networks not in the host list cause a failure.
359
360      Using :term:`BB_ALLOWED_NETWORKS` in conjunction with
361      :term:`PREMIRRORS` is very useful. Adding the host
362      you want to use to :term:`PREMIRRORS` results in the source code being
363      fetched from an allowed location and avoids raising an error when a
364      host that is not allowed is in a :term:`SRC_URI`
365      statement. This is because the fetcher does not attempt to use the
366      host listed in :term:`SRC_URI` after a successful fetch from the
367      :term:`PREMIRRORS` occurs.
368
369   :term:`BB_DANGLINGAPPENDS_WARNONLY`
370      Defines how BitBake handles situations where an append file
371      (``.bbappend``) has no corresponding recipe file (``.bb``). This
372      condition often occurs when layers get out of sync (e.g. ``oe-core``
373      bumps a recipe version and the old recipe no longer exists and the
374      other layer has not been updated to the new version of the recipe
375      yet).
376
377      The default fatal behavior is safest because it is the sane reaction
378      given something is out of sync. It is important to realize when your
379      changes are no longer being applied.
380
381      You can change the default behavior by setting this variable to "1",
382      "yes", or "true" in your ``local.conf`` file, which is located in the
383      :term:`Build Directory`: Here is an example::
384
385         BB_DANGLINGAPPENDS_WARNONLY = "1"
386
387   :term:`BB_DISKMON_DIRS`
388      Monitors disk space and available inodes during the build and allows
389      you to control the build based on these parameters.
390
391      Disk space monitoring is disabled by default. To enable monitoring,
392      add the :term:`BB_DISKMON_DIRS` variable to your ``conf/local.conf`` file
393      found in the :term:`Build Directory`. Use the
394      following form:
395
396      .. code-block:: none
397
398         BB_DISKMON_DIRS = "action,dir,threshold [...]"
399
400         where:
401
402            action is:
403               ABORT:     Immediately abort the build when
404                          a threshold is broken.
405               STOPTASKS: Stop the build after the currently
406                          executing tasks have finished when
407                          a threshold is broken.
408               WARN:      Issue a warning but continue the
409                          build when a threshold is broken.
410                          Subsequent warnings are issued as
411                          defined by the BB_DISKMON_WARNINTERVAL
412                          variable, which must be defined in
413                          the conf/local.conf file.
414
415            dir is:
416               Any directory you choose. You can specify one or
417               more directories to monitor by separating the
418               groupings with a space.  If two directories are
419               on the same device, only the first directory
420               is monitored.
421
422            threshold is:
423               Either the minimum available disk space,
424               the minimum number of free inodes, or
425               both.  You must specify at least one.  To
426               omit one or the other, simply omit the value.
427               Specify the threshold using G, M, K for Gbytes,
428               Mbytes, and Kbytes, respectively. If you do
429               not specify G, M, or K, Kbytes is assumed by
430               default.  Do not use GB, MB, or KB.
431
432      Here are some examples::
433
434         BB_DISKMON_DIRS = "ABORT,${TMPDIR},1G,100K WARN,${SSTATE_DIR},1G,100K"
435         BB_DISKMON_DIRS = "STOPTASKS,${TMPDIR},1G"
436         BB_DISKMON_DIRS = "ABORT,${TMPDIR},,100K"
437
438      The first example works only if you also provide the
439      :term:`BB_DISKMON_WARNINTERVAL`
440      variable in the ``conf/local.conf``. This example causes the build
441      system to immediately abort when either the disk space in
442      ``${TMPDIR}`` drops below 1 Gbyte or the available free inodes drops
443      below 100 Kbytes. Because two directories are provided with the
444      variable, the build system also issue a warning when the disk space
445      in the ``${SSTATE_DIR}`` directory drops below 1 Gbyte or the number
446      of free inodes drops below 100 Kbytes. Subsequent warnings are issued
447      during intervals as defined by the :term:`BB_DISKMON_WARNINTERVAL`
448      variable.
449
450      The second example stops the build after all currently executing
451      tasks complete when the minimum disk space in the ``${TMPDIR}``
452      directory drops below 1 Gbyte. No disk monitoring occurs for the free
453      inodes in this case.
454
455      The final example immediately aborts the build when the number of
456      free inodes in the ``${TMPDIR}`` directory drops below 100 Kbytes. No
457      disk space monitoring for the directory itself occurs in this case.
458
459   :term:`BB_DISKMON_WARNINTERVAL`
460      Defines the disk space and free inode warning intervals. To set these
461      intervals, define the variable in your ``conf/local.conf`` file in
462      the :term:`Build Directory`.
463
464      If you are going to use the :term:`BB_DISKMON_WARNINTERVAL` variable, you
465      must also use the :term:`BB_DISKMON_DIRS`
466      variable and define its action as "WARN". During the build,
467      subsequent warnings are issued each time disk space or number of free
468      inodes further reduces by the respective interval.
469
470      If you do not provide a :term:`BB_DISKMON_WARNINTERVAL` variable and you
471      do use :term:`BB_DISKMON_DIRS` with the "WARN" action, the disk
472      monitoring interval defaults to the following::
473
474         BB_DISKMON_WARNINTERVAL = "50M,5K"
475
476      When specifying the variable in your configuration file, use the
477      following form:
478
479      .. code-block:: none
480
481         BB_DISKMON_WARNINTERVAL = "disk_space_interval,disk_inode_interval"
482
483         where:
484
485            disk_space_interval is:
486               An interval of memory expressed in either
487               G, M, or K for Gbytes, Mbytes, or Kbytes,
488               respectively. You cannot use GB, MB, or KB.
489
490            disk_inode_interval is:
491               An interval of free inodes expressed in either
492               G, M, or K for Gbytes, Mbytes, or Kbytes,
493               respectively. You cannot use GB, MB, or KB.
494
495      Here is an example::
496
497         BB_DISKMON_DIRS = "WARN,${SSTATE_DIR},1G,100K"
498         BB_DISKMON_WARNINTERVAL = "50M,5K"
499
500      These variables cause the
501      OpenEmbedded build system to issue subsequent warnings each time the
502      available disk space further reduces by 50 Mbytes or the number of
503      free inodes further reduces by 5 Kbytes in the ``${SSTATE_DIR}``
504      directory. Subsequent warnings based on the interval occur each time
505      a respective interval is reached beyond the initial warning (i.e. 1
506      Gbytes and 100 Kbytes).
507
508   :term:`BB_GENERATE_MIRROR_TARBALLS`
509      Causes tarballs of the source control repositories (e.g. Git
510      repositories), including metadata, to be placed in the
511      :term:`DL_DIR` directory.
512
513      For performance reasons, creating and placing tarballs of these
514      repositories is not the default action by the OpenEmbedded build
515      system.
516      ::
517
518         BB_GENERATE_MIRROR_TARBALLS = "1"
519
520      Set this variable in your
521      ``local.conf`` file in the :term:`Build Directory`.
522
523      Once you have the tarballs containing your source files, you can
524      clean up your :term:`DL_DIR` directory by deleting any Git or other
525      source control work directories.
526
527   :term:`BB_NUMBER_THREADS`
528      The maximum number of tasks BitBake should run in parallel at any one
529      time. The OpenEmbedded build system automatically configures this
530      variable to be equal to the number of cores on the build system. For
531      example, a system with a dual core processor that also uses
532      hyper-threading causes the :term:`BB_NUMBER_THREADS` variable to default
533      to "4".
534
535      For single socket systems (i.e. one CPU), you should not have to
536      override this variable to gain optimal parallelism during builds.
537      However, if you have very large systems that employ multiple physical
538      CPUs, you might want to make sure the :term:`BB_NUMBER_THREADS` variable
539      is not set higher than "20".
540
541      For more information on speeding up builds, see the
542      ":ref:`dev-manual/common-tasks:speeding up a build`"
543      section in the Yocto Project Development Tasks Manual.
544
545   :term:`BB_SERVER_TIMEOUT`
546      Specifies the time (in seconds) after which to unload the BitBake
547      server due to inactivity. Set :term:`BB_SERVER_TIMEOUT` to determine how
548      long the BitBake server stays resident between invocations.
549
550      For example, the following statement in your ``local.conf`` file
551      instructs the server to be unloaded after 20 seconds of inactivity::
552
553         BB_SERVER_TIMEOUT = "20"
554
555      If you want the server to never be unloaded,
556      set :term:`BB_SERVER_TIMEOUT` to "-1".
557
558   :term:`BBCLASSEXTEND`
559      Allows you to extend a recipe so that it builds variants of the
560      software. There are common variants for recipes as "natives" like
561      ``quilt-native``, which is a copy of Quilt built to run on the build
562      system; "crosses" such as ``gcc-cross``, which is a compiler built to
563      run on the build machine but produces binaries that run on the target
564      :term:`MACHINE`; "nativesdk", which targets the SDK
565      machine instead of :term:`MACHINE`; and "mulitlibs" in the form
566      "``multilib:``\ multilib_name".
567
568      To build a different variant of the recipe with a minimal amount of
569      code, it usually is as simple as adding the following to your recipe::
570
571         BBCLASSEXTEND =+ "native nativesdk"
572         BBCLASSEXTEND =+ "multilib:multilib_name"
573
574      .. note::
575
576         Internally, the :term:`BBCLASSEXTEND` mechanism generates recipe
577         variants by rewriting variable values and applying overrides such
578         as ``:class-native``. For example, to generate a native version of
579         a recipe, a :term:`DEPENDS` on "foo" is rewritten
580         to a :term:`DEPENDS` on "foo-native".
581
582         Even when using :term:`BBCLASSEXTEND`, the recipe is only parsed once.
583         Parsing once adds some limitations. For example, it is not
584         possible to include a different file depending on the variant,
585         since ``include`` statements are processed when the recipe is
586         parsed.
587
588   :term:`BBFILE_COLLECTIONS`
589      Lists the names of configured layers. These names are used to find
590      the other ``BBFILE_*`` variables. Typically, each layer will append
591      its name to this variable in its ``conf/layer.conf`` file.
592
593   :term:`BBFILE_PATTERN`
594      Variable that expands to match files from
595      :term:`BBFILES` in a particular layer. This variable
596      is used in the ``conf/layer.conf`` file and must be suffixed with the
597      name of the specific layer (e.g. ``BBFILE_PATTERN_emenlow``).
598
599   :term:`BBFILE_PRIORITY`
600      Assigns the priority for recipe files in each layer.
601
602      This variable is useful in situations where the same recipe appears
603      in more than one layer. Setting this variable allows you to
604      prioritize a layer against other layers that contain the same recipe
605      - effectively letting you control the precedence for the multiple
606      layers. The precedence established through this variable stands
607      regardless of a recipe's version (:term:`PV` variable). For
608      example, a layer that has a recipe with a higher :term:`PV` value but for
609      which the :term:`BBFILE_PRIORITY` is set to have a lower precedence still
610      has a lower precedence.
611
612      A larger value for the :term:`BBFILE_PRIORITY` variable results in a
613      higher precedence. For example, the value 6 has a higher precedence
614      than the value 5. If not specified, the :term:`BBFILE_PRIORITY` variable
615      is set based on layer dependencies (see the :term:`LAYERDEPENDS` variable
616      for more information. The default priority, if unspecified for a
617      layer with no dependencies, is the lowest defined priority + 1 (or 1
618      if no priorities are defined).
619
620      .. tip::
621
622         You can use the command ``bitbake-layers show-layers``
623         to list all configured layers along with their priorities.
624
625   :term:`BBFILES`
626      A space-separated list of recipe files BitBake uses to build
627      software.
628
629      When specifying recipe files, you can pattern match using Python's
630      `glob <https://docs.python.org/3/library/glob.html>`_ syntax.
631      For details on the syntax, see the documentation by following the
632      previous link.
633
634   :term:`BBFILES_DYNAMIC`
635      Activates content when identified layers are present. You identify
636      the layers by the collections that the layers define.
637
638      Use the :term:`BBFILES_DYNAMIC` variable to avoid ``.bbappend`` files
639      whose corresponding ``.bb`` file is in a layer that attempts to
640      modify other layers through ``.bbappend`` but does not want to
641      introduce a hard dependency on those other layers.
642
643      Use the following form for :term:`BBFILES_DYNAMIC`:
644      collection_name:filename_pattern The following example identifies two
645      collection names and two filename patterns::
646
647         BBFILES_DYNAMIC += " \
648            clang-layer:${LAYERDIR}/bbappends/meta-clang/*/*/*.bbappend \
649            core:${LAYERDIR}/bbappends/openembedded-core/meta/*/*/*.bbappend \
650            "
651
652      This next example shows an error message that occurs because invalid
653      entries are found, which cause parsing to abort:
654
655      .. code-block:: none
656
657         ERROR: BBFILES_DYNAMIC entries must be of the form <collection name>:<filename pattern>, not:
658             /work/my-layer/bbappends/meta-security-isafw/*/*/*.bbappend
659             /work/my-layer/bbappends/openembedded-core/meta/*/*/*.bbappend
660
661   :term:`BBINCLUDELOGS`
662      Variable that controls how BitBake displays logs on build failure.
663
664   :term:`BBINCLUDELOGS_LINES`
665      If :term:`BBINCLUDELOGS` is set, specifies the
666      maximum number of lines from the task log file to print when
667      reporting a failed task. If you do not set :term:`BBINCLUDELOGS_LINES`,
668      the entire log is printed.
669
670   :term:`BBLAYERS`
671      Lists the layers to enable during the build. This variable is defined
672      in the ``bblayers.conf`` configuration file in the :term:`Build Directory`.
673      Here is an example::
674
675         BBLAYERS = " \
676             /home/scottrif/poky/meta \
677             /home/scottrif/poky/meta-poky \
678             /home/scottrif/poky/meta-yocto-bsp \
679             /home/scottrif/poky/meta-mykernel \
680             "
681
682      This example enables four layers, one of which is a custom,
683      user-defined layer named ``meta-mykernel``.
684
685   :term:`BBMASK`
686      Prevents BitBake from processing recipes and recipe append files.
687
688      You can use the :term:`BBMASK` variable to "hide" these ``.bb`` and
689      ``.bbappend`` files. BitBake ignores any recipe or recipe append
690      files that match any of the expressions. It is as if BitBake does not
691      see them at all. Consequently, matching files are not parsed or
692      otherwise used by BitBake.
693
694      The values you provide are passed to Python's regular expression
695      compiler. Consequently, the syntax follows Python's Regular
696      Expression (re) syntax. The expressions are compared against the full
697      paths to the files. For complete syntax information, see Python's
698      documentation at https://docs.python.org/3/library/re.html#regular-expression-syntax.
699
700      The following example uses a complete regular expression to tell
701      BitBake to ignore all recipe and recipe append files in the
702      ``meta-ti/recipes-misc/`` directory::
703
704         BBMASK = "meta-ti/recipes-misc/"
705
706      If you want to mask out multiple directories or recipes, you can
707      specify multiple regular expression fragments. This next example
708      masks out multiple directories and individual recipes::
709
710         BBMASK += "/meta-ti/recipes-misc/ meta-ti/recipes-ti/packagegroup/"
711         BBMASK += "/meta-oe/recipes-support/"
712         BBMASK += "/meta-foo/.*/openldap"
713         BBMASK += "opencv.*\.bbappend"
714         BBMASK += "lzma"
715
716      .. note::
717
718         When specifying a directory name, use the trailing slash character
719         to ensure you match just that directory name.
720
721   :term:`BBMULTICONFIG`
722      Specifies each additional separate configuration when you are
723      building targets with multiple configurations. Use this variable in
724      your ``conf/local.conf`` configuration file. Specify a
725      multiconfigname for each configuration file you are using. For
726      example, the following line specifies three configuration files::
727
728         BBMULTICONFIG = "configA configB configC"
729
730      Each configuration file you
731      use must reside in the :term:`Build Directory`
732      ``conf/multiconfig`` directory (e.g.
733      build_directory\ ``/conf/multiconfig/configA.conf``).
734
735      For information on how to use :term:`BBMULTICONFIG` in an environment
736      that supports building targets with multiple configurations, see the
737      ":ref:`dev-manual/common-tasks:building images for multiple targets using multiple configurations`"
738      section in the Yocto Project Development Tasks Manual.
739
740   :term:`BBPATH`
741      Used by BitBake to locate ``.bbclass`` and configuration files. This
742      variable is analogous to the ``PATH`` variable.
743
744      .. note::
745
746         If you run BitBake from a directory outside of the
747         :term:`Build Directory`, you must be sure to set :term:`BBPATH`
748         to point to the Build Directory. Set the variable as you would any
749         environment variable and then run BitBake::
750
751                 $ BBPATH = "build_directory"
752                 $ export BBPATH
753                 $ bitbake target
754
755
756   :term:`BBSERVER`
757      If defined in the BitBake environment, :term:`BBSERVER` points to the
758      BitBake remote server.
759
760      Use the following format to export the variable to the BitBake
761      environment::
762
763         export BBSERVER=localhost:$port
764
765      By default, :term:`BBSERVER` also appears in :term:`BB_HASHBASE_WHITELIST`.
766      Consequently, :term:`BBSERVER` is excluded from checksum and dependency
767      data.
768
769   :term:`BINCONFIG`
770      When inheriting the
771      :ref:`binconfig-disabled <ref-classes-binconfig-disabled>` class,
772      this variable specifies binary configuration scripts to disable in
773      favor of using ``pkg-config`` to query the information. The
774      ``binconfig-disabled`` class will modify the specified scripts to
775      return an error so that calls to them can be easily found and
776      replaced.
777
778      To add multiple scripts, separate them by spaces. Here is an example
779      from the ``libpng`` recipe::
780
781         BINCONFIG = "${bindir}/libpng-config ${bindir}/libpng16-config"
782
783   :term:`BINCONFIG_GLOB`
784      When inheriting the :ref:`binconfig <ref-classes-binconfig>` class,
785      this variable specifies a wildcard for configuration scripts that
786      need editing. The scripts are edited to correct any paths that have
787      been set up during compilation so that they are correct for use when
788      installed into the sysroot and called by the build processes of other
789      recipes.
790
791      .. note::
792
793         The :term:`BINCONFIG_GLOB` variable uses
794         `shell globbing <https://tldp.org/LDP/abs/html/globbingref.html>`__,
795         which is recognition and expansion of wildcards during pattern
796         matching. Shell globbing is very similar to
797         `fnmatch <https://docs.python.org/3/library/fnmatch.html#module-fnmatch>`__
798         and `glob <https://docs.python.org/3/library/glob.html>`__.
799
800      For more information on how this variable works, see
801      ``meta/classes/binconfig.bbclass`` in the :term:`Source Directory`.
802      You can also find general
803      information on the class in the
804      ":ref:`binconfig.bbclass <ref-classes-binconfig>`" section.
805
806   :term:`BP`
807      The base recipe name and version but without any special recipe name
808      suffix (i.e. ``-native``, ``lib64-``, and so forth). :term:`BP` is
809      comprised of the following::
810
811         ${BPN}-${PV}
812
813   :term:`BPN`
814      This variable is a version of the :term:`PN` variable with
815      common prefixes and suffixes removed, such as ``nativesdk-``,
816      ``-cross``, ``-native``, and multilib's ``lib64-`` and ``lib32-``.
817      The exact lists of prefixes and suffixes removed are specified by the
818      :term:`MLPREFIX` and
819      :term:`SPECIAL_PKGSUFFIX` variables,
820      respectively.
821
822   :term:`BUGTRACKER`
823      Specifies a URL for an upstream bug tracking website for a recipe.
824      The OpenEmbedded build system does not use this variable. Rather, the
825      variable is a useful pointer in case a bug in the software being
826      built needs to be manually reported.
827
828   :term:`BUILD_ARCH`
829      Specifies the architecture of the build host (e.g. ``i686``). The
830      OpenEmbedded build system sets the value of :term:`BUILD_ARCH` from the
831      machine name reported by the ``uname`` command.
832
833   :term:`BUILD_AS_ARCH`
834      Specifies the architecture-specific assembler flags for the build
835      host. By default, the value of :term:`BUILD_AS_ARCH` is empty.
836
837   :term:`BUILD_CC_ARCH`
838      Specifies the architecture-specific C compiler flags for the build
839      host. By default, the value of :term:`BUILD_CC_ARCH` is empty.
840
841   :term:`BUILD_CCLD`
842      Specifies the linker command to be used for the build host when the C
843      compiler is being used as the linker. By default, :term:`BUILD_CCLD`
844      points to GCC and passes as arguments the value of
845      :term:`BUILD_CC_ARCH`, assuming
846      :term:`BUILD_CC_ARCH` is set.
847
848   :term:`BUILD_CFLAGS`
849      Specifies the flags to pass to the C compiler when building for the
850      build host. When building in the ``-native`` context,
851      :term:`CFLAGS` is set to the value of this variable by
852      default.
853
854   :term:`BUILD_CPPFLAGS`
855      Specifies the flags to pass to the C preprocessor (i.e. to both the C
856      and the C++ compilers) when building for the build host. When
857      building in the ``-native`` context, :term:`CPPFLAGS`
858      is set to the value of this variable by default.
859
860   :term:`BUILD_CXXFLAGS`
861      Specifies the flags to pass to the C++ compiler when building for the
862      build host. When building in the ``-native`` context,
863      :term:`CXXFLAGS` is set to the value of this variable
864      by default.
865
866   :term:`BUILD_FC`
867      Specifies the Fortran compiler command for the build host. By
868      default, :term:`BUILD_FC` points to Gfortran and passes as arguments the
869      value of :term:`BUILD_CC_ARCH`, assuming
870      :term:`BUILD_CC_ARCH` is set.
871
872   :term:`BUILD_LD`
873      Specifies the linker command for the build host. By default,
874      :term:`BUILD_LD` points to the GNU linker (ld) and passes as arguments
875      the value of :term:`BUILD_LD_ARCH`, assuming
876      :term:`BUILD_LD_ARCH` is set.
877
878   :term:`BUILD_LD_ARCH`
879      Specifies architecture-specific linker flags for the build host. By
880      default, the value of :term:`BUILD_LD_ARCH` is empty.
881
882   :term:`BUILD_LDFLAGS`
883      Specifies the flags to pass to the linker when building for the build
884      host. When building in the ``-native`` context,
885      :term:`LDFLAGS` is set to the value of this variable
886      by default.
887
888   :term:`BUILD_OPTIMIZATION`
889      Specifies the optimization flags passed to the C compiler when
890      building for the build host or the SDK. The flags are passed through
891      the :term:`BUILD_CFLAGS` and
892      :term:`BUILDSDK_CFLAGS` default values.
893
894      The default value of the :term:`BUILD_OPTIMIZATION` variable is "-O2
895      -pipe".
896
897   :term:`BUILD_OS`
898      Specifies the operating system in use on the build host (e.g.
899      "linux"). The OpenEmbedded build system sets the value of
900      :term:`BUILD_OS` from the OS reported by the ``uname`` command - the
901      first word, converted to lower-case characters.
902
903   :term:`BUILD_PREFIX`
904      The toolchain binary prefix used for native recipes. The OpenEmbedded
905      build system uses the :term:`BUILD_PREFIX` value to set the
906      :term:`TARGET_PREFIX` when building for
907      ``native`` recipes.
908
909   :term:`BUILD_STRIP`
910      Specifies the command to be used to strip debugging symbols from
911      binaries produced for the build host. By default, :term:`BUILD_STRIP`
912      points to
913      ``${``\ :term:`BUILD_PREFIX`\ ``}strip``.
914
915   :term:`BUILD_SYS`
916      Specifies the system, including the architecture and the operating
917      system, to use when building for the build host (i.e. when building
918      ``native`` recipes).
919
920      The OpenEmbedded build system automatically sets this variable based
921      on :term:`BUILD_ARCH`,
922      :term:`BUILD_VENDOR`, and
923      :term:`BUILD_OS`. You do not need to set the
924      :term:`BUILD_SYS` variable yourself.
925
926   :term:`BUILD_VENDOR`
927      Specifies the vendor name to use when building for the build host.
928      The default value is an empty string ("").
929
930   :term:`BUILDDIR`
931      Points to the location of the :term:`Build Directory`.
932      You can define this directory indirectly through the
933      :ref:`structure-core-script` script by passing in a Build
934      Directory path when you run the script. If you run the script and do
935      not provide a Build Directory path, the :term:`BUILDDIR` defaults to
936      ``build`` in the current directory.
937
938   :term:`BUILDHISTORY_COMMIT`
939      When inheriting the :ref:`buildhistory <ref-classes-buildhistory>`
940      class, this variable specifies whether or not to commit the build
941      history output in a local Git repository. If set to "1", this local
942      repository will be maintained automatically by the ``buildhistory``
943      class and a commit will be created on every build for changes to each
944      top-level subdirectory of the build history output (images, packages,
945      and sdk). If you want to track changes to build history over time,
946      you should set this value to "1".
947
948      By default, the ``buildhistory`` class does not commit the build
949      history output in a local Git repository::
950
951         BUILDHISTORY_COMMIT ?= "0"
952
953   :term:`BUILDHISTORY_COMMIT_AUTHOR`
954      When inheriting the :ref:`buildhistory <ref-classes-buildhistory>`
955      class, this variable specifies the author to use for each Git commit.
956      In order for the :term:`BUILDHISTORY_COMMIT_AUTHOR` variable to work, the
957      :term:`BUILDHISTORY_COMMIT` variable must
958      be set to "1".
959
960      Git requires that the value you provide for the
961      :term:`BUILDHISTORY_COMMIT_AUTHOR` variable takes the form of "name
962      email@host". Providing an email address or host that is not valid
963      does not produce an error.
964
965      By default, the ``buildhistory`` class sets the variable as follows::
966
967         BUILDHISTORY_COMMIT_AUTHOR ?= "buildhistory <buildhistory@${DISTRO}>"
968
969   :term:`BUILDHISTORY_DIR`
970      When inheriting the :ref:`buildhistory <ref-classes-buildhistory>`
971      class, this variable specifies the directory in which build history
972      information is kept. For more information on how the variable works,
973      see the ``buildhistory.class``.
974
975      By default, the ``buildhistory`` class sets the directory as follows::
976
977         BUILDHISTORY_DIR ?= "${TOPDIR}/buildhistory"
978
979   :term:`BUILDHISTORY_FEATURES`
980      When inheriting the :ref:`buildhistory <ref-classes-buildhistory>`
981      class, this variable specifies the build history features to be
982      enabled. For more information on how build history works, see the
983      ":ref:`dev-manual/common-tasks:maintaining build output quality`"
984      section in the Yocto Project Development Tasks Manual.
985
986      You can specify these features in the form of a space-separated list:
987
988      -  *image:* Analysis of the contents of images, which includes the
989         list of installed packages among other things.
990
991      -  *package:* Analysis of the contents of individual packages.
992
993      -  *sdk:* Analysis of the contents of the software development kit
994         (SDK).
995
996      -  *task:* Save output file signatures for
997         :ref:`shared state <overview-manual/concepts:shared state cache>`
998         (sstate) tasks.
999         This saves one file per task and lists the SHA-256 checksums for
1000         each file staged (i.e. the output of the task).
1001
1002      By default, the ``buildhistory`` class enables the following
1003      features::
1004
1005         BUILDHISTORY_FEATURES ?= "image package sdk"
1006
1007   :term:`BUILDHISTORY_IMAGE_FILES`
1008      When inheriting the :ref:`buildhistory <ref-classes-buildhistory>`
1009      class, this variable specifies a list of paths to files copied from
1010      the image contents into the build history directory under an
1011      "image-files" directory in the directory for the image, so that you
1012      can track the contents of each file. The default is to copy
1013      ``/etc/passwd`` and ``/etc/group``, which allows you to monitor for
1014      changes in user and group entries. You can modify the list to include
1015      any file. Specifying an invalid path does not produce an error.
1016      Consequently, you can include files that might not always be present.
1017
1018      By default, the ``buildhistory`` class provides paths to the
1019      following files::
1020
1021         BUILDHISTORY_IMAGE_FILES ?= "/etc/passwd /etc/group"
1022
1023   :term:`BUILDHISTORY_PATH_PREFIX_STRIP`
1024      When inheriting the :ref:`buildhistory <ref-classes-buildhistory>`
1025      class, this variable specifies a common path prefix that should be
1026      stripped off the beginning of paths in the task signature list when the
1027      ``task`` feature is active in :term:`BUILDHISTORY_FEATURES`. This can be
1028      useful when build history is populated from multiple sources that may not
1029      all use the same top level directory.
1030
1031      By default, the ``buildhistory`` class sets the variable as follows::
1032
1033         BUILDHISTORY_PATH_PREFIX_STRIP ?= ""
1034
1035      In this case, no prefixes will be stripped.
1036
1037   :term:`BUILDHISTORY_PUSH_REPO`
1038      When inheriting the :ref:`buildhistory <ref-classes-buildhistory>`
1039      class, this variable optionally specifies a remote repository to
1040      which build history pushes Git changes. In order for
1041      :term:`BUILDHISTORY_PUSH_REPO` to work,
1042      :term:`BUILDHISTORY_COMMIT` must be set to
1043      "1".
1044
1045      The repository should correspond to a remote address that specifies a
1046      repository as understood by Git, or alternatively to a remote name
1047      that you have set up manually using ``git remote`` within the local
1048      repository.
1049
1050      By default, the ``buildhistory`` class sets the variable as follows::
1051
1052         BUILDHISTORY_PUSH_REPO ?= ""
1053
1054   :term:`BUILDSDK_CFLAGS`
1055      Specifies the flags to pass to the C compiler when building for the
1056      SDK. When building in the ``nativesdk-`` context,
1057      :term:`CFLAGS` is set to the value of this variable by
1058      default.
1059
1060   :term:`BUILDSDK_CPPFLAGS`
1061      Specifies the flags to pass to the C pre-processor (i.e. to both the
1062      C and the C++ compilers) when building for the SDK. When building in
1063      the ``nativesdk-`` context, :term:`CPPFLAGS` is set
1064      to the value of this variable by default.
1065
1066   :term:`BUILDSDK_CXXFLAGS`
1067      Specifies the flags to pass to the C++ compiler when building for the
1068      SDK. When building in the ``nativesdk-`` context,
1069      :term:`CXXFLAGS` is set to the value of this variable
1070      by default.
1071
1072   :term:`BUILDSDK_LDFLAGS`
1073      Specifies the flags to pass to the linker when building for the SDK.
1074      When building in the ``nativesdk-`` context,
1075      :term:`LDFLAGS` is set to the value of this variable
1076      by default.
1077
1078   :term:`BUILDSTATS_BASE`
1079      Points to the location of the directory that holds build statistics
1080      when you use and enable the
1081      :ref:`buildstats <ref-classes-buildstats>` class. The
1082      :term:`BUILDSTATS_BASE` directory defaults to
1083      ``${``\ :term:`TMPDIR`\ ``}/buildstats/``.
1084
1085   :term:`BUSYBOX_SPLIT_SUID`
1086      For the BusyBox recipe, specifies whether to split the output
1087      executable file into two parts: one for features that require
1088      ``setuid root``, and one for the remaining features (i.e. those that
1089      do not require ``setuid root``).
1090
1091      The :term:`BUSYBOX_SPLIT_SUID` variable defaults to "1", which results in
1092      splitting the output executable file. Set the variable to "0" to get
1093      a single output executable file.
1094
1095   :term:`CACHE`
1096      Specifies the directory BitBake uses to store a cache of the
1097      :term:`Metadata` so it does not need to be parsed every time
1098      BitBake is started.
1099
1100   :term:`CC`
1101      The minimal command and arguments used to run the C compiler.
1102
1103   :term:`CFLAGS`
1104      Specifies the flags to pass to the C compiler. This variable is
1105      exported to an environment variable and thus made visible to the
1106      software being built during the compilation step.
1107
1108      Default initialization for :term:`CFLAGS` varies depending on what is
1109      being built:
1110
1111      -  :term:`TARGET_CFLAGS` when building for the
1112         target
1113
1114      -  :term:`BUILD_CFLAGS` when building for the
1115         build host (i.e. ``-native``)
1116
1117      -  :term:`BUILDSDK_CFLAGS` when building for
1118         an SDK (i.e. ``nativesdk-``)
1119
1120   :term:`CLASSOVERRIDE`
1121      An internal variable specifying the special class override that
1122      should currently apply (e.g. "class-target", "class-native", and so
1123      forth). The classes that use this variable (e.g.
1124      :ref:`native <ref-classes-native>`,
1125      :ref:`nativesdk <ref-classes-nativesdk>`, and so forth) set the
1126      variable to appropriate values.
1127
1128      .. note::
1129
1130         :term:`CLASSOVERRIDE` gets its default "class-target" value from the
1131         ``bitbake.conf`` file.
1132
1133      As an example, the following override allows you to install extra
1134      files, but only when building for the target::
1135
1136         do_install:append:class-target() {
1137             install my-extra-file ${D}${sysconfdir}
1138         }
1139
1140      Here is an example where ``FOO`` is set to
1141      "native" when building for the build host, and to "other" when not
1142      building for the build host::
1143
1144         FOO:class-native = "native"
1145         FOO = "other"
1146
1147      The underlying mechanism behind :term:`CLASSOVERRIDE` is simply
1148      that it is included in the default value of
1149      :term:`OVERRIDES`.
1150
1151   :term:`CLEANBROKEN`
1152      If set to "1" within a recipe, :term:`CLEANBROKEN` specifies that the
1153      ``make clean`` command does not work for the software being built.
1154      Consequently, the OpenEmbedded build system will not try to run
1155      ``make clean`` during the :ref:`ref-tasks-configure`
1156      task, which is the default behavior.
1157
1158   :term:`COMBINED_FEATURES`
1159      Provides a list of hardware features that are enabled in both
1160      :term:`MACHINE_FEATURES` and
1161      :term:`DISTRO_FEATURES`. This select list of
1162      features contains features that make sense to be controlled both at
1163      the machine and distribution configuration level. For example, the
1164      "bluetooth" feature requires hardware support but should also be
1165      optional at the distribution level, in case the hardware supports
1166      Bluetooth but you do not ever intend to use it.
1167
1168   :term:`COMMON_LICENSE_DIR`
1169      Points to ``meta/files/common-licenses`` in the
1170      :term:`Source Directory`, which is where generic license
1171      files reside.
1172
1173   :term:`COMPATIBLE_HOST`
1174      A regular expression that resolves to one or more hosts (when the
1175      recipe is native) or one or more targets (when the recipe is
1176      non-native) with which a recipe is compatible. The regular expression
1177      is matched against :term:`HOST_SYS`. You can use the
1178      variable to stop recipes from being built for classes of systems with
1179      which the recipes are not compatible. Stopping these builds is
1180      particularly useful with kernels. The variable also helps to increase
1181      parsing speed since the build system skips parsing recipes not
1182      compatible with the current system.
1183
1184   :term:`COMPATIBLE_MACHINE`
1185      A regular expression that resolves to one or more target machines
1186      with which a recipe is compatible. The regular expression is matched
1187      against :term:`MACHINEOVERRIDES`. You can use
1188      the variable to stop recipes from being built for machines with which
1189      the recipes are not compatible. Stopping these builds is particularly
1190      useful with kernels. The variable also helps to increase parsing
1191      speed since the build system skips parsing recipes not compatible
1192      with the current machine.
1193
1194   :term:`COMPLEMENTARY_GLOB`
1195      Defines wildcards to match when installing a list of complementary
1196      packages for all the packages explicitly (or implicitly) installed in
1197      an image.
1198
1199      .. note::
1200
1201         The :term:`COMPLEMENTARY_GLOB` variable uses Unix filename pattern matching
1202         (`fnmatch <https://docs.python.org/3/library/fnmatch.html#module-fnmatch>`__),
1203         which is similar to the Unix style pathname pattern expansion
1204         (`glob <https://docs.python.org/3/library/glob.html>`__).
1205
1206      The resulting list of complementary packages is associated with an
1207      item that can be added to
1208      :term:`IMAGE_FEATURES`. An example usage of
1209      this is the "dev-pkgs" item that when added to :term:`IMAGE_FEATURES`
1210      will install -dev packages (containing headers and other development
1211      files) for every package in the image.
1212
1213      To add a new feature item pointing to a wildcard, use a variable flag
1214      to specify the feature item name and use the value to specify the
1215      wildcard. Here is an example::
1216
1217         COMPLEMENTARY_GLOB[dev-pkgs] = '*-dev'
1218
1219   :term:`COMPONENTS_DIR`
1220      Stores sysroot components for each recipe. The OpenEmbedded build
1221      system uses :term:`COMPONENTS_DIR` when constructing recipe-specific
1222      sysroots for other recipes.
1223
1224      The default is
1225      "``${``\ :term:`STAGING_DIR`\ ``}-components``."
1226      (i.e.
1227      "``${``\ :term:`TMPDIR`\ ``}/sysroots-components``").
1228
1229   :term:`CONF_VERSION`
1230      Tracks the version of the local configuration file (i.e.
1231      ``local.conf``). The value for :term:`CONF_VERSION` increments each time
1232      ``build/conf/`` compatibility changes.
1233
1234   :term:`CONFFILES`
1235      Identifies editable or configurable files that are part of a package.
1236      If the Package Management System (PMS) is being used to update
1237      packages on the target system, it is possible that configuration
1238      files you have changed after the original installation and that you
1239      now want to remain unchanged are overwritten. In other words,
1240      editable files might exist in the package that you do not want reset
1241      as part of the package update process. You can use the :term:`CONFFILES`
1242      variable to list the files in the package that you wish to prevent
1243      the PMS from overwriting during this update process.
1244
1245      To use the :term:`CONFFILES` variable, provide a package name override
1246      that identifies the resulting package. Then, provide a
1247      space-separated list of files. Here is an example::
1248
1249         CONFFILES:${PN} += "${sysconfdir}/file1 \
1250             ${sysconfdir}/file2 ${sysconfdir}/file3"
1251
1252      There is a relationship between the :term:`CONFFILES` and :term:`FILES`
1253      variables. The files listed within :term:`CONFFILES` must be a subset of
1254      the files listed within :term:`FILES`. Because the configuration files
1255      you provide with :term:`CONFFILES` are simply being identified so that
1256      the PMS will not overwrite them, it makes sense that the files must
1257      already be included as part of the package through the :term:`FILES`
1258      variable.
1259
1260      .. note::
1261
1262         When specifying paths as part of the :term:`CONFFILES` variable, it is
1263         good practice to use appropriate path variables.
1264         For example, ``${sysconfdir}`` rather than ``/etc`` or ``${bindir}``
1265         rather than ``/usr/bin``. You can find a list of these variables at
1266         the top of the ``meta/conf/bitbake.conf`` file in the
1267         :term:`Source Directory`.
1268
1269   :term:`CONFIG_INITRAMFS_SOURCE`
1270      Identifies the initial RAM filesystem (initramfs) source files. The
1271      OpenEmbedded build system receives and uses this kernel Kconfig
1272      variable as an environment variable. By default, the variable is set
1273      to null ("").
1274
1275      The :term:`CONFIG_INITRAMFS_SOURCE` can be either a single cpio archive
1276      with a ``.cpio`` suffix or a space-separated list of directories and
1277      files for building the initramfs image. A cpio archive should contain
1278      a filesystem archive to be used as an initramfs image. Directories
1279      should contain a filesystem layout to be included in the initramfs
1280      image. Files should contain entries according to the format described
1281      by the ``usr/gen_init_cpio`` program in the kernel tree.
1282
1283      If you specify multiple directories and files, the initramfs image
1284      will be the aggregate of all of them.
1285
1286      For information on creating an initramfs, see the
1287      ":ref:`dev-manual/common-tasks:building an initial ram filesystem (initramfs) image`" section
1288      in the Yocto Project Development Tasks Manual.
1289
1290   :term:`CONFIG_SITE`
1291      A list of files that contains ``autoconf`` test results relevant to
1292      the current build. This variable is used by the Autotools utilities
1293      when running ``configure``.
1294
1295   :term:`CONFIGURE_FLAGS`
1296      The minimal arguments for GNU configure.
1297
1298   :term:`CONFLICT_DISTRO_FEATURES`
1299      When inheriting the
1300      :ref:`features_check <ref-classes-features_check>`
1301      class, this variable identifies distribution features that would be
1302      in conflict should the recipe be built. In other words, if the
1303      :term:`CONFLICT_DISTRO_FEATURES` variable lists a feature that also
1304      appears in :term:`DISTRO_FEATURES` within the current configuration, then
1305      the recipe will be skipped, and if the build system attempts to build
1306      the recipe then an error will be triggered.
1307
1308   :term:`COPYLEFT_LICENSE_EXCLUDE`
1309      A space-separated list of licenses to exclude from the source
1310      archived by the :ref:`archiver <ref-classes-archiver>` class. In
1311      other words, if a license in a recipe's
1312      :term:`LICENSE` value is in the value of
1313      :term:`COPYLEFT_LICENSE_EXCLUDE`, then its source is not archived by the
1314      class.
1315
1316      .. note::
1317
1318         The :term:`COPYLEFT_LICENSE_EXCLUDE` variable takes precedence over the
1319         :term:`COPYLEFT_LICENSE_INCLUDE` variable.
1320
1321      The default value, which is "CLOSED Proprietary", for
1322      :term:`COPYLEFT_LICENSE_EXCLUDE` is set by the
1323      :ref:`copyleft_filter <ref-classes-copyleft_filter>` class, which
1324      is inherited by the ``archiver`` class.
1325
1326   :term:`COPYLEFT_LICENSE_INCLUDE`
1327      A space-separated list of licenses to include in the source archived
1328      by the :ref:`archiver <ref-classes-archiver>` class. In other
1329      words, if a license in a recipe's :term:`LICENSE`
1330      value is in the value of :term:`COPYLEFT_LICENSE_INCLUDE`, then its
1331      source is archived by the class.
1332
1333      The default value is set by the
1334      :ref:`copyleft_filter <ref-classes-copyleft_filter>` class, which
1335      is inherited by the ``archiver`` class. The default value includes
1336      "GPL*", "LGPL*", and "AGPL*".
1337
1338   :term:`COPYLEFT_PN_EXCLUDE`
1339      A list of recipes to exclude in the source archived by the
1340      :ref:`archiver <ref-classes-archiver>` class. The
1341      :term:`COPYLEFT_PN_EXCLUDE` variable overrides the license inclusion and
1342      exclusion caused through the
1343      :term:`COPYLEFT_LICENSE_INCLUDE` and
1344      :term:`COPYLEFT_LICENSE_EXCLUDE`
1345      variables, respectively.
1346
1347      The default value, which is "" indicating to not explicitly exclude
1348      any recipes by name, for :term:`COPYLEFT_PN_EXCLUDE` is set by the
1349      :ref:`copyleft_filter <ref-classes-copyleft_filter>` class, which
1350      is inherited by the ``archiver`` class.
1351
1352   :term:`COPYLEFT_PN_INCLUDE`
1353      A list of recipes to include in the source archived by the
1354      :ref:`archiver <ref-classes-archiver>` class. The
1355      :term:`COPYLEFT_PN_INCLUDE` variable overrides the license inclusion and
1356      exclusion caused through the
1357      :term:`COPYLEFT_LICENSE_INCLUDE` and
1358      :term:`COPYLEFT_LICENSE_EXCLUDE`
1359      variables, respectively.
1360
1361      The default value, which is "" indicating to not explicitly include
1362      any recipes by name, for :term:`COPYLEFT_PN_INCLUDE` is set by the
1363      :ref:`copyleft_filter <ref-classes-copyleft_filter>` class, which
1364      is inherited by the ``archiver`` class.
1365
1366   :term:`COPYLEFT_RECIPE_TYPES`
1367      A space-separated list of recipe types to include in the source
1368      archived by the :ref:`archiver <ref-classes-archiver>` class.
1369      Recipe types are ``target``, ``native``, ``nativesdk``, ``cross``,
1370      ``crosssdk``, and ``cross-canadian``.
1371
1372      The default value, which is "target*", for :term:`COPYLEFT_RECIPE_TYPES`
1373      is set by the :ref:`copyleft_filter <ref-classes-copyleft_filter>`
1374      class, which is inherited by the ``archiver`` class.
1375
1376   :term:`COPY_LIC_DIRS`
1377      If set to "1" along with the
1378      :term:`COPY_LIC_MANIFEST` variable, the
1379      OpenEmbedded build system copies into the image the license files,
1380      which are located in ``/usr/share/common-licenses``, for each
1381      package. The license files are placed in directories within the image
1382      itself during build time.
1383
1384      .. note::
1385
1386         The :term:`COPY_LIC_DIRS` does not offer a path for adding licenses for
1387         newly installed packages to an image, which might be most suitable for
1388         read-only filesystems that cannot be upgraded. See the
1389         :term:`LICENSE_CREATE_PACKAGE` variable for additional information.
1390         You can also reference the ":ref:`dev-manual/common-tasks:providing license text`"
1391         section in the Yocto Project Development Tasks Manual for
1392         information on providing license text.
1393
1394   :term:`COPY_LIC_MANIFEST`
1395      If set to "1", the OpenEmbedded build system copies the license
1396      manifest for the image to
1397      ``/usr/share/common-licenses/license.manifest`` within the image
1398      itself during build time.
1399
1400      .. note::
1401
1402         The :term:`COPY_LIC_MANIFEST` does not offer a path for adding licenses for
1403         newly installed packages to an image, which might be most suitable for
1404         read-only filesystems that cannot be upgraded. See the
1405         :term:`LICENSE_CREATE_PACKAGE` variable for additional information.
1406         You can also reference the ":ref:`dev-manual/common-tasks:providing license text`"
1407         section in the Yocto Project Development Tasks Manual for
1408         information on providing license text.
1409
1410   :term:`CORE_IMAGE_EXTRA_INSTALL`
1411      Specifies the list of packages to be added to the image. You should
1412      only set this variable in the ``local.conf`` configuration file found
1413      in the :term:`Build Directory`.
1414
1415      This variable replaces ``POKY_EXTRA_INSTALL``, which is no longer
1416      supported.
1417
1418   :term:`COREBASE`
1419      Specifies the parent directory of the OpenEmbedded-Core Metadata
1420      layer (i.e. ``meta``).
1421
1422      It is an important distinction that :term:`COREBASE` points to the parent
1423      of this layer and not the layer itself. Consider an example where you
1424      have cloned the Poky Git repository and retained the ``poky`` name
1425      for your local copy of the repository. In this case, :term:`COREBASE`
1426      points to the ``poky`` folder because it is the parent directory of
1427      the ``poky/meta`` layer.
1428
1429   :term:`COREBASE_FILES`
1430      Lists files from the :term:`COREBASE` directory that
1431      should be copied other than the layers listed in the
1432      ``bblayers.conf`` file. The :term:`COREBASE_FILES` variable allows
1433      to copy metadata from the OpenEmbedded build system
1434      into the extensible SDK.
1435
1436      Explicitly listing files in :term:`COREBASE` is needed because it
1437      typically contains build directories and other files that should not
1438      normally be copied into the extensible SDK. Consequently, the value
1439      of :term:`COREBASE_FILES` is used in order to only copy the files that
1440      are actually needed.
1441
1442   :term:`CPP`
1443      The minimal command and arguments used to run the C preprocessor.
1444
1445   :term:`CPPFLAGS`
1446      Specifies the flags to pass to the C pre-processor (i.e. to both the
1447      C and the C++ compilers). This variable is exported to an environment
1448      variable and thus made visible to the software being built during the
1449      compilation step.
1450
1451      Default initialization for :term:`CPPFLAGS` varies depending on what is
1452      being built:
1453
1454      -  :term:`TARGET_CPPFLAGS` when building for
1455         the target
1456
1457      -  :term:`BUILD_CPPFLAGS` when building for the
1458         build host (i.e. ``-native``)
1459
1460      -  :term:`BUILDSDK_CPPFLAGS` when building
1461         for an SDK (i.e. ``nativesdk-``)
1462
1463   :term:`CROSS_COMPILE`
1464      The toolchain binary prefix for the target tools. The
1465      :term:`CROSS_COMPILE` variable is the same as the
1466      :term:`TARGET_PREFIX` variable.
1467
1468      .. note::
1469
1470         The OpenEmbedded build system sets the :term:`CROSS_COMPILE`
1471         variable only in certain contexts (e.g. when building for kernel
1472         and kernel module recipes).
1473
1474   :term:`CVE_CHECK_PN_WHITELIST`
1475      The list of package names (:term:`PN`) for which
1476      CVEs (Common Vulnerabilities and Exposures) are ignored.
1477
1478   :term:`CVE_CHECK_WHITELIST`
1479      The list of CVE IDs which are ignored. Here is
1480      an example from the :oe_layerindex:`Python3 recipe</layerindex/recipe/23823>`::
1481
1482         # This is windows only issue.
1483         CVE_CHECK_WHITELIST += "CVE-2020-15523"
1484
1485   :term:`CVE_PRODUCT`
1486      In a recipe, defines the name used to match the recipe name
1487      against the name in the upstream `NIST CVE database <https://nvd.nist.gov/>`__.
1488
1489      The default is ${:term:`BPN`}. If it does not match the name in the NIST CVE
1490      database or matches with multiple entries in the database, the default
1491      value needs to be changed.
1492
1493      Here is an example from the :oe_layerindex:`Berkeley DB recipe </layerindex/recipe/544>`::
1494
1495         CVE_PRODUCT = "oracle_berkeley_db berkeley_db"
1496
1497   :term:`CVSDIR`
1498      The directory in which files checked out under the CVS system are
1499      stored.
1500
1501   :term:`CXX`
1502      The minimal command and arguments used to run the C++ compiler.
1503
1504   :term:`CXXFLAGS`
1505      Specifies the flags to pass to the C++ compiler. This variable is
1506      exported to an environment variable and thus made visible to the
1507      software being built during the compilation step.
1508
1509      Default initialization for :term:`CXXFLAGS` varies depending on what is
1510      being built:
1511
1512      -  :term:`TARGET_CXXFLAGS` when building for
1513         the target
1514
1515      -  :term:`BUILD_CXXFLAGS` when building for the
1516         build host (i.e. ``-native``)
1517
1518      -  :term:`BUILDSDK_CXXFLAGS` when building
1519         for an SDK (i.e. ``nativesdk-``)
1520
1521   :term:`D`
1522      The destination directory. The location in the :term:`Build Directory`
1523      where components are installed by the
1524      :ref:`ref-tasks-install` task. This location defaults
1525      to::
1526
1527         ${WORKDIR}/image
1528
1529      .. note::
1530
1531         Tasks that read from or write to this directory should run under
1532         :ref:`fakeroot <overview-manual/concepts:fakeroot and pseudo>`.
1533
1534   :term:`DATE`
1535      The date the build was started. Dates appear using the year, month,
1536      and day (YMD) format (e.g. "20150209" for February 9th, 2015).
1537
1538   :term:`DATETIME`
1539      The date and time on which the current build started. The format is
1540      suitable for timestamps.
1541
1542   :term:`DEBIAN_NOAUTONAME`
1543      When the :ref:`debian <ref-classes-debian>` class is inherited,
1544      which is the default behavior, :term:`DEBIAN_NOAUTONAME` specifies a
1545      particular package should not be renamed according to Debian library
1546      package naming. You must use the package name as an override when you
1547      set this variable. Here is an example from the ``fontconfig`` recipe::
1548
1549         DEBIAN_NOAUTONAME:fontconfig-utils = "1"
1550
1551   :term:`DEBIANNAME`
1552      When the :ref:`debian <ref-classes-debian>` class is inherited,
1553      which is the default behavior, :term:`DEBIANNAME` allows you to override
1554      the library name for an individual package. Overriding the library
1555      name in these cases is rare. You must use the package name as an
1556      override when you set this variable. Here is an example from the
1557      ``dbus`` recipe::
1558
1559         DEBIANNAME:${PN} = "dbus-1"
1560
1561   :term:`DEBUG_BUILD`
1562      Specifies to build packages with debugging information. This
1563      influences the value of the :term:`SELECTED_OPTIMIZATION` variable.
1564
1565   :term:`DEBUG_OPTIMIZATION`
1566      The options to pass in :term:`TARGET_CFLAGS` and :term:`CFLAGS` when
1567      compiling a system for debugging. This variable defaults to "-O
1568      -fno-omit-frame-pointer ${DEBUG_FLAGS} -pipe".
1569
1570   :term:`DEFAULT_PREFERENCE`
1571      Specifies a weak bias for recipe selection priority.
1572
1573      The most common usage of this is variable is to set it to "-1" within
1574      a recipe for a development version of a piece of software. Using the
1575      variable in this way causes the stable version of the recipe to build
1576      by default in the absence of :term:`PREFERRED_VERSION` being used to
1577      build the development version.
1578
1579      .. note::
1580
1581         The bias provided by :term:`DEFAULT_PREFERENCE` is weak and is overridden
1582         by :term:`BBFILE_PRIORITY` if that variable is different between two
1583         layers that contain different versions of the same recipe.
1584
1585   :term:`DEFAULTTUNE`
1586      The default CPU and Application Binary Interface (ABI) tunings (i.e.
1587      the "tune") used by the OpenEmbedded build system. The
1588      :term:`DEFAULTTUNE` helps define
1589      :term:`TUNE_FEATURES`.
1590
1591      The default tune is either implicitly or explicitly set by the
1592      machine (:term:`MACHINE`). However, you can override
1593      the setting using available tunes as defined with
1594      :term:`AVAILTUNES`.
1595
1596   :term:`DEPENDS`
1597      Lists a recipe's build-time dependencies. These are dependencies on
1598      other recipes whose contents (e.g. headers and shared libraries) are
1599      needed by the recipe at build time.
1600
1601      As an example, consider a recipe ``foo`` that contains the following
1602      assignment::
1603
1604          DEPENDS = "bar"
1605
1606      The practical effect of the previous
1607      assignment is that all files installed by bar will be available in
1608      the appropriate staging sysroot, given by the
1609      :term:`STAGING_DIR* <STAGING_DIR>` variables, by the time the
1610      :ref:`ref-tasks-configure` task for ``foo`` runs.
1611      This mechanism is implemented by having ``do_configure`` depend on
1612      the :ref:`ref-tasks-populate_sysroot` task of
1613      each recipe listed in :term:`DEPENDS`, through a
1614      ``[``\ :ref:`deptask <bitbake:bitbake-user-manual/bitbake-user-manual-metadata:variable flags>`\ ``]``
1615      declaration in the :ref:`base <ref-classes-base>` class.
1616
1617      .. note::
1618
1619         It seldom is necessary to reference, for example, :term:`STAGING_DIR_HOST`
1620         explicitly. The standard classes and build-related variables are
1621         configured to automatically use the appropriate staging sysroots.
1622
1623      As another example, :term:`DEPENDS` can also be used to add utilities
1624      that run on the build machine during the build. For example, a recipe
1625      that makes use of a code generator built by the recipe ``codegen``
1626      might have the following::
1627
1628         DEPENDS = "codegen-native"
1629
1630      For more
1631      information, see the :ref:`native <ref-classes-native>` class and
1632      the :term:`EXTRANATIVEPATH` variable.
1633
1634      .. note::
1635
1636         -  :term:`DEPENDS` is a list of recipe names. Or, to be more precise,
1637            it is a list of :term:`PROVIDES` names, which
1638            usually match recipe names. Putting a package name such as
1639            "foo-dev" in :term:`DEPENDS` does not make sense. Use "foo"
1640            instead, as this will put files from all the packages that make
1641            up ``foo``, which includes those from ``foo-dev``, into the
1642            sysroot.
1643
1644         -  One recipe having another recipe in :term:`DEPENDS` does not by
1645            itself add any runtime dependencies between the packages
1646            produced by the two recipes. However, as explained in the
1647            ":ref:`overview-manual/concepts:automatically added runtime dependencies`"
1648            section in the Yocto Project Overview and Concepts Manual,
1649            runtime dependencies will often be added automatically, meaning
1650            :term:`DEPENDS` alone is sufficient for most recipes.
1651
1652         -  Counterintuitively, :term:`DEPENDS` is often necessary even for
1653            recipes that install precompiled components. For example, if
1654            ``libfoo`` is a precompiled library that links against
1655            ``libbar``, then linking against ``libfoo`` requires both
1656            ``libfoo`` and ``libbar`` to be available in the sysroot.
1657            Without a :term:`DEPENDS` from the recipe that installs ``libfoo``
1658            to the recipe that installs ``libbar``, other recipes might
1659            fail to link against ``libfoo``.
1660
1661      For information on runtime dependencies, see the
1662      :term:`RDEPENDS` variable. You can also see the
1663      ":ref:`bitbake:bitbake-user-manual/bitbake-user-manual-metadata:tasks`" and
1664      ":ref:`bitbake:bitbake-user-manual/bitbake-user-manual-execution:dependencies`" sections in the
1665      BitBake User Manual for additional information on tasks and
1666      dependencies.
1667
1668   :term:`DEPLOY_DIR`
1669      Points to the general area that the OpenEmbedded build system uses to
1670      place images, packages, SDKs, and other output files that are ready
1671      to be used outside of the build system. By default, this directory
1672      resides within the :term:`Build Directory` as
1673      ``${TMPDIR}/deploy``.
1674
1675      For more information on the structure of the Build Directory, see
1676      ":ref:`ref-manual/structure:the build directory - \`\`build/\`\``" section.
1677      For more detail on the contents of the ``deploy`` directory, see the
1678      ":ref:`overview-manual/concepts:images`",
1679      ":ref:`overview-manual/concepts:package feeds`", and
1680      ":ref:`overview-manual/concepts:application development sdk`" sections all in the
1681      Yocto Project Overview and Concepts Manual.
1682
1683   :term:`DEPLOY_DIR_DEB`
1684      Points to the area that the OpenEmbedded build system uses to place
1685      Debian packages that are ready to be used outside of the build
1686      system. This variable applies only when
1687      :term:`PACKAGE_CLASSES` contains
1688      "package_deb".
1689
1690      The BitBake configuration file initially defines the
1691      :term:`DEPLOY_DIR_DEB` variable as a sub-folder of
1692      :term:`DEPLOY_DIR`::
1693
1694         DEPLOY_DIR_DEB = "${DEPLOY_DIR}/deb"
1695
1696      The :ref:`package_deb <ref-classes-package_deb>` class uses the
1697      :term:`DEPLOY_DIR_DEB` variable to make sure the
1698      :ref:`ref-tasks-package_write_deb` task
1699      writes Debian packages into the appropriate folder. For more
1700      information on how packaging works, see the
1701      ":ref:`overview-manual/concepts:package feeds`" section
1702      in the Yocto Project Overview and Concepts Manual.
1703
1704   :term:`DEPLOY_DIR_IMAGE`
1705      Points to the area that the OpenEmbedded build system uses to place
1706      images and other associated output files that are ready to be
1707      deployed onto the target machine. The directory is machine-specific
1708      as it contains the ``${MACHINE}`` name. By default, this directory
1709      resides within the :term:`Build Directory` as
1710      ``${DEPLOY_DIR}/images/${MACHINE}/``.
1711
1712      It must not be used directly in recipes when deploying files. Instead,
1713      it's only useful when a recipe needs to "read" a file already deployed
1714      by a dependency. So, it should be filled with the contents of
1715      :term:`DEPLOYDIR` by the :ref:`deploy <ref-classes-deploy>` class or
1716      with the contents of :term:`IMGDEPLOYDIR` by the :ref:`image
1717      <ref-classes-image>` class.
1718
1719      For more information on the structure of the Build Directory, see
1720      ":ref:`ref-manual/structure:the build directory - \`\`build/\`\``" section.
1721      For more detail on the contents of the ``deploy`` directory, see the
1722      ":ref:`overview-manual/concepts:images`" and
1723      ":ref:`overview-manual/concepts:application development sdk`" sections both in
1724      the Yocto Project Overview and Concepts Manual.
1725
1726   :term:`DEPLOY_DIR_IPK`
1727      Points to the area that the OpenEmbedded build system uses to place
1728      IPK packages that are ready to be used outside of the build system.
1729      This variable applies only when
1730      :term:`PACKAGE_CLASSES` contains
1731      "package_ipk".
1732
1733      The BitBake configuration file initially defines this variable as a
1734      sub-folder of :term:`DEPLOY_DIR`::
1735
1736         DEPLOY_DIR_IPK = "${DEPLOY_DIR}/ipk"
1737
1738      The :ref:`package_ipk <ref-classes-package_ipk>` class uses the
1739      :term:`DEPLOY_DIR_IPK` variable to make sure the
1740      :ref:`ref-tasks-package_write_ipk` task
1741      writes IPK packages into the appropriate folder. For more information
1742      on how packaging works, see the
1743      ":ref:`overview-manual/concepts:package feeds`" section
1744      in the Yocto Project Overview and Concepts Manual.
1745
1746   :term:`DEPLOY_DIR_RPM`
1747      Points to the area that the OpenEmbedded build system uses to place
1748      RPM packages that are ready to be used outside of the build system.
1749      This variable applies only when
1750      :term:`PACKAGE_CLASSES` contains
1751      "package_rpm".
1752
1753      The BitBake configuration file initially defines this variable as a
1754      sub-folder of :term:`DEPLOY_DIR`::
1755
1756         DEPLOY_DIR_RPM = "${DEPLOY_DIR}/rpm"
1757
1758      The :ref:`package_rpm <ref-classes-package_rpm>` class uses the
1759      :term:`DEPLOY_DIR_RPM` variable to make sure the
1760      :ref:`ref-tasks-package_write_rpm` task
1761      writes RPM packages into the appropriate folder. For more information
1762      on how packaging works, see the
1763      ":ref:`overview-manual/concepts:package feeds`" section
1764      in the Yocto Project Overview and Concepts Manual.
1765
1766   :term:`DEPLOY_DIR_TAR`
1767      Points to the area that the OpenEmbedded build system uses to place
1768      tarballs that are ready to be used outside of the build system. This
1769      variable applies only when
1770      :term:`PACKAGE_CLASSES` contains
1771      "package_tar".
1772
1773      The BitBake configuration file initially defines this variable as a
1774      sub-folder of :term:`DEPLOY_DIR`::
1775
1776         DEPLOY_DIR_TAR = "${DEPLOY_DIR}/tar"
1777
1778      The :ref:`package_tar <ref-classes-package_tar>` class uses the
1779      :term:`DEPLOY_DIR_TAR` variable to make sure the
1780      :ref:`ref-tasks-package_write_tar` task
1781      writes TAR packages into the appropriate folder. For more information
1782      on how packaging works, see the
1783      ":ref:`overview-manual/concepts:package feeds`" section
1784      in the Yocto Project Overview and Concepts Manual.
1785
1786   :term:`DEPLOYDIR`
1787      When inheriting the :ref:`deploy <ref-classes-deploy>` class, the
1788      :term:`DEPLOYDIR` points to a temporary work area for deployed files that
1789      is set in the ``deploy`` class as follows::
1790
1791         DEPLOYDIR = "${WORKDIR}/deploy-${PN}"
1792
1793      Recipes inheriting the ``deploy`` class should copy files to be
1794      deployed into :term:`DEPLOYDIR`, and the class will take care of copying
1795      them into :term:`DEPLOY_DIR_IMAGE`
1796      afterwards.
1797
1798   :term:`DESCRIPTION`
1799      The package description used by package managers. If not set,
1800      :term:`DESCRIPTION` takes the value of the :term:`SUMMARY`
1801      variable.
1802
1803   :term:`DISTRO`
1804      The short name of the distribution. For information on the long name
1805      of the distribution, see the :term:`DISTRO_NAME`
1806      variable.
1807
1808      The :term:`DISTRO` variable corresponds to a distribution configuration
1809      file whose root name is the same as the variable's argument and whose
1810      filename extension is ``.conf``. For example, the distribution
1811      configuration file for the Poky distribution is named ``poky.conf``
1812      and resides in the ``meta-poky/conf/distro`` directory of the
1813      :term:`Source Directory`.
1814
1815      Within that ``poky.conf`` file, the :term:`DISTRO` variable is set as
1816      follows::
1817
1818         DISTRO = "poky"
1819
1820      Distribution configuration files are located in a ``conf/distro``
1821      directory within the :term:`Metadata` that contains the
1822      distribution configuration. The value for :term:`DISTRO` must not contain
1823      spaces, and is typically all lower-case.
1824
1825      .. note::
1826
1827         If the :term:`DISTRO` variable is blank, a set of default configurations
1828         are used, which are specified within
1829         ``meta/conf/distro/defaultsetup.conf`` also in the Source Directory.
1830
1831   :term:`DISTRO_CODENAME`
1832      Specifies a codename for the distribution being built.
1833
1834   :term:`DISTRO_EXTRA_RDEPENDS`
1835      Specifies a list of distro-specific packages to add to all images.
1836      This variable takes affect through ``packagegroup-base`` so the
1837      variable only really applies to the more full-featured images that
1838      include ``packagegroup-base``. You can use this variable to keep
1839      distro policy out of generic images. As with all other distro
1840      variables, you set this variable in the distro ``.conf`` file.
1841
1842   :term:`DISTRO_EXTRA_RRECOMMENDS`
1843      Specifies a list of distro-specific packages to add to all images if
1844      the packages exist. The packages might not exist or be empty (e.g.
1845      kernel modules). The list of packages are automatically installed but
1846      you can remove them.
1847
1848   :term:`DISTRO_FEATURES`
1849      The software support you want in your distribution for various
1850      features. You define your distribution features in the distribution
1851      configuration file.
1852
1853      In most cases, the presence or absence of a feature in
1854      :term:`DISTRO_FEATURES` is translated to the appropriate option supplied
1855      to the configure script during the
1856      :ref:`ref-tasks-configure` task for recipes that
1857      optionally support the feature. For example, specifying "x11" in
1858      :term:`DISTRO_FEATURES`, causes every piece of software built for the
1859      target that can optionally support X11 to have its X11 support
1860      enabled.
1861
1862      Two more examples are Bluetooth and NFS support. For a more complete
1863      list of features that ships with the Yocto Project and that you can
1864      provide with this variable, see the ":ref:`ref-features-distro`" section.
1865
1866   :term:`DISTRO_FEATURES_BACKFILL`
1867      Features to be added to :term:`DISTRO_FEATURES` if not also present in
1868      :term:`DISTRO_FEATURES_BACKFILL_CONSIDERED`.
1869
1870      This variable is set in the ``meta/conf/bitbake.conf`` file. It is
1871      not intended to be user-configurable. It is best to just reference
1872      the variable to see which distro features are being backfilled for
1873      all distro configurations. See the ":ref:`ref-features-backfill`" section
1874      for more information.
1875
1876   :term:`DISTRO_FEATURES_BACKFILL_CONSIDERED`
1877      Features from :term:`DISTRO_FEATURES_BACKFILL` that should not be
1878      backfilled (i.e. added to :term:`DISTRO_FEATURES`) during the build. See
1879      the ":ref:`ref-features-backfill`" section for more information.
1880
1881   :term:`DISTRO_FEATURES_DEFAULT`
1882      A convenience variable that gives you the default list of distro
1883      features with the exception of any features specific to the C library
1884      (``libc``).
1885
1886      When creating a custom distribution, you might find it useful to be
1887      able to reuse the default
1888      :term:`DISTRO_FEATURES` options without the
1889      need to write out the full set. Here is an example that uses
1890      :term:`DISTRO_FEATURES_DEFAULT` from a custom distro configuration file::
1891
1892         DISTRO_FEATURES ?= "${DISTRO_FEATURES_DEFAULT} myfeature"
1893
1894   :term:`DISTRO_FEATURES_FILTER_NATIVE`
1895      Specifies a list of features that if present in the target
1896      :term:`DISTRO_FEATURES` value should be
1897      included in :term:`DISTRO_FEATURES` when building native recipes. This
1898      variable is used in addition to the features filtered using the
1899      :term:`DISTRO_FEATURES_NATIVE`
1900      variable.
1901
1902   :term:`DISTRO_FEATURES_FILTER_NATIVESDK`
1903      Specifies a list of features that if present in the target
1904      :term:`DISTRO_FEATURES` value should be
1905      included in :term:`DISTRO_FEATURES` when building nativesdk recipes. This
1906      variable is used in addition to the features filtered using the
1907      :term:`DISTRO_FEATURES_NATIVESDK`
1908      variable.
1909
1910   :term:`DISTRO_FEATURES_NATIVE`
1911      Specifies a list of features that should be included in
1912      :term:`DISTRO_FEATURES` when building native
1913      recipes. This variable is used in addition to the features filtered
1914      using the
1915      :term:`DISTRO_FEATURES_FILTER_NATIVE`
1916      variable.
1917
1918   :term:`DISTRO_FEATURES_NATIVESDK`
1919      Specifies a list of features that should be included in
1920      :term:`DISTRO_FEATURES` when building
1921      nativesdk recipes. This variable is used in addition to the features
1922      filtered using the
1923      :term:`DISTRO_FEATURES_FILTER_NATIVESDK`
1924      variable.
1925
1926   :term:`DISTRO_NAME`
1927      The long name of the distribution. For information on the short name
1928      of the distribution, see the :term:`DISTRO` variable.
1929
1930      The :term:`DISTRO_NAME` variable corresponds to a distribution
1931      configuration file whose root name is the same as the variable's
1932      argument and whose filename extension is ``.conf``. For example, the
1933      distribution configuration file for the Poky distribution is named
1934      ``poky.conf`` and resides in the ``meta-poky/conf/distro`` directory
1935      of the :term:`Source Directory`.
1936
1937      Within that ``poky.conf`` file, the :term:`DISTRO_NAME` variable is set
1938      as follows::
1939
1940         DISTRO_NAME = "Poky (Yocto Project Reference Distro)"
1941
1942      Distribution configuration files are located in a ``conf/distro``
1943      directory within the :term:`Metadata` that contains the
1944      distribution configuration.
1945
1946      .. note::
1947
1948         If the :term:`DISTRO_NAME` variable is blank, a set of default
1949         configurations are used, which are specified within
1950         ``meta/conf/distro/defaultsetup.conf`` also in the Source Directory.
1951
1952   :term:`DISTRO_VERSION`
1953      The version of the distribution.
1954
1955   :term:`DISTROOVERRIDES`
1956      A colon-separated list of overrides specific to the current
1957      distribution. By default, this list includes the value of
1958      :term:`DISTRO`.
1959
1960      You can extend :term:`DISTROOVERRIDES` to add extra overrides that should
1961      apply to the distribution.
1962
1963      The underlying mechanism behind :term:`DISTROOVERRIDES` is simply that it
1964      is included in the default value of
1965      :term:`OVERRIDES`.
1966
1967   :term:`DISTUTILS_SETUP_PATH`
1968      When used by recipes that inherit the
1969      :ref:`distutils3 <ref-classes-distutils3>` or
1970      :ref:`setuptools3 <ref-classes-setuptools3>` class, this variable should
1971      be used to specify the directory in which the ``setup.py`` file is
1972      located if it is not at the root of the source tree (as specified by
1973      :term:`S`). For example, in a recipe where the sources are fetched from
1974      a Git repository and ``setup.py`` is in a ``python/pythonmodule``
1975      subdirectory, you would have this::
1976
1977         S = "${WORKDIR}/git"
1978         DISTUTILS_SETUP_PATH = "${S}/python/pythonmodule"
1979
1980   :term:`DL_DIR`
1981      The central download directory used by the build process to store
1982      downloads. By default, :term:`DL_DIR` gets files suitable for mirroring
1983      for everything except Git repositories. If you want tarballs of Git
1984      repositories, use the
1985      :term:`BB_GENERATE_MIRROR_TARBALLS`
1986      variable.
1987
1988      You can set this directory by defining the :term:`DL_DIR` variable in the
1989      ``conf/local.conf`` file. This directory is self-maintaining and you
1990      should not have to touch it. By default, the directory is
1991      ``downloads`` in the :term:`Build Directory`.
1992      ::
1993
1994         #DL_DIR ?= "${TOPDIR}/downloads"
1995
1996      To specify a different download directory,
1997      simply remove the comment from the line and provide your directory.
1998
1999      During a first build, the system downloads many different source code
2000      tarballs from various upstream projects. Downloading can take a
2001      while, particularly if your network connection is slow. Tarballs are
2002      all stored in the directory defined by :term:`DL_DIR` and the build
2003      system looks there first to find source tarballs.
2004
2005      .. note::
2006
2007         When wiping and rebuilding, you can preserve this directory to
2008         speed up this part of subsequent builds.
2009
2010      You can safely share this directory between multiple builds on the
2011      same development machine. For additional information on how the build
2012      process gets source files when working behind a firewall or proxy
2013      server, see this specific question in the ":doc:`faq`"
2014      chapter. You can also refer to the
2015      ":yocto_wiki:`Working Behind a Network Proxy </Working_Behind_a_Network_Proxy>`"
2016      Wiki page.
2017
2018   :term:`DOC_COMPRESS`
2019      When inheriting the :ref:`compress_doc <ref-classes-compress_doc>`
2020      class, this variable sets the compression policy used when the
2021      OpenEmbedded build system compresses man pages and info pages. By
2022      default, the compression method used is gz (gzip). Other policies
2023      available are xz and bz2.
2024
2025      For information on policies and on how to use this variable, see the
2026      comments in the ``meta/classes/compress_doc.bbclass`` file.
2027
2028   :term:`EFI_PROVIDER`
2029      When building bootable images (i.e. where ``hddimg``, ``iso``, or
2030      ``wic.vmdk`` is in :term:`IMAGE_FSTYPES`), the
2031      :term:`EFI_PROVIDER` variable specifies the EFI bootloader to use. The
2032      default is "grub-efi", but "systemd-boot" can be used instead.
2033
2034      See the :ref:`systemd-boot <ref-classes-systemd-boot>` and
2035      :ref:`image-live <ref-classes-image-live>` classes for more
2036      information.
2037
2038   :term:`ENABLE_BINARY_LOCALE_GENERATION`
2039      Variable that controls which locales for ``glibc`` are generated
2040      during the build (useful if the target device has 64Mbytes of RAM or
2041      less).
2042
2043   :term:`ERR_REPORT_DIR`
2044      When used with the :ref:`report-error <ref-classes-report-error>`
2045      class, specifies the path used for storing the debug files created by
2046      the :ref:`error reporting
2047      tool <dev-manual/common-tasks:using the error reporting tool>`, which
2048      allows you to submit build errors you encounter to a central
2049      database. By default, the value of this variable is
2050      ``${``\ :term:`LOG_DIR`\ ``}/error-report``.
2051
2052      You can set :term:`ERR_REPORT_DIR` to the path you want the error
2053      reporting tool to store the debug files as follows in your
2054      ``local.conf`` file::
2055
2056         ERR_REPORT_DIR = "path"
2057
2058   :term:`ERROR_QA`
2059      Specifies the quality assurance checks whose failures are reported as
2060      errors by the OpenEmbedded build system. You set this variable in
2061      your distribution configuration file. For a list of the checks you
2062      can control with this variable, see the
2063      ":ref:`insane.bbclass <ref-classes-insane>`" section.
2064
2065   :term:`EXCLUDE_FROM_SHLIBS`
2066      Triggers the OpenEmbedded build system's shared libraries resolver to
2067      exclude an entire package when scanning for shared libraries.
2068
2069      .. note::
2070
2071         The shared libraries resolver's functionality results in part from
2072         the internal function ``package_do_shlibs``, which is part of the
2073         :ref:`ref-tasks-package` task. You should be aware that the shared
2074         libraries resolver might implicitly define some dependencies between
2075         packages.
2076
2077      The :term:`EXCLUDE_FROM_SHLIBS` variable is similar to the
2078      :term:`PRIVATE_LIBS` variable, which excludes a
2079      package's particular libraries only and not the whole package.
2080
2081      Use the :term:`EXCLUDE_FROM_SHLIBS` variable by setting it to "1" for a
2082      particular package::
2083
2084         EXCLUDE_FROM_SHLIBS = "1"
2085
2086   :term:`EXCLUDE_FROM_WORLD`
2087      Directs BitBake to exclude a recipe from world builds (i.e.
2088      ``bitbake world``). During world builds, BitBake locates, parses and
2089      builds all recipes found in every layer exposed in the
2090      ``bblayers.conf`` configuration file.
2091
2092      To exclude a recipe from a world build using this variable, set the
2093      variable to "1" in the recipe.
2094
2095      .. note::
2096
2097         Recipes added to :term:`EXCLUDE_FROM_WORLD` may still be built during a
2098         world build in order to satisfy dependencies of other recipes. Adding
2099         a recipe to :term:`EXCLUDE_FROM_WORLD` only ensures that the recipe is not
2100         explicitly added to the list of build targets in a world build.
2101
2102   :term:`EXTENDPE`
2103      Used with file and pathnames to create a prefix for a recipe's
2104      version based on the recipe's :term:`PE` value. If :term:`PE`
2105      is set and greater than zero for a recipe, :term:`EXTENDPE` becomes that
2106      value (e.g if :term:`PE` is equal to "1" then :term:`EXTENDPE` becomes "1").
2107      If a recipe's :term:`PE` is not set (the default) or is equal to zero,
2108      :term:`EXTENDPE` becomes "".
2109
2110      See the :term:`STAMP` variable for an example.
2111
2112   :term:`EXTENDPKGV`
2113      The full package version specification as it appears on the final
2114      packages produced by a recipe. The variable's value is normally used
2115      to fix a runtime dependency to the exact same version of another
2116      package in the same recipe::
2117
2118         RDEPENDS:${PN}-additional-module = "${PN} (= ${EXTENDPKGV})"
2119
2120      The dependency relationships are intended to force the package
2121      manager to upgrade these types of packages in lock-step.
2122
2123   :term:`EXTERNAL_KERNEL_TOOLS`
2124      When set, the :term:`EXTERNAL_KERNEL_TOOLS` variable indicates that these
2125      tools are not in the source tree.
2126
2127      When kernel tools are available in the tree, they are preferred over
2128      any externally installed tools. Setting the :term:`EXTERNAL_KERNEL_TOOLS`
2129      variable tells the OpenEmbedded build system to prefer the installed
2130      external tools. See the
2131      :ref:`kernel-yocto <ref-classes-kernel-yocto>` class in
2132      ``meta/classes`` to see how the variable is used.
2133
2134   :term:`EXTERNALSRC`
2135      When inheriting the :ref:`externalsrc <ref-classes-externalsrc>`
2136      class, this variable points to the source tree, which is outside of
2137      the OpenEmbedded build system. When set, this variable sets the
2138      :term:`S` variable, which is what the OpenEmbedded build
2139      system uses to locate unpacked recipe source code.
2140
2141      For more information on ``externalsrc.bbclass``, see the
2142      ":ref:`externalsrc.bbclass <ref-classes-externalsrc>`" section. You
2143      can also find information on how to use this variable in the
2144      ":ref:`dev-manual/common-tasks:building software from an external source`"
2145      section in the Yocto Project Development Tasks Manual.
2146
2147   :term:`EXTERNALSRC_BUILD`
2148      When inheriting the :ref:`externalsrc <ref-classes-externalsrc>`
2149      class, this variable points to the directory in which the recipe's
2150      source code is built, which is outside of the OpenEmbedded build
2151      system. When set, this variable sets the :term:`B` variable,
2152      which is what the OpenEmbedded build system uses to locate the Build
2153      Directory.
2154
2155      For more information on ``externalsrc.bbclass``, see the
2156      ":ref:`externalsrc.bbclass <ref-classes-externalsrc>`" section. You
2157      can also find information on how to use this variable in the
2158      ":ref:`dev-manual/common-tasks:building software from an external source`"
2159      section in the Yocto Project Development Tasks Manual.
2160
2161   :term:`EXTRA_AUTORECONF`
2162      For recipes inheriting the :ref:`autotools <ref-classes-autotools>`
2163      class, you can use :term:`EXTRA_AUTORECONF` to specify extra options to
2164      pass to the ``autoreconf`` command that is executed during the
2165      :ref:`ref-tasks-configure` task.
2166
2167      The default value is "--exclude=autopoint".
2168
2169   :term:`EXTRA_IMAGE_FEATURES`
2170      A list of additional features to include in an image. When listing
2171      more than one feature, separate them with a space.
2172
2173      Typically, you configure this variable in your ``local.conf`` file,
2174      which is found in the :term:`Build Directory`.
2175      Although you can use this variable from within a recipe, best
2176      practices dictate that you do not.
2177
2178      .. note::
2179
2180         To enable primary features from within the image recipe, use the
2181         :term:`IMAGE_FEATURES` variable.
2182
2183      Here are some examples of features you can add:
2184
2185        - "dbg-pkgs" - Adds -dbg packages for all installed packages including
2186          symbol information for debugging and profiling.
2187
2188        - "debug-tweaks" - Makes an image suitable for debugging. For example, allows root logins without passwords and
2189          enables post-installation logging. See the 'allow-empty-password' and
2190          'post-install-logging' features in the ":ref:`ref-features-image`"
2191          section for more information.
2192        - "dev-pkgs" - Adds -dev packages for all installed packages. This is
2193          useful if you want to develop against the libraries in the image.
2194        - "read-only-rootfs" - Creates an image whose root filesystem is
2195          read-only. See the
2196          ":ref:`dev-manual/common-tasks:creating a read-only root filesystem`"
2197          section in the Yocto Project Development Tasks Manual for more
2198          information
2199        - "tools-debug" - Adds debugging tools such as gdb and strace.
2200        - "tools-sdk" - Adds development tools such as gcc, make,
2201          pkgconfig and so forth.
2202        - "tools-testapps" - Adds useful testing tools
2203          such as ts_print, aplay, arecord and so forth.
2204
2205      For a complete list of image features that ships with the Yocto
2206      Project, see the ":ref:`ref-features-image`" section.
2207
2208      For an example that shows how to customize your image by using this
2209      variable, see the ":ref:`dev-manual/common-tasks:customizing images using custom \`\`image_features\`\` and \`\`extra_image_features\`\``"
2210      section in the Yocto Project Development Tasks Manual.
2211
2212   :term:`EXTRA_IMAGECMD`
2213      Specifies additional options for the image creation command that has
2214      been specified in :term:`IMAGE_CMD`. When setting
2215      this variable, use an override for the associated image type. Here is
2216      an example::
2217
2218         EXTRA_IMAGECMD:ext3 ?= "-i 4096"
2219
2220   :term:`EXTRA_IMAGEDEPENDS`
2221      A list of recipes to build that do not provide packages for
2222      installing into the root filesystem.
2223
2224      Sometimes a recipe is required to build the final image but is not
2225      needed in the root filesystem. You can use the :term:`EXTRA_IMAGEDEPENDS`
2226      variable to list these recipes and thus specify the dependencies. A
2227      typical example is a required bootloader in a machine configuration.
2228
2229      .. note::
2230
2231         To add packages to the root filesystem, see the various
2232         :term:`RDEPENDS` and :term:`RRECOMMENDS` variables.
2233
2234   :term:`EXTRANATIVEPATH`
2235      A list of subdirectories of
2236      ``${``\ :term:`STAGING_BINDIR_NATIVE`\ ``}``
2237      added to the beginning of the environment variable ``PATH``. As an
2238      example, the following prepends
2239      "${STAGING_BINDIR_NATIVE}/foo:${STAGING_BINDIR_NATIVE}/bar:" to
2240      ``PATH``::
2241
2242         EXTRANATIVEPATH = "foo bar"
2243
2244   :term:`EXTRA_OECMAKE`
2245      Additional `CMake <https://cmake.org/overview/>`__ options. See the
2246      :ref:`cmake <ref-classes-cmake>` class for additional information.
2247
2248   :term:`EXTRA_OECONF`
2249      Additional ``configure`` script options. See
2250      :term:`PACKAGECONFIG_CONFARGS` for
2251      additional information on passing configure script options.
2252
2253   :term:`EXTRA_OEMAKE`
2254      Additional GNU ``make`` options.
2255
2256      Because the :term:`EXTRA_OEMAKE` defaults to "", you need to set the
2257      variable to specify any required GNU options.
2258
2259      :term:`PARALLEL_MAKE` and
2260      :term:`PARALLEL_MAKEINST` also make use of
2261      :term:`EXTRA_OEMAKE` to pass the required flags.
2262
2263   :term:`EXTRA_OESCONS`
2264      When inheriting the :ref:`scons <ref-classes-scons>` class, this
2265      variable specifies additional configuration options you want to pass
2266      to the ``scons`` command line.
2267
2268   :term:`EXTRA_USERS_PARAMS`
2269      When inheriting the :ref:`extrausers <ref-classes-extrausers>`
2270      class, this variable provides image level user and group operations.
2271      This is a more global method of providing user and group
2272      configuration as compared to using the
2273      :ref:`useradd <ref-classes-useradd>` class, which ties user and
2274      group configurations to a specific recipe.
2275
2276      The set list of commands you can configure using the
2277      :term:`EXTRA_USERS_PARAMS` is shown in the ``extrausers`` class. These
2278      commands map to the normal Unix commands of the same names::
2279
2280         # EXTRA_USERS_PARAMS = "\
2281         # useradd -p '' tester; \
2282         # groupadd developers; \
2283         # userdel nobody; \
2284         # groupdel -g video; \
2285         # groupmod -g 1020 developers; \
2286         # usermod -s /bin/sh tester; \
2287         # "
2288
2289      Additionally there is a special ``passwd-expire`` command that will
2290      cause the password for a user to be expired and thus force changing it
2291      on first login, for example::
2292
2293         EXTRA_USERS_PARAMS += " useradd myuser; passwd-expire myuser;"
2294
2295      .. note::
2296
2297         At present, ``passwd-expire`` may only work for remote logins when
2298         using OpenSSH and not dropbear as an SSH server.
2299
2300   :term:`FEATURE_PACKAGES`
2301      Defines one or more packages to include in an image when a specific
2302      item is included in :term:`IMAGE_FEATURES`.
2303      When setting the value, :term:`FEATURE_PACKAGES` should have the name of
2304      the feature item as an override. Here is an example::
2305
2306         FEATURE_PACKAGES_widget = "package1 package2"
2307
2308      In this example, if "widget" were added to :term:`IMAGE_FEATURES`,
2309      package1 and package2 would be included in the image.
2310
2311      .. note::
2312
2313         Packages installed by features defined through :term:`FEATURE_PACKAGES`
2314         are often package groups. While similarly named, you should not
2315         confuse the :term:`FEATURE_PACKAGES` variable with package groups, which
2316         are discussed elsewhere in the documentation.
2317
2318   :term:`FEED_DEPLOYDIR_BASE_URI`
2319      Points to the base URL of the server and location within the
2320      document-root that provides the metadata and packages required by
2321      OPKG to support runtime package management of IPK packages. You set
2322      this variable in your ``local.conf`` file.
2323
2324      Consider the following example::
2325
2326         FEED_DEPLOYDIR_BASE_URI = "http://192.168.7.1/BOARD-dir"
2327
2328      This example assumes you are serving
2329      your packages over HTTP and your databases are located in a directory
2330      named ``BOARD-dir``, which is underneath your HTTP server's
2331      document-root. In this case, the OpenEmbedded build system generates
2332      a set of configuration files for you in your target that work with
2333      the feed.
2334
2335   :term:`FILES`
2336      The list of files and directories that are placed in a package. The
2337      :term:`PACKAGES` variable lists the packages
2338      generated by a recipe.
2339
2340      To use the :term:`FILES` variable, provide a package name override that
2341      identifies the resulting package. Then, provide a space-separated
2342      list of files or paths that identify the files you want included as
2343      part of the resulting package. Here is an example::
2344
2345         FILES:${PN} += "${bindir}/mydir1 ${bindir}/mydir2/myfile"
2346
2347      .. note::
2348
2349         -  When specifying files or paths, you can pattern match using
2350            Python's
2351            `glob <https://docs.python.org/3/library/glob.html>`_
2352            syntax. For details on the syntax, see the documentation by
2353            following the previous link.
2354
2355         -  When specifying paths as part of the :term:`FILES` variable, it is
2356            good practice to use appropriate path variables. For example,
2357            use ``${sysconfdir}`` rather than ``/etc``, or ``${bindir}``
2358            rather than ``/usr/bin``. You can find a list of these
2359            variables at the top of the ``meta/conf/bitbake.conf`` file in
2360            the :term:`Source Directory`. You will also
2361            find the default values of the various ``FILES:*`` variables in
2362            this file.
2363
2364      If some of the files you provide with the :term:`FILES` variable are
2365      editable and you know they should not be overwritten during the
2366      package update process by the Package Management System (PMS), you
2367      can identify these files so that the PMS will not overwrite them. See
2368      the :term:`CONFFILES` variable for information on
2369      how to identify these files to the PMS.
2370
2371   :term:`FILES_SOLIBSDEV`
2372      Defines the file specification to match
2373      :term:`SOLIBSDEV`. In other words,
2374      :term:`FILES_SOLIBSDEV` defines the full path name of the development
2375      symbolic link (symlink) for shared libraries on the target platform.
2376
2377      The following statement from the ``bitbake.conf`` shows how it is
2378      set::
2379
2380         FILES_SOLIBSDEV ?= "${base_libdir}/lib*${SOLIBSDEV} ${libdir}/lib*${SOLIBSDEV}"
2381
2382   :term:`FILESEXTRAPATHS`
2383      Extends the search path the OpenEmbedded build system uses when
2384      looking for files and patches as it processes recipes and append
2385      files. The default directories BitBake uses when it processes recipes
2386      are initially defined by the :term:`FILESPATH`
2387      variable. You can extend :term:`FILESPATH` variable by using
2388      :term:`FILESEXTRAPATHS`.
2389
2390      Best practices dictate that you accomplish this by using
2391      :term:`FILESEXTRAPATHS` from within a ``.bbappend`` file and that you
2392      prepend paths as follows::
2393
2394         FILESEXTRAPATHS:prepend := "${THISDIR}/${PN}:"
2395
2396      In the above example, the build system first
2397      looks for files in a directory that has the same name as the
2398      corresponding append file.
2399
2400      .. note::
2401
2402         When extending :term:`FILESEXTRAPATHS`, be sure to use the immediate
2403         expansion (``:=``) operator. Immediate expansion makes sure that
2404         BitBake evaluates :term:`THISDIR` at the time the
2405         directive is encountered rather than at some later time when
2406         expansion might result in a directory that does not contain the
2407         files you need.
2408
2409         Also, include the trailing separating colon character if you are
2410         prepending. The trailing colon character is necessary because you
2411         are directing BitBake to extend the path by prepending directories
2412         to the search path.
2413
2414      Here is another common use::
2415
2416         FILESEXTRAPATHS:prepend := "${THISDIR}/files:"
2417
2418      In this example, the build system extends the
2419      :term:`FILESPATH` variable to include a directory named ``files`` that is
2420      in the same directory as the corresponding append file.
2421
2422      This next example specifically adds three paths::
2423
2424         FILESEXTRAPATHS:prepend := "path_1:path_2:path_3:"
2425
2426      A final example shows how you can extend the search path and include
2427      a :term:`MACHINE`-specific override, which is useful
2428      in a BSP layer::
2429
2430          FILESEXTRAPATHS:prepend:intel-x86-common := "${THISDIR}/${PN}:"
2431
2432      The previous statement appears in the
2433      ``linux-yocto-dev.bbappend`` file, which is found in the
2434      :ref:`overview-manual/development-environment:yocto project source repositories` in
2435      ``meta-intel/common/recipes-kernel/linux``. Here, the machine
2436      override is a special :term:`PACKAGE_ARCH`
2437      definition for multiple ``meta-intel`` machines.
2438
2439      .. note::
2440
2441         For a layer that supports a single BSP, the override could just be
2442         the value of :term:`MACHINE`.
2443
2444      By prepending paths in ``.bbappend`` files, you allow multiple append
2445      files that reside in different layers but are used for the same
2446      recipe to correctly extend the path.
2447
2448   :term:`FILESOVERRIDES`
2449      A subset of :term:`OVERRIDES` used by the
2450      OpenEmbedded build system for creating
2451      :term:`FILESPATH`. The :term:`FILESOVERRIDES` variable
2452      uses overrides to automatically extend the
2453      :term:`FILESPATH` variable. For an example of how
2454      that works, see the :term:`FILESPATH` variable
2455      description. Additionally, you find more information on how overrides
2456      are handled in the
2457      ":ref:`bitbake:bitbake-user-manual/bitbake-user-manual-metadata:conditional syntax (overrides)`"
2458      section of the BitBake User Manual.
2459
2460      By default, the :term:`FILESOVERRIDES` variable is defined as::
2461
2462         FILESOVERRIDES = "${TRANSLATED_TARGET_ARCH}:${MACHINEOVERRIDES}:${DISTROOVERRIDES}"
2463
2464      .. note::
2465
2466         Do not hand-edit the :term:`FILESOVERRIDES` variable. The values match up
2467         with expected overrides and are used in an expected manner by the
2468         build system.
2469
2470   :term:`FILESPATH`
2471      The default set of directories the OpenEmbedded build system uses
2472      when searching for patches and files.
2473
2474      During the build process, BitBake searches each directory in
2475      :term:`FILESPATH` in the specified order when looking for files and
2476      patches specified by each ``file://`` URI in a recipe's
2477      :term:`SRC_URI` statements.
2478
2479      The default value for the :term:`FILESPATH` variable is defined in the
2480      ``base.bbclass`` class found in ``meta/classes`` in the
2481      :term:`Source Directory`::
2482
2483         FILESPATH = "${@base_set_filespath(["${FILE_DIRNAME}/${BP}", \
2484             "${FILE_DIRNAME}/${BPN}", "${FILE_DIRNAME}/files"], d)}"
2485
2486      The
2487      :term:`FILESPATH` variable is automatically extended using the overrides
2488      from the :term:`FILESOVERRIDES` variable.
2489
2490      .. note::
2491
2492         -  Do not hand-edit the :term:`FILESPATH` variable. If you want the
2493            build system to look in directories other than the defaults,
2494            extend the :term:`FILESPATH` variable by using the
2495            :term:`FILESEXTRAPATHS` variable.
2496
2497         -  Be aware that the default :term:`FILESPATH` directories do not map
2498            to directories in custom layers where append files
2499            (``.bbappend``) are used. If you want the build system to find
2500            patches or files that reside with your append files, you need
2501            to extend the :term:`FILESPATH` variable by using the
2502            :term:`FILESEXTRAPATHS` variable.
2503
2504      You can take advantage of this searching behavior in useful ways. For
2505      example, consider a case where there is the following directory structure
2506      for general and machine-specific configurations::
2507
2508         files/defconfig
2509         files/MACHINEA/defconfig
2510         files/MACHINEB/defconfig
2511
2512      Also in the example, the :term:`SRC_URI` statement contains
2513      "file://defconfig". Given this scenario, you can set
2514      :term:`MACHINE` to "MACHINEA" and cause the build
2515      system to use files from ``files/MACHINEA``. Set :term:`MACHINE` to
2516      "MACHINEB" and the build system uses files from ``files/MACHINEB``.
2517      Finally, for any machine other than "MACHINEA" and "MACHINEB", the
2518      build system uses files from ``files/defconfig``.
2519
2520      You can find out more about the patching process in the
2521      ":ref:`overview-manual/concepts:patching`" section
2522      in the Yocto Project Overview and Concepts Manual and the
2523      ":ref:`dev-manual/common-tasks:patching code`" section in
2524      the Yocto Project Development Tasks Manual. See the
2525      :ref:`ref-tasks-patch` task as well.
2526
2527   :term:`FILESYSTEM_PERMS_TABLES`
2528      Allows you to define your own file permissions settings table as part
2529      of your configuration for the packaging process. For example, suppose
2530      you need a consistent set of custom permissions for a set of groups
2531      and users across an entire work project. It is best to do this in the
2532      packages themselves but this is not always possible.
2533
2534      By default, the OpenEmbedded build system uses the ``fs-perms.txt``,
2535      which is located in the ``meta/files`` folder in the :term:`Source Directory`.
2536      If you create your own file
2537      permissions setting table, you should place it in your layer or the
2538      distro's layer.
2539
2540      You define the :term:`FILESYSTEM_PERMS_TABLES` variable in the
2541      ``conf/local.conf`` file, which is found in the :term:`Build Directory`,
2542      to point to your custom
2543      ``fs-perms.txt``. You can specify more than a single file permissions
2544      setting table. The paths you specify to these files must be defined
2545      within the :term:`BBPATH` variable.
2546
2547      For guidance on how to create your own file permissions settings
2548      table file, examine the existing ``fs-perms.txt``.
2549
2550   :term:`FIT_DESC`
2551      Specifies the description string encoded into a fitImage. The default
2552      value is set by the :ref:`kernel-fitimage <ref-classes-kernel-fitimage>`
2553      class as follows::
2554
2555         FIT_DESC ?= "U-Boot fitImage for ${DISTRO_NAME}/${PV}/${MACHINE}"
2556
2557   :term:`FIT_GENERATE_KEYS`
2558      Decides whether to generate the keys for signing fitImage if they
2559      don't already exist. The keys are created in :term:`UBOOT_SIGN_KEYDIR`.
2560      The default value is 0.
2561
2562   :term:`FIT_HASH_ALG`
2563      Specifies the hash algorithm used in creating the FIT Image. For e.g. sha256.
2564
2565   :term:`FIT_KERNEL_COMP_ALG`
2566      Compression algorithm to use for the kernel image inside the FIT Image.
2567      At present, the only supported values are "gzip" (default) or "none"
2568      If you set this variable to anything other than "none" you may also need
2569      to set :term:`FIT_KERNEL_COMP_ALG_EXTENSION`.
2570
2571   :term:`FIT_KERNEL_COMP_ALG_EXTENSION`
2572      File extension corresponding to :term:`FIT_KERNEL_COMP_ALG`. The default
2573      value is ".gz".
2574
2575   :term:`FIT_KEY_GENRSA_ARGS`
2576      Arguments to openssl genrsa for generating RSA private key for signing
2577      fitImage. The default value is "-F4". i.e. the public exponent 65537 to
2578      use.
2579
2580   :term:`FIT_KEY_REQ_ARGS`
2581      Arguments to openssl req for generating certificate for signing fitImage.
2582      The default value is "-batch -new". batch for non interactive mode
2583      and new for generating new keys.
2584
2585   :term:`FIT_KEY_SIGN_PKCS`
2586      Format for public key certificate used in signing fitImage.
2587      The default value is "x509".
2588
2589   :term:`FIT_SIGN_ALG`
2590      Specifies the signature algorithm used in creating the FIT Image.
2591      For e.g. rsa2048.
2592
2593   :term:`FIT_SIGN_NUMBITS`
2594      Size of private key in number of bits used in fitImage. The default
2595      value is "2048".
2596
2597   :term:`FIT_SIGN_INDIVIDUAL`
2598      If set to "1", then the :ref:`kernel-fitimage <ref-classes-kernel-fitimage>`
2599      class will sign the kernel, dtb and ramdisk images individually in addition
2600      to signing the fitImage itself. This could be useful if you are
2601      intending to verify signatures in another context than booting via
2602      U-Boot.
2603
2604   :term:`FONT_EXTRA_RDEPENDS`
2605      When inheriting the :ref:`fontcache <ref-classes-fontcache>` class,
2606      this variable specifies the runtime dependencies for font packages.
2607      By default, the :term:`FONT_EXTRA_RDEPENDS` is set to "fontconfig-utils".
2608
2609   :term:`FONT_PACKAGES`
2610      When inheriting the :ref:`fontcache <ref-classes-fontcache>` class,
2611      this variable identifies packages containing font files that need to
2612      be cached by Fontconfig. By default, the ``fontcache`` class assumes
2613      that fonts are in the recipe's main package (i.e.
2614      ``${``\ :term:`PN`\ ``}``). Use this variable if fonts you
2615      need are in a package other than that main package.
2616
2617   :term:`FORCE_RO_REMOVE`
2618      Forces the removal of the packages listed in ``ROOTFS_RO_UNNEEDED``
2619      during the generation of the root filesystem.
2620
2621      Set the variable to "1" to force the removal of these packages.
2622
2623   :term:`FULL_OPTIMIZATION`
2624      The options to pass in :term:`TARGET_CFLAGS` and :term:`CFLAGS` when
2625      compiling an optimized system. This variable defaults to "-O2 -pipe
2626      ${DEBUG_FLAGS}".
2627
2628   :term:`GCCPIE`
2629      Enables Position Independent Executables (PIE) within the GNU C
2630      Compiler (GCC). Enabling PIE in the GCC makes Return Oriented
2631      Programming (ROP) attacks much more difficult to execute.
2632
2633      By default the ``security_flags.inc`` file enables PIE by setting the
2634      variable as follows::
2635
2636         GCCPIE ?= "--enable-default-pie"
2637
2638   :term:`GCCVERSION`
2639      Specifies the default version of the GNU C Compiler (GCC) used for
2640      compilation. By default, :term:`GCCVERSION` is set to "8.x" in the
2641      ``meta/conf/distro/include/tcmode-default.inc`` include file::
2642
2643         GCCVERSION ?= "8.%"
2644
2645      You can override this value by setting it in a
2646      configuration file such as the ``local.conf``.
2647
2648   :term:`GDB`
2649      The minimal command and arguments to run the GNU Debugger.
2650
2651   :term:`GITDIR`
2652      The directory in which a local copy of a Git repository is stored
2653      when it is cloned.
2654
2655   :term:`GLIBC_GENERATE_LOCALES`
2656      Specifies the list of GLIBC locales to generate should you not wish
2657      to generate all LIBC locals, which can be time consuming.
2658
2659      .. note::
2660
2661         If you specifically remove the locale ``en_US.UTF-8``, you must set
2662         :term:`IMAGE_LINGUAS` appropriately.
2663
2664      You can set :term:`GLIBC_GENERATE_LOCALES` in your ``local.conf`` file.
2665      By default, all locales are generated.
2666      ::
2667
2668         GLIBC_GENERATE_LOCALES = "en_GB.UTF-8 en_US.UTF-8"
2669
2670   :term:`GROUPADD_PARAM`
2671      When inheriting the :ref:`useradd <ref-classes-useradd>` class,
2672      this variable specifies for a package what parameters should be
2673      passed to the ``groupadd`` command if you wish to add a group to the
2674      system when the package is installed.
2675
2676      Here is an example from the ``dbus`` recipe::
2677
2678         GROUPADD_PARAM:${PN} = "-r netdev"
2679
2680      For information on the standard Linux shell command
2681      ``groupadd``, see https://linux.die.net/man/8/groupadd.
2682
2683   :term:`GROUPMEMS_PARAM`
2684      When inheriting the :ref:`useradd <ref-classes-useradd>` class,
2685      this variable specifies for a package what parameters should be
2686      passed to the ``groupmems`` command if you wish to modify the members
2687      of a group when the package is installed.
2688
2689      For information on the standard Linux shell command ``groupmems``,
2690      see https://linux.die.net/man/8/groupmems.
2691
2692   :term:`GRUB_GFXSERIAL`
2693      Configures the GNU GRand Unified Bootloader (GRUB) to have graphics
2694      and serial in the boot menu. Set this variable to "1" in your
2695      ``local.conf`` or distribution configuration file to enable graphics
2696      and serial in the menu.
2697
2698      See the :ref:`grub-efi <ref-classes-grub-efi>` class for more
2699      information on how this variable is used.
2700
2701   :term:`GRUB_OPTS`
2702      Additional options to add to the GNU GRand Unified Bootloader (GRUB)
2703      configuration. Use a semi-colon character (``;``) to separate
2704      multiple options.
2705
2706      The :term:`GRUB_OPTS` variable is optional. See the
2707      :ref:`grub-efi <ref-classes-grub-efi>` class for more information
2708      on how this variable is used.
2709
2710   :term:`GRUB_TIMEOUT`
2711      Specifies the timeout before executing the default ``LABEL`` in the
2712      GNU GRand Unified Bootloader (GRUB).
2713
2714      The :term:`GRUB_TIMEOUT` variable is optional. See the
2715      :ref:`grub-efi <ref-classes-grub-efi>` class for more information
2716      on how this variable is used.
2717
2718   :term:`GTKIMMODULES_PACKAGES`
2719      When inheriting the
2720      :ref:`gtk-immodules-cache <ref-classes-gtk-immodules-cache>` class,
2721      this variable specifies the packages that contain the GTK+ input
2722      method modules being installed when the modules are in packages other
2723      than the main package.
2724
2725   :term:`HOMEPAGE`
2726      Website where more information about the software the recipe is
2727      building can be found.
2728
2729   :term:`HOST_ARCH`
2730      The name of the target architecture, which is normally the same as
2731      :term:`TARGET_ARCH`. The OpenEmbedded build system
2732      supports many architectures. Here is an example list of architectures
2733      supported. This list is by no means complete as the architecture is
2734      configurable:
2735
2736      - arm
2737      - i586
2738      - x86_64
2739      - powerpc
2740      - powerpc64
2741      - mips
2742      - mipsel
2743
2744   :term:`HOST_CC_ARCH`
2745      Specifies architecture-specific compiler flags that are passed to the
2746      C compiler.
2747
2748      Default initialization for :term:`HOST_CC_ARCH` varies depending on what
2749      is being built:
2750
2751      -  :term:`TARGET_CC_ARCH` when building for the
2752         target
2753
2754      -  :term:`BUILD_CC_ARCH` when building for the build host (i.e.
2755         ``-native``)
2756
2757      -  ``BUILDSDK_CC_ARCH`` when building for an SDK (i.e.
2758         ``nativesdk-``)
2759
2760   :term:`HOST_OS`
2761      Specifies the name of the target operating system, which is normally
2762      the same as the :term:`TARGET_OS`. The variable can
2763      be set to "linux" for ``glibc``-based systems and to "linux-musl" for
2764      ``musl``. For ARM/EABI targets, there are also "linux-gnueabi" and
2765      "linux-musleabi" values possible.
2766
2767   :term:`HOST_PREFIX`
2768      Specifies the prefix for the cross-compile toolchain. :term:`HOST_PREFIX`
2769      is normally the same as :term:`TARGET_PREFIX`.
2770
2771   :term:`HOST_SYS`
2772      Specifies the system, including the architecture and the operating
2773      system, for which the build is occurring in the context of the
2774      current recipe.
2775
2776      The OpenEmbedded build system automatically sets this variable based
2777      on :term:`HOST_ARCH`,
2778      :term:`HOST_VENDOR`, and
2779      :term:`HOST_OS` variables.
2780
2781      .. note::
2782
2783         You do not need to set the variable yourself.
2784
2785      Consider these two examples:
2786
2787      -  Given a native recipe on a 32-bit x86 machine running Linux, the
2788         value is "i686-linux".
2789
2790      -  Given a recipe being built for a little-endian MIPS target running
2791         Linux, the value might be "mipsel-linux".
2792
2793   :term:`HOSTTOOLS`
2794      A space-separated list (filter) of tools on the build host that
2795      should be allowed to be called from within build tasks. Using this
2796      filter helps reduce the possibility of host contamination. If a tool
2797      specified in the value of :term:`HOSTTOOLS` is not found on the build
2798      host, the OpenEmbedded build system produces an error and the build
2799      is not started.
2800
2801      For additional information, see
2802      :term:`HOSTTOOLS_NONFATAL`.
2803
2804   :term:`HOSTTOOLS_NONFATAL`
2805      A space-separated list (filter) of tools on the build host that
2806      should be allowed to be called from within build tasks. Using this
2807      filter helps reduce the possibility of host contamination. Unlike
2808      :term:`HOSTTOOLS`, the OpenEmbedded build system
2809      does not produce an error if a tool specified in the value of
2810      :term:`HOSTTOOLS_NONFATAL` is not found on the build host. Thus, you can
2811      use :term:`HOSTTOOLS_NONFATAL` to filter optional host tools.
2812
2813   :term:`HOST_VENDOR`
2814      Specifies the name of the vendor. :term:`HOST_VENDOR` is normally the
2815      same as :term:`TARGET_VENDOR`.
2816
2817   :term:`ICECC_DISABLED`
2818      Disables or enables the ``icecc`` (Icecream) function. For more
2819      information on this function and best practices for using this
2820      variable, see the ":ref:`icecc.bbclass <ref-classes-icecc>`"
2821      section.
2822
2823      Setting this variable to "1" in your ``local.conf`` disables the
2824      function::
2825
2826         ICECC_DISABLED ??= "1"
2827
2828      To enable the function, set the variable as follows::
2829
2830         ICECC_DISABLED = ""
2831
2832   :term:`ICECC_ENV_EXEC`
2833      Points to the ``icecc-create-env`` script that you provide. This
2834      variable is used by the :ref:`icecc <ref-classes-icecc>` class. You
2835      set this variable in your ``local.conf`` file.
2836
2837      If you do not point to a script that you provide, the OpenEmbedded
2838      build system uses the default script provided by the
2839      ``icecc-create-env.bb`` recipe, which is a modified version and not
2840      the one that comes with ``icecc``.
2841
2842   :term:`ICECC_PARALLEL_MAKE`
2843      Extra options passed to the ``make`` command during the
2844      :ref:`ref-tasks-compile` task that specify parallel
2845      compilation. This variable usually takes the form of "-j x", where x
2846      represents the maximum number of parallel threads ``make`` can run.
2847
2848      .. note::
2849
2850         The options passed affect builds on all enabled machines on the
2851         network, which are machines running the ``iceccd`` daemon.
2852
2853      If your enabled machines support multiple cores, coming up with the
2854      maximum number of parallel threads that gives you the best
2855      performance could take some experimentation since machine speed,
2856      network lag, available memory, and existing machine loads can all
2857      affect build time. Consequently, unlike the
2858      :term:`PARALLEL_MAKE` variable, there is no
2859      rule-of-thumb for setting :term:`ICECC_PARALLEL_MAKE` to achieve optimal
2860      performance.
2861
2862      If you do not set :term:`ICECC_PARALLEL_MAKE`, the build system does not
2863      use it (i.e. the system does not detect and assign the number of
2864      cores as is done with :term:`PARALLEL_MAKE`).
2865
2866   :term:`ICECC_PATH`
2867      The location of the ``icecc`` binary. You can set this variable in
2868      your ``local.conf`` file. If your ``local.conf`` file does not define
2869      this variable, the :ref:`icecc <ref-classes-icecc>` class attempts
2870      to define it by locating ``icecc`` using ``which``.
2871
2872   :term:`ICECC_USER_CLASS_BL`
2873      Identifies user classes that you do not want the Icecream distributed
2874      compile support to consider. This variable is used by the
2875      :ref:`icecc <ref-classes-icecc>` class. You set this variable in
2876      your ``local.conf`` file.
2877
2878      When you list classes using this variable, you are "blacklisting"
2879      them from distributed compilation across remote hosts. Any classes
2880      you list will be distributed and compiled locally.
2881
2882   :term:`ICECC_USER_PACKAGE_BL`
2883      Identifies user recipes that you do not want the Icecream distributed
2884      compile support to consider. This variable is used by the
2885      :ref:`icecc <ref-classes-icecc>` class. You set this variable in
2886      your ``local.conf`` file.
2887
2888      When you list packages using this variable, you are "blacklisting"
2889      them from distributed compilation across remote hosts. Any packages
2890      you list will be distributed and compiled locally.
2891
2892   :term:`ICECC_USER_PACKAGE_WL`
2893      Identifies user recipes that use an empty
2894      :term:`PARALLEL_MAKE` variable that you want to
2895      force remote distributed compilation on using the Icecream
2896      distributed compile support. This variable is used by the
2897      :ref:`icecc <ref-classes-icecc>` class. You set this variable in
2898      your ``local.conf`` file.
2899
2900   :term:`IMAGE_BASENAME`
2901      The base name of image output files. This variable defaults to the
2902      recipe name (``${``\ :term:`PN`\ ``}``).
2903
2904   :term:`IMAGE_EFI_BOOT_FILES`
2905      A space-separated list of files installed into the boot partition
2906      when preparing an image using the Wic tool with the
2907      ``bootimg-efi`` source plugin. By default,
2908      the files are
2909      installed under the same name as the source files. To change the
2910      installed name, separate it from the original name with a semi-colon
2911      (;). Source files need to be located in
2912      :term:`DEPLOY_DIR_IMAGE`. Here are two
2913      examples::
2914
2915         IMAGE_EFI_BOOT_FILES = "${KERNEL_IMAGETYPE};bz2"
2916         IMAGE_EFI_BOOT_FILES = "${KERNEL_IMAGETYPE} microcode.cpio"
2917
2918      Alternatively, source files can be picked up using a glob pattern. In
2919      this case, the destination file must have the same name as the base
2920      name of the source file path. To install files into a directory
2921      within the target location, pass its name after a semi-colon (;).
2922      Here are two examples::
2923
2924         IMAGE_EFI_BOOT_FILES = "boot/loader/*"
2925         IMAGE_EFI_BOOT_FILES = "boot/loader/*;boot/"
2926
2927      The first example
2928      installs all files from ``${DEPLOY_DIR_IMAGE}/boot/loader/``
2929      into the root of the target partition. The second example installs
2930      the same files into a ``boot`` directory within the target partition.
2931
2932      You can find information on how to use the Wic tool in the
2933      ":ref:`dev-manual/common-tasks:creating partitioned images using wic`"
2934      section of the Yocto Project Development Tasks Manual. Reference
2935      material for Wic is located in the
2936      ":doc:`/ref-manual/kickstart`" chapter.
2937
2938   :term:`IMAGE_BOOT_FILES`
2939      A space-separated list of files installed into the boot partition
2940      when preparing an image using the Wic tool with the
2941      ``bootimg-partition`` source plugin. By default,
2942      the files are
2943      installed under the same name as the source files. To change the
2944      installed name, separate it from the original name with a semi-colon
2945      (;). Source files need to be located in
2946      :term:`DEPLOY_DIR_IMAGE`. Here are two
2947      examples::
2948
2949         IMAGE_BOOT_FILES = "u-boot.img uImage;kernel"
2950         IMAGE_BOOT_FILES = "u-boot.${UBOOT_SUFFIX} ${KERNEL_IMAGETYPE}"
2951
2952      Alternatively, source files can be picked up using a glob pattern. In
2953      this case, the destination file must have the same name as the base
2954      name of the source file path. To install files into a directory
2955      within the target location, pass its name after a semi-colon (;).
2956      Here are two examples::
2957
2958         IMAGE_BOOT_FILES = "bcm2835-bootfiles/*"
2959         IMAGE_BOOT_FILES = "bcm2835-bootfiles/*;boot/"
2960
2961      The first example
2962      installs all files from ``${DEPLOY_DIR_IMAGE}/bcm2835-bootfiles``
2963      into the root of the target partition. The second example installs
2964      the same files into a ``boot`` directory within the target partition.
2965
2966      You can find information on how to use the Wic tool in the
2967      ":ref:`dev-manual/common-tasks:creating partitioned images using wic`"
2968      section of the Yocto Project Development Tasks Manual. Reference
2969      material for Wic is located in the
2970      ":doc:`/ref-manual/kickstart`" chapter.
2971
2972   :term:`IMAGE_CLASSES`
2973      A list of classes that all images should inherit. You typically use
2974      this variable to specify the list of classes that register the
2975      different types of images the OpenEmbedded build system creates.
2976
2977      The default value for :term:`IMAGE_CLASSES` is ``image_types``. You can
2978      set this variable in your ``local.conf`` or in a distribution
2979      configuration file.
2980
2981      For more information, see ``meta/classes/image_types.bbclass`` in the
2982      :term:`Source Directory`.
2983
2984   :term:`IMAGE_CMD`
2985      Specifies the command to create the image file for a specific image
2986      type, which corresponds to the value set in
2987      :term:`IMAGE_FSTYPES`, (e.g. ``ext3``,
2988      ``btrfs``, and so forth). When setting this variable, you should use
2989      an override for the associated type. Here is an example::
2990
2991         IMAGE_CMD:jffs2 = "mkfs.jffs2 --root=${IMAGE_ROOTFS} --faketime \
2992             --output=${IMGDEPLOYDIR}/${IMAGE_NAME}${IMAGE_NAME_SUFFIX}.jffs2 \
2993             ${EXTRA_IMAGECMD}"
2994
2995      You typically do not need to set this variable unless you are adding
2996      support for a new image type. For more examples on how to set this
2997      variable, see the :ref:`image_types <ref-classes-image_types>`
2998      class file, which is ``meta/classes/image_types.bbclass``.
2999
3000   :term:`IMAGE_DEVICE_TABLES`
3001      Specifies one or more files that contain custom device tables that
3002      are passed to the ``makedevs`` command as part of creating an image.
3003      These files list basic device nodes that should be created under
3004      ``/dev`` within the image. If :term:`IMAGE_DEVICE_TABLES` is not set,
3005      ``files/device_table-minimal.txt`` is used, which is located by
3006      :term:`BBPATH`. For details on how you should write
3007      device table files, see ``meta/files/device_table-minimal.txt`` as an
3008      example.
3009
3010   :term:`IMAGE_FEATURES`
3011      The primary list of features to include in an image. Typically, you
3012      configure this variable in an image recipe. Although you can use this
3013      variable from your ``local.conf`` file, which is found in the
3014      :term:`Build Directory`, best practices dictate that you do
3015      not.
3016
3017      .. note::
3018
3019         To enable extra features from outside the image recipe, use the
3020         :term:`EXTRA_IMAGE_FEATURES` variable.
3021
3022      For a list of image features that ships with the Yocto Project, see
3023      the ":ref:`ref-features-image`" section.
3024
3025      For an example that shows how to customize your image by using this
3026      variable, see the ":ref:`dev-manual/common-tasks:customizing images using custom \`\`image_features\`\` and \`\`extra_image_features\`\``"
3027      section in the Yocto Project Development Tasks Manual.
3028
3029   :term:`IMAGE_FSTYPES`
3030      Specifies the formats the OpenEmbedded build system uses during the
3031      build when creating the root filesystem. For example, setting
3032      :term:`IMAGE_FSTYPES` as follows causes the build system to create root
3033      filesystems using two formats: ``.ext3`` and ``.tar.bz2``::
3034
3035         IMAGE_FSTYPES = "ext3 tar.bz2"
3036
3037      For the complete list of supported image formats from which you can
3038      choose, see :term:`IMAGE_TYPES`.
3039
3040      .. note::
3041
3042         -  If an image recipe uses the "inherit image" line and you are
3043            setting :term:`IMAGE_FSTYPES` inside the recipe, you must set
3044            :term:`IMAGE_FSTYPES` prior to using the "inherit image" line.
3045
3046         -  Due to the way the OpenEmbedded build system processes this
3047            variable, you cannot update its contents by using ``:append``
3048            or ``:prepend``. You must use the ``+=`` operator to add one or
3049            more options to the :term:`IMAGE_FSTYPES` variable.
3050
3051   :term:`IMAGE_INSTALL`
3052      Used by recipes to specify the packages to install into an image
3053      through the :ref:`image <ref-classes-image>` class. Use the
3054      :term:`IMAGE_INSTALL` variable with care to avoid ordering issues.
3055
3056      Image recipes set :term:`IMAGE_INSTALL` to specify the packages to
3057      install into an image through ``image.bbclass``. Additionally,
3058      there are "helper" classes such as the
3059      :ref:`core-image <ref-classes-core-image>` class which can
3060      take lists used with :term:`IMAGE_FEATURES` and turn them into
3061      auto-generated entries in :term:`IMAGE_INSTALL` in addition to its
3062      default contents.
3063
3064      When you use this variable, it is best to use it as follows::
3065
3066         IMAGE_INSTALL:append = " package-name"
3067
3068      Be sure to include the space
3069      between the quotation character and the start of the package name or
3070      names.
3071
3072      .. note::
3073
3074         -  When working with a
3075            :ref:`core-image-minimal-initramfs <ref-manual/images:images>`
3076            image, do not use the :term:`IMAGE_INSTALL` variable to specify
3077            packages for installation. Instead, use the
3078            :term:`PACKAGE_INSTALL` variable, which
3079            allows the initial RAM filesystem (initramfs) recipe to use a
3080            fixed set of packages and not be affected by :term:`IMAGE_INSTALL`.
3081            For information on creating an initramfs, see the
3082            ":ref:`dev-manual/common-tasks:building an initial ram filesystem (initramfs) image`"
3083            section in the Yocto Project Development Tasks Manual.
3084
3085         -  Using :term:`IMAGE_INSTALL` with the
3086            :ref:`+= <bitbake:bitbake-user-manual/bitbake-user-manual-metadata:appending (+=) and prepending (=+) with spaces>`
3087            BitBake operator within the ``/conf/local.conf`` file or from
3088            within an image recipe is not recommended. Use of this operator
3089            in these ways can cause ordering issues. Since
3090            ``core-image.bbclass`` sets :term:`IMAGE_INSTALL` to a default
3091            value using the
3092            :ref:`?= <bitbake:bitbake-user-manual/bitbake-user-manual-metadata:setting a default value (?=)>`
3093            operator, using a ``+=`` operation against :term:`IMAGE_INSTALL`
3094            results in unexpected behavior when used within
3095            ``conf/local.conf``. Furthermore, the same operation from
3096            within an image recipe may or may not succeed depending on the
3097            specific situation. In both these cases, the behavior is
3098            contrary to how most users expect the ``+=`` operator to work.
3099
3100   :term:`IMAGE_LINGUAS`
3101      Specifies the list of locales to install into the image during the
3102      root filesystem construction process. The OpenEmbedded build system
3103      automatically splits locale files, which are used for localization,
3104      into separate packages. Setting the :term:`IMAGE_LINGUAS` variable
3105      ensures that any locale packages that correspond to packages already
3106      selected for installation into the image are also installed. Here is
3107      an example::
3108
3109         IMAGE_LINGUAS = "pt-br de-de"
3110
3111      In this example, the build system ensures any Brazilian Portuguese
3112      and German locale files that correspond to packages in the image are
3113      installed (i.e. ``*-locale-pt-br`` and ``*-locale-de-de`` as well as
3114      ``*-locale-pt`` and ``*-locale-de``, since some software packages
3115      only provide locale files by language and not by country-specific
3116      language).
3117
3118      See the :term:`GLIBC_GENERATE_LOCALES`
3119      variable for information on generating GLIBC locales.
3120
3121
3122   :term:`IMAGE_LINK_NAME`
3123      The name of the output image symlink (which does not include
3124      the version part as :term:`IMAGE_NAME` does). The default value
3125      is derived using the :term:`IMAGE_BASENAME` and :term:`MACHINE`
3126      variables::
3127
3128         IMAGE_LINK_NAME ?= "${IMAGE_BASENAME}-${MACHINE}"
3129
3130
3131   :term:`IMAGE_MANIFEST`
3132      The manifest file for the image. This file lists all the installed
3133      packages that make up the image. The file contains package
3134      information on a line-per-package basis as follows::
3135
3136          packagename packagearch version
3137
3138      The :ref:`rootfs-postcommands <ref-classes-rootfs*>` class defines the manifest
3139      file as follows::
3140
3141         IMAGE_MANIFEST ="${IMGDEPLOYDIR}/${IMAGE_NAME}${IMAGE_NAME_SUFFIX}.manifest"
3142
3143      The location is
3144      derived using the :term:`IMGDEPLOYDIR`
3145      and :term:`IMAGE_NAME` variables. You can find
3146      information on how the image is created in the ":ref:`overview-manual/concepts:image generation`"
3147      section in the Yocto Project Overview and Concepts Manual.
3148
3149   :term:`IMAGE_NAME`
3150      The name of the output image files minus the extension. This variable
3151      is derived using the :term:`IMAGE_BASENAME`,
3152      :term:`MACHINE`, and :term:`IMAGE_VERSION_SUFFIX`
3153      variables::
3154
3155         IMAGE_NAME ?= "${IMAGE_BASENAME}-${MACHINE}${IMAGE_VERSION_SUFFIX}"
3156
3157   :term:`IMAGE_NAME_SUFFIX`
3158      Suffix used for the image output filename - defaults to ``".rootfs"``
3159      to distinguish the image file from other files created during image
3160      building; however if this suffix is redundant or not desired you can
3161      clear the value of this variable (set the value to ""). For example,
3162      this is typically cleared in initramfs image recipes.
3163
3164   :term:`IMAGE_OVERHEAD_FACTOR`
3165      Defines a multiplier that the build system applies to the initial
3166      image size for cases when the multiplier times the returned disk
3167      usage value for the image is greater than the sum of
3168      :term:`IMAGE_ROOTFS_SIZE` and :term:`IMAGE_ROOTFS_EXTRA_SPACE`. The result of
3169      the multiplier applied to the initial image size creates free disk
3170      space in the image as overhead. By default, the build process uses a
3171      multiplier of 1.3 for this variable. This default value results in
3172      30% free disk space added to the image when this method is used to
3173      determine the final generated image size. You should be aware that
3174      post install scripts and the package management system uses disk
3175      space inside this overhead area. Consequently, the multiplier does
3176      not produce an image with all the theoretical free disk space. See
3177      :term:`IMAGE_ROOTFS_SIZE` for information on how the build system
3178      determines the overall image size.
3179
3180      The default 30% free disk space typically gives the image enough room
3181      to boot and allows for basic post installs while still leaving a
3182      small amount of free disk space. If 30% free space is inadequate, you
3183      can increase the default value. For example, the following setting
3184      gives you 50% free space added to the image::
3185
3186         IMAGE_OVERHEAD_FACTOR = "1.5"
3187
3188      Alternatively, you can ensure a specific amount of free disk space is
3189      added to the image by using the :term:`IMAGE_ROOTFS_EXTRA_SPACE`
3190      variable.
3191
3192   :term:`IMAGE_PKGTYPE`
3193      Defines the package type (i.e. DEB, RPM, IPK, or TAR) used by the
3194      OpenEmbedded build system. The variable is defined appropriately by
3195      the :ref:`package_deb <ref-classes-package_deb>`,
3196      :ref:`package_rpm <ref-classes-package_rpm>`,
3197      :ref:`package_ipk <ref-classes-package_ipk>`, or
3198      :ref:`package_tar <ref-classes-package_tar>` class.
3199
3200      .. note::
3201
3202         The ``package_tar`` class is broken and is not supported. It is
3203         recommended that you do not use it.
3204
3205      The :ref:`populate_sdk_* <ref-classes-populate-sdk-*>` and
3206      :ref:`image <ref-classes-image>` classes use the :term:`IMAGE_PKGTYPE`
3207      for packaging up images and SDKs.
3208
3209      You should not set the :term:`IMAGE_PKGTYPE` manually. Rather, the
3210      variable is set indirectly through the appropriate
3211      :ref:`package_* <ref-classes-package>` class using the
3212      :term:`PACKAGE_CLASSES` variable. The
3213      OpenEmbedded build system uses the first package type (e.g. DEB, RPM,
3214      or IPK) that appears with the variable
3215
3216      .. note::
3217
3218         Files using the ``.tar`` format are never used as a substitute
3219         packaging format for DEB, RPM, and IPK formatted files for your image
3220         or SDK.
3221
3222   :term:`IMAGE_POSTPROCESS_COMMAND`
3223      Specifies a list of functions to call once the OpenEmbedded build
3224      system creates the final image output files. You can specify
3225      functions separated by semicolons::
3226
3227         IMAGE_POSTPROCESS_COMMAND += "function; ... "
3228
3229      If you need to pass the root filesystem path to a command within the
3230      function, you can use ``${IMAGE_ROOTFS}``, which points to the
3231      directory that becomes the root filesystem image. See the
3232      :term:`IMAGE_ROOTFS` variable for more
3233      information.
3234
3235   :term:`IMAGE_PREPROCESS_COMMAND`
3236      Specifies a list of functions to call before the OpenEmbedded build
3237      system creates the final image output files. You can specify
3238      functions separated by semicolons::
3239
3240         IMAGE_PREPROCESS_COMMAND += "function; ... "
3241
3242      If you need to pass the root filesystem path to a command within the
3243      function, you can use ``${IMAGE_ROOTFS}``, which points to the
3244      directory that becomes the root filesystem image. See the
3245      :term:`IMAGE_ROOTFS` variable for more
3246      information.
3247
3248   :term:`IMAGE_ROOTFS`
3249      The location of the root filesystem while it is under construction
3250      (i.e. during the :ref:`ref-tasks-rootfs` task). This
3251      variable is not configurable. Do not change it.
3252
3253   :term:`IMAGE_ROOTFS_ALIGNMENT`
3254      Specifies the alignment for the output image file in Kbytes. If the
3255      size of the image is not a multiple of this value, then the size is
3256      rounded up to the nearest multiple of the value. The default value is
3257      "1". See :term:`IMAGE_ROOTFS_SIZE` for
3258      additional information.
3259
3260   :term:`IMAGE_ROOTFS_EXTRA_SPACE`
3261      Defines additional free disk space created in the image in Kbytes. By
3262      default, this variable is set to "0". This free disk space is added
3263      to the image after the build system determines the image size as
3264      described in :term:`IMAGE_ROOTFS_SIZE`.
3265
3266      This variable is particularly useful when you want to ensure that a
3267      specific amount of free disk space is available on a device after an
3268      image is installed and running. For example, to be sure 5 Gbytes of
3269      free disk space is available, set the variable as follows::
3270
3271         IMAGE_ROOTFS_EXTRA_SPACE = "5242880"
3272
3273      For example, the Yocto Project Build Appliance specifically requests
3274      40 Gbytes of extra space with the line::
3275
3276         IMAGE_ROOTFS_EXTRA_SPACE = "41943040"
3277
3278   :term:`IMAGE_ROOTFS_SIZE`
3279      Defines the size in Kbytes for the generated image. The OpenEmbedded
3280      build system determines the final size for the generated image using
3281      an algorithm that takes into account the initial disk space used for
3282      the generated image, a requested size for the image, and requested
3283      additional free disk space to be added to the image. Programatically,
3284      the build system determines the final size of the generated image as
3285      follows::
3286
3287         if (image-du * overhead) < rootfs-size:
3288             internal-rootfs-size = rootfs-size + xspace
3289         else:
3290             internal-rootfs-size = (image-du * overhead) + xspace
3291         where:
3292             image-du = Returned value of the du command on the image.
3293             overhead = IMAGE_OVERHEAD_FACTOR
3294             rootfs-size = IMAGE_ROOTFS_SIZE
3295             internal-rootfs-size = Initial root filesystem size before any modifications.
3296             xspace = IMAGE_ROOTFS_EXTRA_SPACE
3297
3298      See the :term:`IMAGE_OVERHEAD_FACTOR`
3299      and :term:`IMAGE_ROOTFS_EXTRA_SPACE`
3300      variables for related information.
3301
3302   :term:`IMAGE_TYPEDEP`
3303      Specifies a dependency from one image type on another. Here is an
3304      example from the :ref:`image-live <ref-classes-image-live>` class::
3305
3306         IMAGE_TYPEDEP:live = "ext3"
3307
3308      In the previous example, the variable ensures that when "live" is
3309      listed with the :term:`IMAGE_FSTYPES` variable,
3310      the OpenEmbedded build system produces an ``ext3`` image first since
3311      one of the components of the live image is an ``ext3`` formatted
3312      partition containing the root filesystem.
3313
3314   :term:`IMAGE_TYPES`
3315      Specifies the complete list of supported image types by default:
3316
3317      - btrfs
3318      - container
3319      - cpio
3320      - cpio.gz
3321      - cpio.lz4
3322      - cpio.lzma
3323      - cpio.xz
3324      - cramfs
3325      - erofs
3326      - erofs-lz4
3327      - erofs-lz4hc
3328      - ext2
3329      - ext2.bz2
3330      - ext2.gz
3331      - ext2.lzma
3332      - ext3
3333      - ext3.gz
3334      - ext4
3335      - ext4.gz
3336      - f2fs
3337      - hddimg
3338      - iso
3339      - jffs2
3340      - jffs2.sum
3341      - multiubi
3342      - squashfs
3343      - squashfs-lz4
3344      - squashfs-lzo
3345      - squashfs-xz
3346      - tar
3347      - tar.bz2
3348      - tar.gz
3349      - tar.lz4
3350      - tar.xz
3351      - tar.zst
3352      - ubi
3353      - ubifs
3354      - wic
3355      - wic.bz2
3356      - wic.gz
3357      - wic.lzma
3358
3359      For more information about these types of images, see
3360      ``meta/classes/image_types*.bbclass`` in the :term:`Source Directory`.
3361
3362   :term:`IMAGE_VERSION_SUFFIX`
3363      Version suffix that is part of the default :term:`IMAGE_NAME` and
3364      :term:`KERNEL_ARTIFACT_NAME` values.
3365      Defaults to ``"-${DATETIME}"``, however you could set this to a
3366      version string that comes from your external build environment if
3367      desired, and this suffix would then be used consistently across
3368      the build artifacts.
3369
3370   :term:`IMGDEPLOYDIR`
3371      When inheriting the :ref:`image <ref-classes-image>` class directly or
3372      through the :ref:`core-image <ref-classes-core-image>` class, the
3373      :term:`IMGDEPLOYDIR` points to a temporary work area for deployed files
3374      that is set in the ``image`` class as follows::
3375
3376         IMGDEPLOYDIR = "${WORKDIR}/deploy-${PN}-image-complete"
3377
3378      Recipes inheriting the ``image`` class should copy files to be
3379      deployed into :term:`IMGDEPLOYDIR`, and the class will take care of
3380      copying them into :term:`DEPLOY_DIR_IMAGE` afterwards.
3381
3382   :term:`INC_PR`
3383      Helps define the recipe revision for recipes that share a common
3384      ``include`` file. You can think of this variable as part of the
3385      recipe revision as set from within an include file.
3386
3387      Suppose, for example, you have a set of recipes that are used across
3388      several projects. And, within each of those recipes the revision (its
3389      :term:`PR` value) is set accordingly. In this case, when
3390      the revision of those recipes changes, the burden is on you to find
3391      all those recipes and be sure that they get changed to reflect the
3392      updated version of the recipe. In this scenario, it can get
3393      complicated when recipes that are used in many places and provide
3394      common functionality are upgraded to a new revision.
3395
3396      A more efficient way of dealing with this situation is to set the
3397      :term:`INC_PR` variable inside the ``include`` files that the recipes
3398      share and then expand the :term:`INC_PR` variable within the recipes to
3399      help define the recipe revision.
3400
3401      The following provides an example that shows how to use the
3402      :term:`INC_PR` variable given a common ``include`` file that defines the
3403      variable. Once the variable is defined in the ``include`` file, you
3404      can use the variable to set the :term:`PR` values in each recipe. You
3405      will notice that when you set a recipe's :term:`PR` you can provide more
3406      granular revisioning by appending values to the :term:`INC_PR` variable::
3407
3408         recipes-graphics/xorg-font/xorg-font-common.inc:INC_PR = "r2"
3409         recipes-graphics/xorg-font/encodings_1.0.4.bb:PR = "${INC_PR}.1"
3410         recipes-graphics/xorg-font/font-util_1.3.0.bb:PR = "${INC_PR}.0"
3411         recipes-graphics/xorg-font/font-alias_1.0.3.bb:PR = "${INC_PR}.3"
3412
3413      The
3414      first line of the example establishes the baseline revision to be
3415      used for all recipes that use the ``include`` file. The remaining
3416      lines in the example are from individual recipes and show how the
3417      :term:`PR` value is set.
3418
3419   :term:`INCOMPATIBLE_LICENSE`
3420      Specifies a space-separated list of license names (as they would
3421      appear in :term:`LICENSE`) that should be excluded
3422      from the build. Recipes that provide no alternatives to listed
3423      incompatible licenses are not built. Packages that are individually
3424      licensed with the specified incompatible licenses will be deleted.
3425
3426      .. note::
3427
3428         This functionality is only regularly tested using the following
3429         setting::
3430
3431                 INCOMPATIBLE_LICENSE = "GPL-3.0 LGPL-3.0 AGPL-3.0"
3432
3433
3434         Although you can use other settings, you might be required to
3435         remove dependencies on or provide alternatives to components that
3436         are required to produce a functional system image.
3437
3438      .. note::
3439
3440         It is possible to define a list of licenses that are allowed to be
3441         used instead of the licenses that are excluded. To do this, define
3442         a variable ``COMPATIBLE_LICENSES`` with the names of the licenses
3443         that are allowed. Then define :term:`INCOMPATIBLE_LICENSE` as::
3444
3445                 INCOMPATIBLE_LICENSE = "${@' '.join(sorted(set(d.getVar('AVAILABLE_LICENSES').split()) - set(d.getVar('COMPATIBLE_LICENSES').split())))}"
3446
3447
3448         This will result in :term:`INCOMPATIBLE_LICENSE` containing the names of
3449         all licenses from :term:`AVAILABLE_LICENSES` except the ones specified
3450         in ``COMPATIBLE_LICENSES``, thus only allowing the latter licenses to
3451         be used.
3452
3453   :term:`INHERIT`
3454      Causes the named class or classes to be inherited globally. Anonymous
3455      functions in the class or classes are not executed for the base
3456      configuration and in each individual recipe. The OpenEmbedded build
3457      system ignores changes to :term:`INHERIT` in individual recipes.
3458
3459      For more information on :term:`INHERIT`, see the
3460      :ref:`bitbake:bitbake-user-manual/bitbake-user-manual-metadata:\`\`inherit\`\` configuration directive`"
3461      section in the Bitbake User Manual.
3462
3463   :term:`INHERIT_DISTRO`
3464      Lists classes that will be inherited at the distribution level. It is
3465      unlikely that you want to edit this variable.
3466
3467      The default value of the variable is set as follows in the
3468      ``meta/conf/distro/defaultsetup.conf`` file::
3469
3470         INHERIT_DISTRO ?= "debian devshell sstate license"
3471
3472   :term:`INHIBIT_DEFAULT_DEPS`
3473      Prevents the default dependencies, namely the C compiler and standard
3474      C library (libc), from being added to :term:`DEPENDS`.
3475      This variable is usually used within recipes that do not require any
3476      compilation using the C compiler.
3477
3478      Set the variable to "1" to prevent the default dependencies from
3479      being added.
3480
3481   :term:`INHIBIT_PACKAGE_DEBUG_SPLIT`
3482      Prevents the OpenEmbedded build system from splitting out debug
3483      information during packaging. By default, the build system splits out
3484      debugging information during the
3485      :ref:`ref-tasks-package` task. For more information on
3486      how debug information is split out, see the
3487      :term:`PACKAGE_DEBUG_SPLIT_STYLE`
3488      variable.
3489
3490      To prevent the build system from splitting out debug information
3491      during packaging, set the :term:`INHIBIT_PACKAGE_DEBUG_SPLIT` variable as
3492      follows::
3493
3494         INHIBIT_PACKAGE_DEBUG_SPLIT = "1"
3495
3496   :term:`INHIBIT_PACKAGE_STRIP`
3497      If set to "1", causes the build to not strip binaries in resulting
3498      packages and prevents the ``-dbg`` package from containing the source
3499      files.
3500
3501      By default, the OpenEmbedded build system strips binaries and puts
3502      the debugging symbols into ``${``\ :term:`PN`\ ``}-dbg``.
3503      Consequently, you should not set :term:`INHIBIT_PACKAGE_STRIP` when you
3504      plan to debug in general.
3505
3506   :term:`INHIBIT_SYSROOT_STRIP`
3507      If set to "1", causes the build to not strip binaries in the
3508      resulting sysroot.
3509
3510      By default, the OpenEmbedded build system strips binaries in the
3511      resulting sysroot. When you specifically set the
3512      :term:`INHIBIT_SYSROOT_STRIP` variable to "1" in your recipe, you inhibit
3513      this stripping.
3514
3515      If you want to use this variable, include the
3516      :ref:`staging <ref-classes-staging>` class. This class uses a
3517      ``sys_strip()`` function to test for the variable and acts
3518      accordingly.
3519
3520      .. note::
3521
3522         Use of the :term:`INHIBIT_SYSROOT_STRIP` variable occurs in rare and
3523         special circumstances. For example, suppose you are building
3524         bare-metal firmware by using an external GCC toolchain. Furthermore,
3525         even if the toolchain's binaries are strippable, there are other files
3526         needed for the build that are not strippable.
3527
3528   :term:`INITRAMFS_FSTYPES`
3529      Defines the format for the output image of an initial RAM filesystem
3530      (initramfs), which is used during boot. Supported formats are the
3531      same as those supported by the
3532      :term:`IMAGE_FSTYPES` variable.
3533
3534      The default value of this variable, which is set in the
3535      ``meta/conf/bitbake.conf`` configuration file in the
3536      :term:`Source Directory`, is "cpio.gz". The Linux kernel's
3537      initramfs mechanism, as opposed to the initial RAM filesystem
3538      `initrd <https://en.wikipedia.org/wiki/Initrd>`__ mechanism, expects
3539      an optionally compressed cpio archive.
3540
3541   :term:`INITRAMFS_IMAGE`
3542      Specifies the :term:`PROVIDES` name of an image
3543      recipe that is used to build an initial RAM filesystem (initramfs)
3544      image. In other words, the :term:`INITRAMFS_IMAGE` variable causes an
3545      additional recipe to be built as a dependency to whatever root
3546      filesystem recipe you might be using (e.g. ``core-image-sato``). The
3547      initramfs image recipe you provide should set
3548      :term:`IMAGE_FSTYPES` to
3549      :term:`INITRAMFS_FSTYPES`.
3550
3551      An initramfs image provides a temporary root filesystem used for
3552      early system initialization (e.g. loading of modules needed to locate
3553      and mount the "real" root filesystem).
3554
3555      .. note::
3556
3557         See the ``meta/recipes-core/images/core-image-minimal-initramfs.bb``
3558         recipe in the :term:`Source Directory`
3559         for an example initramfs recipe. To select this sample recipe as
3560         the one built to provide the initramfs image, set :term:`INITRAMFS_IMAGE`
3561         to "core-image-minimal-initramfs".
3562
3563      You can also find more information by referencing the
3564      ``meta-poky/conf/local.conf.sample.extended`` configuration file in
3565      the Source Directory, the :ref:`image <ref-classes-image>` class,
3566      and the :ref:`kernel <ref-classes-kernel>` class to see how to use
3567      the :term:`INITRAMFS_IMAGE` variable.
3568
3569      If :term:`INITRAMFS_IMAGE` is empty, which is the default, then no
3570      initramfs image is built.
3571
3572      For more information, you can also see the
3573      :term:`INITRAMFS_IMAGE_BUNDLE`
3574      variable, which allows the generated image to be bundled inside the
3575      kernel image. Additionally, for information on creating an initramfs
3576      image, see the ":ref:`dev-manual/common-tasks:building an initial ram filesystem (initramfs) image`" section
3577      in the Yocto Project Development Tasks Manual.
3578
3579   :term:`INITRAMFS_IMAGE_BUNDLE`
3580      Controls whether or not the image recipe specified by
3581      :term:`INITRAMFS_IMAGE` is run through an
3582      extra pass
3583      (:ref:`ref-tasks-bundle_initramfs`) during
3584      kernel compilation in order to build a single binary that contains
3585      both the kernel image and the initial RAM filesystem (initramfs)
3586      image. This makes use of the
3587      :term:`CONFIG_INITRAMFS_SOURCE` kernel
3588      feature.
3589
3590      .. note::
3591
3592         Using an extra compilation pass to bundle the initramfs avoids a
3593         circular dependency between the kernel recipe and the initramfs
3594         recipe should the initramfs include kernel modules. Should that be
3595         the case, the initramfs recipe depends on the kernel for the
3596         kernel modules, and the kernel depends on the initramfs recipe
3597         since the initramfs is bundled inside the kernel image.
3598
3599      The combined binary is deposited into the ``tmp/deploy`` directory,
3600      which is part of the :term:`Build Directory`.
3601
3602      Setting the variable to "1" in a configuration file causes the
3603      OpenEmbedded build system to generate a kernel image with the
3604      initramfs specified in :term:`INITRAMFS_IMAGE` bundled within::
3605
3606         INITRAMFS_IMAGE_BUNDLE = "1"
3607
3608      By default, the
3609      :ref:`kernel <ref-classes-kernel>` class sets this variable to a
3610      null string as follows::
3611
3612         INITRAMFS_IMAGE_BUNDLE ?= ""
3613
3614      .. note::
3615
3616         You must set the :term:`INITRAMFS_IMAGE_BUNDLE` variable in a
3617         configuration file. You cannot set the variable in a recipe file.
3618
3619      See the
3620      :yocto_git:`local.conf.sample.extended </poky/tree/meta-poky/conf/local.conf.sample.extended>`
3621      file for additional information. Also, for information on creating an
3622      initramfs, see the ":ref:`dev-manual/common-tasks:building an initial ram filesystem (initramfs) image`" section
3623      in the Yocto Project Development Tasks Manual.
3624
3625   :term:`INITRAMFS_LINK_NAME`
3626      The link name of the initial RAM filesystem image. This variable is
3627      set in the ``meta/classes/kernel-artifact-names.bbclass`` file as
3628      follows::
3629
3630         INITRAMFS_LINK_NAME ?= "initramfs-${KERNEL_ARTIFACT_LINK_NAME}"
3631
3632      The value of the
3633      ``KERNEL_ARTIFACT_LINK_NAME`` variable, which is set in the same
3634      file, has the following value::
3635
3636         KERNEL_ARTIFACT_LINK_NAME ?= "${MACHINE}"
3637
3638      See the :term:`MACHINE` variable for additional
3639      information.
3640
3641   :term:`INITRAMFS_NAME`
3642      The base name of the initial RAM filesystem image. This variable is
3643      set in the ``meta/classes/kernel-artifact-names.bbclass`` file as
3644      follows::
3645
3646         INITRAMFS_NAME ?= "initramfs-${KERNEL_ARTIFACT_NAME}"
3647
3648      The value of the :term:`KERNEL_ARTIFACT_NAME`
3649      variable, which is set in the same file, has the following value::
3650
3651         KERNEL_ARTIFACT_NAME ?= "${PKGE}-${PKGV}-${PKGR}-${MACHINE}${IMAGE_VERSION_SUFFIX}"
3652
3653   :term:`INITRD`
3654      Indicates list of filesystem images to concatenate and use as an
3655      initial RAM disk (``initrd``).
3656
3657      The :term:`INITRD` variable is an optional variable used with the
3658      :ref:`image-live <ref-classes-image-live>` class.
3659
3660   :term:`INITRD_IMAGE`
3661      When building a "live" bootable image (i.e. when
3662      :term:`IMAGE_FSTYPES` contains "live"),
3663      :term:`INITRD_IMAGE` specifies the image recipe that should be built to
3664      provide the initial RAM disk image. The default value is
3665      "core-image-minimal-initramfs".
3666
3667      See the :ref:`image-live <ref-classes-image-live>` class for more
3668      information.
3669
3670   :term:`INITSCRIPT_NAME`
3671      The filename of the initialization script as installed to
3672      ``${sysconfdir}/init.d``.
3673
3674      This variable is used in recipes when using ``update-rc.d.bbclass``.
3675      The variable is mandatory.
3676
3677   :term:`INITSCRIPT_PACKAGES`
3678      A list of the packages that contain initscripts. If multiple packages
3679      are specified, you need to append the package name to the other
3680      ``INITSCRIPT_*`` as an override.
3681
3682      This variable is used in recipes when using ``update-rc.d.bbclass``.
3683      The variable is optional and defaults to the :term:`PN`
3684      variable.
3685
3686   :term:`INITSCRIPT_PARAMS`
3687      Specifies the options to pass to ``update-rc.d``. Here is an example::
3688
3689         INITSCRIPT_PARAMS = "start 99 5 2 . stop 20 0 1 6 ."
3690
3691      In this example, the script has a runlevel of 99, starts the script
3692      in initlevels 2 and 5, and stops the script in levels 0, 1 and 6.
3693
3694      The variable's default value is "defaults", which is set in the
3695      :ref:`update-rc.d <ref-classes-update-rc.d>` class.
3696
3697      The value in :term:`INITSCRIPT_PARAMS` is passed through to the
3698      ``update-rc.d`` command. For more information on valid parameters,
3699      please see the ``update-rc.d`` manual page at
3700      https://manpages.debian.org/buster/init-system-helpers/update-rc.d.8.en.html
3701
3702   :term:`INSANE_SKIP`
3703      Specifies the QA checks to skip for a specific package within a
3704      recipe. For example, to skip the check for symbolic link ``.so``
3705      files in the main package of a recipe, add the following to the
3706      recipe. The package name override must be used, which in this example
3707      is ``${PN}``::
3708
3709         INSANE_SKIP:${PN} += "dev-so"
3710
3711      See the ":ref:`insane.bbclass <ref-classes-insane>`" section for a
3712      list of the valid QA checks you can specify using this variable.
3713
3714   :term:`INSTALL_TIMEZONE_FILE`
3715      By default, the ``tzdata`` recipe packages an ``/etc/timezone`` file.
3716      Set the :term:`INSTALL_TIMEZONE_FILE` variable to "0" at the
3717      configuration level to disable this behavior.
3718
3719   :term:`IPK_FEED_URIS`
3720      When the IPK backend is in use and package management is enabled on
3721      the target, you can use this variable to set up ``opkg`` in the
3722      target image to point to package feeds on a nominated server. Once
3723      the feed is established, you can perform installations or upgrades
3724      using the package manager at runtime.
3725
3726   :term:`KARCH`
3727      Defines the kernel architecture used when assembling the
3728      configuration. Architectures supported for this release are:
3729
3730      - powerpc
3731      - i386
3732      - x86_64
3733      - arm
3734      - qemu
3735      - mips
3736
3737      You define the :term:`KARCH` variable in the :ref:`kernel-dev/advanced:bsp descriptions`.
3738
3739   :term:`KBRANCH`
3740      A regular expression used by the build process to explicitly identify
3741      the kernel branch that is validated, patched, and configured during a
3742      build. You must set this variable to ensure the exact kernel branch
3743      you want is being used by the build process.
3744
3745      Values for this variable are set in the kernel's recipe file and the
3746      kernel's append file. For example, if you are using the
3747      ``linux-yocto_4.12`` kernel, the kernel recipe file is the
3748      ``meta/recipes-kernel/linux/linux-yocto_4.12.bb`` file. :term:`KBRANCH`
3749      is set as follows in that kernel recipe file::
3750
3751         KBRANCH ?= "standard/base"
3752
3753      This variable is also used from the kernel's append file to identify
3754      the kernel branch specific to a particular machine or target
3755      hardware. Continuing with the previous kernel example, the kernel's
3756      append file (i.e. ``linux-yocto_4.12.bbappend``) is located in the
3757      BSP layer for a given machine. For example, the append file for the
3758      Beaglebone, EdgeRouter, and generic versions of both 32 and 64-bit IA
3759      machines (``meta-yocto-bsp``) is named
3760      ``meta-yocto-bsp/recipes-kernel/linux/linux-yocto_4.12.bbappend``.
3761      Here are the related statements from that append file::
3762
3763         KBRANCH:genericx86 = "standard/base"
3764         KBRANCH:genericx86-64 = "standard/base"
3765         KBRANCH:edgerouter = "standard/edgerouter"
3766         KBRANCH:beaglebone = "standard/beaglebone"
3767
3768      The :term:`KBRANCH` statements
3769      identify the kernel branch to use when building for each supported
3770      BSP.
3771
3772   :term:`KBUILD_DEFCONFIG`
3773      When used with the :ref:`kernel-yocto <ref-classes-kernel-yocto>`
3774      class, specifies an "in-tree" kernel configuration file for use
3775      during a kernel build.
3776
3777      Typically, when using a ``defconfig`` to configure a kernel during a
3778      build, you place the file in your layer in the same manner as you
3779      would place patch files and configuration fragment files (i.e.
3780      "out-of-tree"). However, if you want to use a ``defconfig`` file that
3781      is part of the kernel tree (i.e. "in-tree"), you can use the
3782      :term:`KBUILD_DEFCONFIG` variable and append the
3783      :term:`KMACHINE` variable to point to the
3784      ``defconfig`` file.
3785
3786      To use the variable, set it in the append file for your kernel recipe
3787      using the following form::
3788
3789         KBUILD_DEFCONFIG_KMACHINE ?= defconfig_file
3790
3791      Here is an example from a "raspberrypi2" :term:`KMACHINE` build that uses
3792      a ``defconfig`` file named "bcm2709_defconfig"::
3793
3794         KBUILD_DEFCONFIG:raspberrypi2 = "bcm2709_defconfig"
3795
3796      As an alternative, you can use the following within your append file::
3797
3798         KBUILD_DEFCONFIG:pn-linux-yocto ?= "defconfig_file"
3799
3800      For more
3801      information on how to use the :term:`KBUILD_DEFCONFIG` variable, see the
3802      ":ref:`kernel-dev/common:using an "in-tree" \`\`defconfig\`\` file`"
3803      section in the Yocto Project Linux Kernel Development Manual.
3804
3805   :term:`KCONFIG_MODE`
3806      When used with the :ref:`kernel-yocto <ref-classes-kernel-yocto>`
3807      class, specifies the kernel configuration values to use for options
3808      not specified in the provided ``defconfig`` file. Valid options are::
3809
3810         KCONFIG_MODE = "alldefconfig"
3811         KCONFIG_MODE = "allnoconfig"
3812
3813      In ``alldefconfig`` mode the options not explicitly specified will be
3814      assigned their Kconfig default value. In ``allnoconfig`` mode the
3815      options not explicitly specified will be disabled in the kernel
3816      config.
3817
3818      In case :term:`KCONFIG_MODE` is not set the behaviour will depend on where
3819      the ``defconfig`` file is coming from. An "in-tree" ``defconfig`` file
3820      will be handled in ``alldefconfig`` mode, a ``defconfig`` file placed
3821      in ``${WORKDIR}`` through a meta-layer will be handled in
3822      ``allnoconfig`` mode.
3823
3824      An "in-tree" ``defconfig`` file can be selected via the
3825      :term:`KBUILD_DEFCONFIG` variable. :term:`KCONFIG_MODE` does not need to
3826      be explicitly set.
3827
3828      A ``defconfig`` file compatible with ``allnoconfig`` mode can be
3829      generated by copying the ``.config`` file from a working Linux kernel
3830      build, renaming it to ``defconfig`` and placing it into the Linux
3831      kernel ``${WORKDIR}`` through your meta-layer. :term:`KCONFIG_MODE` does
3832      not need to be explicitly set.
3833
3834      A ``defconfig`` file compatible with ``alldefconfig`` mode can be
3835      generated using the
3836      :ref:`ref-tasks-savedefconfig`
3837      task and placed into the Linux kernel ``${WORKDIR}`` through your
3838      meta-layer. Explicitely set :term:`KCONFIG_MODE`::
3839
3840         KCONFIG_MODE = "alldefconfig"
3841
3842
3843   :term:`KERNEL_ALT_IMAGETYPE`
3844      Specifies an alternate kernel image type for creation in addition to
3845      the kernel image type specified using the
3846      :term:`KERNEL_IMAGETYPE` variable.
3847
3848   :term:`KERNEL_ARTIFACT_NAME`
3849      Specifies the name of all of the build artifacts. You can change the
3850      name of the artifacts by changing the :term:`KERNEL_ARTIFACT_NAME`
3851      variable.
3852
3853      The value of :term:`KERNEL_ARTIFACT_NAME`, which is set in the
3854      ``meta/classes/kernel-artifact-names.bbclass`` file, has the
3855      following default value::
3856
3857         KERNEL_ARTIFACT_NAME ?= "${PKGE}-${PKGV}-${PKGR}-${MACHINE}${IMAGE_VERSION_SUFFIX}"
3858
3859      See the :term:`PKGE`, :term:`PKGV`, :term:`PKGR`, :term:`MACHINE`
3860      and :term:`IMAGE_VERSION_SUFFIX` variables for additional information.
3861
3862   :term:`KERNEL_CLASSES`
3863      A list of classes defining kernel image types that the
3864      :ref:`kernel <ref-classes-kernel>` class should inherit. You
3865      typically append this variable to enable extended image types. An
3866      example is the "kernel-fitimage", which enables fitImage support and
3867      resides in ``meta/classes/kernel-fitimage.bbclass``. You can register
3868      custom kernel image types with the ``kernel`` class using this
3869      variable.
3870
3871   :term:`KERNEL_DEVICETREE`
3872      Specifies the name of the generated Linux kernel device tree (i.e.
3873      the ``.dtb``) file.
3874
3875      .. note::
3876
3877         There is legacy support for specifying the full path to the device
3878         tree. However, providing just the ``.dtb`` file is preferred.
3879
3880      In order to use this variable, the
3881      :ref:`kernel-devicetree <ref-classes-kernel-devicetree>` class must
3882      be inherited.
3883
3884   :term:`KERNEL_DTB_LINK_NAME`
3885      The link name of the kernel device tree binary (DTB). This variable
3886      is set in the ``meta/classes/kernel-artifact-names.bbclass`` file as
3887      follows::
3888
3889         KERNEL_DTB_LINK_NAME ?= "${KERNEL_ARTIFACT_LINK_NAME}"
3890
3891      The
3892      value of the ``KERNEL_ARTIFACT_LINK_NAME`` variable, which is set in
3893      the same file, has the following value::
3894
3895         KERNEL_ARTIFACT_LINK_NAME ?= "${MACHINE}"
3896
3897      See the :term:`MACHINE` variable for additional
3898      information.
3899
3900   :term:`KERNEL_DTB_NAME`
3901      The base name of the kernel device tree binary (DTB). This variable
3902      is set in the ``meta/classes/kernel-artifact-names.bbclass`` file as
3903      follows::
3904
3905         KERNEL_DTB_NAME ?= "${KERNEL_ARTIFACT_NAME}"
3906
3907      The value of the :term:`KERNEL_ARTIFACT_NAME`
3908      variable, which is set in the same file, has the following value::
3909
3910         KERNEL_ARTIFACT_NAME ?= "${PKGE}-${PKGV}-${PKGR}-${MACHINE}${IMAGE_VERSION_SUFFIX}"
3911
3912   :term:`KERNEL_DTC_FLAGS`
3913      Specifies the ``dtc`` flags that are passed to the Linux kernel build
3914      system when generating the device trees (via ``DTC_FLAGS`` environment
3915      variable).
3916
3917      In order to use this variable, the
3918      :ref:`kernel-devicetree <ref-classes-kernel-devicetree>` class must
3919      be inherited.
3920
3921   :term:`KERNEL_EXTRA_ARGS`
3922      Specifies additional ``make`` command-line arguments the OpenEmbedded
3923      build system passes on when compiling the kernel.
3924
3925   :term:`KERNEL_FEATURES`
3926      Includes additional kernel metadata. In the OpenEmbedded build
3927      system, the default Board Support Packages (BSPs)
3928      :term:`Metadata` is provided through the
3929      :term:`KMACHINE` and :term:`KBRANCH`
3930      variables. You can use the :term:`KERNEL_FEATURES` variable from within
3931      the kernel recipe or kernel append file to further add metadata for
3932      all BSPs or specific BSPs.
3933
3934      The metadata you add through this variable includes config fragments
3935      and features descriptions, which usually includes patches as well as
3936      config fragments. You typically override the :term:`KERNEL_FEATURES`
3937      variable for a specific machine. In this way, you can provide
3938      validated, but optional, sets of kernel configurations and features.
3939
3940      For example, the following example from the ``linux-yocto-rt_4.12``
3941      kernel recipe adds "netfilter" and "taskstats" features to all BSPs
3942      as well as "virtio" configurations to all QEMU machines. The last two
3943      statements add specific configurations to targeted machine types::
3944
3945         KERNEL_EXTRA_FEATURES ?= "features/netfilter/netfilter.scc features/taskstats/taskstats.scc"
3946         KERNEL_FEATURES:append = "${KERNEL_EXTRA_FEATURES}"
3947         KERNEL_FEATURES:append:qemuall = "cfg/virtio.scc"
3948         KERNEL_FEATURES:append:qemux86 = " cfg/sound.scc cfg/paravirt_kvm.scc"
3949         KERNEL_FEATURES:append:qemux86-64 = "cfg/sound.scc"
3950
3951   :term:`KERNEL_FIT_LINK_NAME`
3952      The link name of the kernel flattened image tree (FIT) image. This
3953      variable is set in the ``meta/classes/kernel-artifact-names.bbclass``
3954      file as follows::
3955
3956         KERNEL_FIT_LINK_NAME ?= "${KERNEL_ARTIFACT_LINK_NAME}"
3957
3958      The value of the
3959      ``KERNEL_ARTIFACT_LINK_NAME`` variable, which is set in the same
3960      file, has the following value::
3961
3962         KERNEL_ARTIFACT_LINK_NAME ?= "${MACHINE}"
3963
3964      See the :term:`MACHINE` variable for additional
3965      information.
3966
3967   :term:`KERNEL_FIT_NAME`
3968      The base name of the kernel flattened image tree (FIT) image. This
3969      variable is set in the ``meta/classes/kernel-artifact-names.bbclass``
3970      file as follows::
3971
3972         KERNEL_FIT_NAME ?= "${KERNEL_ARTIFACT_NAME}"
3973
3974      The value of the :term:`KERNEL_ARTIFACT_NAME`
3975      variable, which is set in the same file, has the following value::
3976
3977         KERNEL_ARTIFACT_NAME ?= "${PKGE}-${PKGV}-${PKGR}-${MACHINE}${IMAGE_VERSION_SUFFIX}"
3978
3979   :term:`KERNEL_IMAGE_LINK_NAME`
3980      The link name for the kernel image. This variable is set in the
3981      ``meta/classes/kernel-artifact-names.bbclass`` file as follows::
3982
3983         KERNEL_IMAGE_LINK_NAME ?= "${KERNEL_ARTIFACT_LINK_NAME}"
3984
3985      The value of
3986      the ``KERNEL_ARTIFACT_LINK_NAME`` variable, which is set in the same
3987      file, has the following value::
3988
3989         KERNEL_ARTIFACT_LINK_NAME ?= "${MACHINE}"
3990
3991      See the :term:`MACHINE` variable for additional
3992      information.
3993
3994   :term:`KERNEL_IMAGE_MAXSIZE`
3995      Specifies the maximum size of the kernel image file in kilobytes. If
3996      :term:`KERNEL_IMAGE_MAXSIZE` is set, the size of the kernel image file is
3997      checked against the set value during the
3998      :ref:`ref-tasks-sizecheck` task. The task fails if
3999      the kernel image file is larger than the setting.
4000
4001      :term:`KERNEL_IMAGE_MAXSIZE` is useful for target devices that have a
4002      limited amount of space in which the kernel image must be stored.
4003
4004      By default, this variable is not set, which means the size of the
4005      kernel image is not checked.
4006
4007   :term:`KERNEL_IMAGE_NAME`
4008      The base name of the kernel image. This variable is set in the
4009      ``meta/classes/kernel-artifact-names.bbclass`` file as follows::
4010
4011         KERNEL_IMAGE_NAME ?= "${KERNEL_ARTIFACT_NAME}"
4012
4013      The value of the
4014      :term:`KERNEL_ARTIFACT_NAME` variable,
4015      which is set in the same file, has the following value::
4016
4017         KERNEL_ARTIFACT_NAME ?= "${PKGE}-${PKGV}-${PKGR}-${MACHINE}${IMAGE_VERSION_SUFFIX}"
4018
4019   :term:`KERNEL_IMAGETYPE`
4020      The type of kernel to build for a device, usually set by the machine
4021      configuration files and defaults to "zImage". This variable is used
4022      when building the kernel and is passed to ``make`` as the target to
4023      build.
4024
4025      If you want to build an alternate kernel image type in addition to that
4026      specified by :term:`KERNEL_IMAGETYPE`, use the :term:`KERNEL_ALT_IMAGETYPE`
4027      variable.
4028
4029   :term:`KERNEL_MODULE_AUTOLOAD`
4030      Lists kernel modules that need to be auto-loaded during boot.
4031
4032      .. note::
4033
4034         This variable replaces the deprecated :term:`module_autoload`
4035         variable.
4036
4037      You can use the :term:`KERNEL_MODULE_AUTOLOAD` variable anywhere that it
4038      can be recognized by the kernel recipe or by an out-of-tree kernel
4039      module recipe (e.g. a machine configuration file, a distribution
4040      configuration file, an append file for the recipe, or the recipe
4041      itself).
4042
4043      Specify it as follows::
4044
4045         KERNEL_MODULE_AUTOLOAD += "module_name1 module_name2 module_name3"
4046
4047      Including :term:`KERNEL_MODULE_AUTOLOAD` causes the OpenEmbedded build
4048      system to populate the ``/etc/modules-load.d/modname.conf`` file with
4049      the list of modules to be auto-loaded on boot. The modules appear
4050      one-per-line in the file. Here is an example of the most common use
4051      case::
4052
4053         KERNEL_MODULE_AUTOLOAD += "module_name"
4054
4055      For information on how to populate the ``modname.conf`` file with
4056      ``modprobe.d`` syntax lines, see the :term:`KERNEL_MODULE_PROBECONF` variable.
4057
4058   :term:`KERNEL_MODULE_PROBECONF`
4059      Provides a list of modules for which the OpenEmbedded build system
4060      expects to find ``module_conf_``\ modname values that specify
4061      configuration for each of the modules. For information on how to
4062      provide those module configurations, see the
4063      :term:`module_conf_* <module_conf>` variable.
4064
4065   :term:`KERNEL_PATH`
4066      The location of the kernel sources. This variable is set to the value
4067      of the :term:`STAGING_KERNEL_DIR` within
4068      the :ref:`module <ref-classes-module>` class. For information on
4069      how this variable is used, see the
4070      ":ref:`kernel-dev/common:incorporating out-of-tree modules`"
4071      section in the Yocto Project Linux Kernel Development Manual.
4072
4073      To help maximize compatibility with out-of-tree drivers used to build
4074      modules, the OpenEmbedded build system also recognizes and uses the
4075      :term:`KERNEL_SRC` variable, which is identical to
4076      the :term:`KERNEL_PATH` variable. Both variables are common variables
4077      used by external Makefiles to point to the kernel source directory.
4078
4079   :term:`KERNEL_SRC`
4080      The location of the kernel sources. This variable is set to the value
4081      of the :term:`STAGING_KERNEL_DIR` within
4082      the :ref:`module <ref-classes-module>` class. For information on
4083      how this variable is used, see the
4084      ":ref:`kernel-dev/common:incorporating out-of-tree modules`"
4085      section in the Yocto Project Linux Kernel Development Manual.
4086
4087      To help maximize compatibility with out-of-tree drivers used to build
4088      modules, the OpenEmbedded build system also recognizes and uses the
4089      :term:`KERNEL_PATH` variable, which is identical
4090      to the :term:`KERNEL_SRC` variable. Both variables are common variables
4091      used by external Makefiles to point to the kernel source directory.
4092
4093   :term:`KERNEL_VERSION`
4094      Specifies the version of the kernel as extracted from ``version.h``
4095      or ``utsrelease.h`` within the kernel sources. Effects of setting
4096      this variable do not take affect until the kernel has been
4097      configured. Consequently, attempting to refer to this variable in
4098      contexts prior to configuration will not work.
4099
4100   :term:`KERNELDEPMODDEPEND`
4101      Specifies whether the data referenced through
4102      :term:`PKGDATA_DIR` is needed or not.
4103      :term:`KERNELDEPMODDEPEND` does not control whether or not that data
4104      exists, but simply whether or not it is used. If you do not need to
4105      use the data, set the :term:`KERNELDEPMODDEPEND` variable in your
4106      ``initramfs`` recipe. Setting the variable there when the data is not
4107      needed avoids a potential dependency loop.
4108
4109   :term:`KFEATURE_DESCRIPTION`
4110      Provides a short description of a configuration fragment. You use
4111      this variable in the ``.scc`` file that describes a configuration
4112      fragment file. Here is the variable used in a file named ``smp.scc``
4113      to describe SMP being enabled::
4114
4115          define KFEATURE_DESCRIPTION "Enable SMP"
4116
4117   :term:`KMACHINE`
4118      The machine as known by the kernel. Sometimes the machine name used
4119      by the kernel does not match the machine name used by the
4120      OpenEmbedded build system. For example, the machine name that the
4121      OpenEmbedded build system understands as ``core2-32-intel-common``
4122      goes by a different name in the Linux Yocto kernel. The kernel
4123      understands that machine as ``intel-core2-32``. For cases like these,
4124      the :term:`KMACHINE` variable maps the kernel machine name to the
4125      OpenEmbedded build system machine name.
4126
4127      These mappings between different names occur in the Yocto Linux
4128      Kernel's ``meta`` branch. As an example take a look in the
4129      ``common/recipes-kernel/linux/linux-yocto_3.19.bbappend`` file::
4130
4131         LINUX_VERSION:core2-32-intel-common = "3.19.0"
4132         COMPATIBLE_MACHINE:core2-32-intel-common = "${MACHINE}"
4133         SRCREV_meta:core2-32-intel-common = "8897ef68b30e7426bc1d39895e71fb155d694974"
4134         SRCREV_machine:core2-32-intel-common = "43b9eced9ba8a57add36af07736344dcc383f711"
4135         KMACHINE:core2-32-intel-common = "intel-core2-32"
4136         KBRANCH:core2-32-intel-common = "standard/base"
4137         KERNEL_FEATURES:append:core2-32-intel-common = "${KERNEL_FEATURES_INTEL_COMMON}"
4138
4139      The :term:`KMACHINE` statement says
4140      that the kernel understands the machine name as "intel-core2-32".
4141      However, the OpenEmbedded build system understands the machine as
4142      "core2-32-intel-common".
4143
4144   :term:`KTYPE`
4145      Defines the kernel type to be used in assembling the configuration.
4146      The linux-yocto recipes define "standard", "tiny", and "preempt-rt"
4147      kernel types. See the ":ref:`kernel-dev/advanced:kernel types`"
4148      section in the
4149      Yocto Project Linux Kernel Development Manual for more information on
4150      kernel types.
4151
4152      You define the :term:`KTYPE` variable in the
4153      :ref:`kernel-dev/advanced:bsp descriptions`. The
4154      value you use must match the value used for the
4155      :term:`LINUX_KERNEL_TYPE` value used by the
4156      kernel recipe.
4157
4158   :term:`LABELS`
4159      Provides a list of targets for automatic configuration.
4160
4161      See the :ref:`grub-efi <ref-classes-grub-efi>` class for more
4162      information on how this variable is used.
4163
4164   :term:`LAYERDEPENDS`
4165      Lists the layers, separated by spaces, on which this recipe depends.
4166      Optionally, you can specify a specific layer version for a dependency
4167      by adding it to the end of the layer name. Here is an example::
4168
4169         LAYERDEPENDS_mylayer = "anotherlayer (=3)"
4170
4171      In this previous example,
4172      version 3 of "anotherlayer" is compared against
4173      :term:`LAYERVERSION`\ ``_anotherlayer``.
4174
4175      An error is produced if any dependency is missing or the version
4176      numbers (if specified) do not match exactly. This variable is used in
4177      the ``conf/layer.conf`` file and must be suffixed with the name of
4178      the specific layer (e.g. ``LAYERDEPENDS_mylayer``).
4179
4180   :term:`LAYERDIR`
4181      When used inside the ``layer.conf`` configuration file, this variable
4182      provides the path of the current layer. This variable is not
4183      available outside of ``layer.conf`` and references are expanded
4184      immediately when parsing of the file completes.
4185
4186   :term:`LAYERRECOMMENDS`
4187      Lists the layers, separated by spaces, recommended for use with this
4188      layer.
4189
4190      Optionally, you can specify a specific layer version for a
4191      recommendation by adding the version to the end of the layer name.
4192      Here is an example::
4193
4194         LAYERRECOMMENDS_mylayer = "anotherlayer (=3)"
4195
4196      In this previous example, version 3 of "anotherlayer" is compared
4197      against ``LAYERVERSION_anotherlayer``.
4198
4199      This variable is used in the ``conf/layer.conf`` file and must be
4200      suffixed with the name of the specific layer (e.g.
4201      ``LAYERRECOMMENDS_mylayer``).
4202
4203   :term:`LAYERSERIES_COMPAT`
4204      Lists the versions of the :term:`OpenEmbedded-Core (OE-Core)` for which
4205      a layer is compatible. Using the :term:`LAYERSERIES_COMPAT` variable
4206      allows the layer maintainer to indicate which combinations of the
4207      layer and OE-Core can be expected to work. The variable gives the
4208      system a way to detect when a layer has not been tested with new
4209      releases of OE-Core (e.g. the layer is not maintained).
4210
4211      To specify the OE-Core versions for which a layer is compatible, use
4212      this variable in your layer's ``conf/layer.conf`` configuration file.
4213      For the list, use the Yocto Project
4214      :yocto_wiki:`Release Name </Releases>` (e.g.
4215      &DISTRO_NAME_NO_CAP;). To specify multiple OE-Core versions for the
4216      layer, use a space-separated list::
4217
4218         LAYERSERIES_COMPAT_layer_root_name = "&DISTRO_NAME_NO_CAP; &DISTRO_NAME_NO_CAP_MINUS_ONE;"
4219
4220      .. note::
4221
4222         Setting :term:`LAYERSERIES_COMPAT` is required by the Yocto Project
4223         Compatible version 2 standard.
4224         The OpenEmbedded build system produces a warning if the variable
4225         is not set for any given layer.
4226
4227      See the ":ref:`dev-manual/common-tasks:creating your own layer`"
4228      section in the Yocto Project Development Tasks Manual.
4229
4230   :term:`LAYERVERSION`
4231      Optionally specifies the version of a layer as a single number. You
4232      can use this within :term:`LAYERDEPENDS` for
4233      another layer in order to depend on a specific version of the layer.
4234      This variable is used in the ``conf/layer.conf`` file and must be
4235      suffixed with the name of the specific layer (e.g.
4236      ``LAYERVERSION_mylayer``).
4237
4238   :term:`LD`
4239      The minimal command and arguments used to run the linker.
4240
4241   :term:`LDFLAGS`
4242      Specifies the flags to pass to the linker. This variable is exported
4243      to an environment variable and thus made visible to the software
4244      being built during the compilation step.
4245
4246      Default initialization for :term:`LDFLAGS` varies depending on what is
4247      being built:
4248
4249      -  :term:`TARGET_LDFLAGS` when building for the
4250         target
4251
4252      -  :term:`BUILD_LDFLAGS` when building for the
4253         build host (i.e. ``-native``)
4254
4255      -  :term:`BUILDSDK_LDFLAGS` when building for
4256         an SDK (i.e. ``nativesdk-``)
4257
4258   :term:`LEAD_SONAME`
4259      Specifies the lead (or primary) compiled library file (i.e. ``.so``)
4260      that the :ref:`debian <ref-classes-debian>` class applies its
4261      naming policy to given a recipe that packages multiple libraries.
4262
4263      This variable works in conjunction with the ``debian`` class.
4264
4265   :term:`LIC_FILES_CHKSUM`
4266      Checksums of the license text in the recipe source code.
4267
4268      This variable tracks changes in license text of the source code
4269      files. If the license text is changed, it will trigger a build
4270      failure, which gives the developer an opportunity to review any
4271      license change.
4272
4273      This variable must be defined for all recipes (unless
4274      :term:`LICENSE` is set to "CLOSED").
4275
4276      For more information, see the ":ref:`dev-manual/common-tasks:tracking license changes`"
4277      section in the Yocto Project Development Tasks Manual.
4278
4279   :term:`LICENSE`
4280      The list of source licenses for the recipe. Follow these rules:
4281
4282      -  Do not use spaces within individual license names.
4283
4284      -  Separate license names using \| (pipe) when there is a choice
4285         between licenses.
4286
4287      -  Separate license names using & (ampersand) when there are
4288         multiple licenses for different parts of the source.
4289
4290      -  You can use spaces between license names.
4291
4292      -  For standard licenses, use the names of the files in
4293         ``meta/files/common-licenses/`` or the
4294         :term:`SPDXLICENSEMAP` flag names defined in
4295         ``meta/conf/licenses.conf``.
4296
4297      Here are some examples::
4298
4299         LICENSE = "LGPLv2.1 | GPLv3"
4300         LICENSE = "MPL-1 & LGPLv2.1"
4301         LICENSE = "GPLv2+"
4302
4303      The first example is from the
4304      recipes for Qt, which the user may choose to distribute under either
4305      the LGPL version 2.1 or GPL version 3. The second example is from
4306      Cairo where two licenses cover different parts of the source code.
4307      The final example is from ``sysstat``, which presents a single
4308      license.
4309
4310      You can also specify licenses on a per-package basis to handle
4311      situations where components of the output have different licenses.
4312      For example, a piece of software whose code is licensed under GPLv2
4313      but has accompanying documentation licensed under the GNU Free
4314      Documentation License 1.2 could be specified as follows::
4315
4316         LICENSE = "GFDL-1.2 & GPLv2"
4317         LICENSE:${PN} = "GPLv2"
4318         LICENSE:${PN}-doc = "GFDL-1.2"
4319
4320   :term:`LICENSE_CREATE_PACKAGE`
4321      Setting :term:`LICENSE_CREATE_PACKAGE` to "1" causes the OpenEmbedded
4322      build system to create an extra package (i.e.
4323      ``${``\ :term:`PN`\ ``}-lic``) for each recipe and to add
4324      those packages to the
4325      :term:`RRECOMMENDS`\ ``:${PN}``.
4326
4327      The ``${PN}-lic`` package installs a directory in
4328      ``/usr/share/licenses`` named ``${PN}``, which is the recipe's base
4329      name, and installs files in that directory that contain license and
4330      copyright information (i.e. copies of the appropriate license files
4331      from ``meta/common-licenses`` that match the licenses specified in
4332      the :term:`LICENSE` variable of the recipe metadata
4333      and copies of files marked in
4334      :term:`LIC_FILES_CHKSUM` as containing
4335      license text).
4336
4337      For related information on providing license text, see the
4338      :term:`COPY_LIC_DIRS` variable, the
4339      :term:`COPY_LIC_MANIFEST` variable, and the
4340      ":ref:`dev-manual/common-tasks:providing license text`"
4341      section in the Yocto Project Development Tasks Manual.
4342
4343   :term:`LICENSE_FLAGS`
4344      Specifies additional flags for a recipe you must whitelist through
4345      :term:`LICENSE_FLAGS_WHITELIST` in
4346      order to allow the recipe to be built. When providing multiple flags,
4347      separate them with spaces.
4348
4349      This value is independent of :term:`LICENSE` and is
4350      typically used to mark recipes that might require additional licenses
4351      in order to be used in a commercial product. For more information,
4352      see the
4353      ":ref:`dev-manual/common-tasks:enabling commercially licensed recipes`"
4354      section in the Yocto Project Development Tasks Manual.
4355
4356   :term:`LICENSE_FLAGS_WHITELIST`
4357      Lists license flags that when specified in
4358      :term:`LICENSE_FLAGS` within a recipe should not
4359      prevent that recipe from being built. This practice is otherwise
4360      known as "whitelisting" license flags. For more information, see the
4361      ":ref:`dev-manual/common-tasks:enabling commercially licensed recipes`"
4362      section in the Yocto Project Development Tasks Manual.
4363
4364   :term:`LICENSE_PATH`
4365      Path to additional licenses used during the build. By default, the
4366      OpenEmbedded build system uses :term:`COMMON_LICENSE_DIR` to define the
4367      directory that holds common license text used during the build. The
4368      :term:`LICENSE_PATH` variable allows you to extend that location to other
4369      areas that have additional licenses::
4370
4371         LICENSE_PATH += "path-to-additional-common-licenses"
4372
4373   :term:`LINUX_KERNEL_TYPE`
4374      Defines the kernel type to be used in assembling the configuration.
4375      The linux-yocto recipes define "standard", "tiny", and "preempt-rt"
4376      kernel types. See the ":ref:`kernel-dev/advanced:kernel types`"
4377      section in the
4378      Yocto Project Linux Kernel Development Manual for more information on
4379      kernel types.
4380
4381      If you do not specify a :term:`LINUX_KERNEL_TYPE`, it defaults to
4382      "standard". Together with :term:`KMACHINE`, the
4383      :term:`LINUX_KERNEL_TYPE` variable defines the search arguments used by
4384      the kernel tools to find the appropriate description within the
4385      kernel :term:`Metadata` with which to build out the sources
4386      and configuration.
4387
4388   :term:`LINUX_VERSION`
4389      The Linux version from ``kernel.org`` on which the Linux kernel image
4390      being built using the OpenEmbedded build system is based. You define
4391      this variable in the kernel recipe. For example, the
4392      ``linux-yocto-3.4.bb`` kernel recipe found in
4393      ``meta/recipes-kernel/linux`` defines the variables as follows::
4394
4395         LINUX_VERSION ?= "3.4.24"
4396
4397      The :term:`LINUX_VERSION` variable is used to define :term:`PV`
4398      for the recipe::
4399
4400         PV = "${LINUX_VERSION}+git${SRCPV}"
4401
4402   :term:`LINUX_VERSION_EXTENSION`
4403      A string extension compiled into the version string of the Linux
4404      kernel built with the OpenEmbedded build system. You define this
4405      variable in the kernel recipe. For example, the linux-yocto kernel
4406      recipes all define the variable as follows::
4407
4408         LINUX_VERSION_EXTENSION ?= "-yocto-${LINUX_KERNEL_TYPE}"
4409
4410      Defining this variable essentially sets the Linux kernel
4411      configuration item ``CONFIG_LOCALVERSION``, which is visible through
4412      the ``uname`` command. Here is an example that shows the extension
4413      assuming it was set as previously shown::
4414
4415         $ uname -r
4416         3.7.0-rc8-custom
4417
4418   :term:`LOG_DIR`
4419      Specifies the directory to which the OpenEmbedded build system writes
4420      overall log files. The default directory is ``${TMPDIR}/log``.
4421
4422      For the directory containing logs specific to each task, see the
4423      :term:`T` variable.
4424
4425   :term:`MACHINE`
4426      Specifies the target device for which the image is built. You define
4427      :term:`MACHINE` in the ``local.conf`` file found in the
4428      :term:`Build Directory`. By default, :term:`MACHINE` is set to
4429      "qemux86", which is an x86-based architecture machine to be emulated
4430      using QEMU::
4431
4432         MACHINE ?= "qemux86"
4433
4434      The variable corresponds to a machine configuration file of the same
4435      name, through which machine-specific configurations are set. Thus,
4436      when :term:`MACHINE` is set to "qemux86", the corresponding
4437      ``qemux86.conf`` machine configuration file can be found in
4438      the :term:`Source Directory` in
4439      ``meta/conf/machine``.
4440
4441      The list of machines supported by the Yocto Project as shipped
4442      include the following::
4443
4444         MACHINE ?= "qemuarm"
4445         MACHINE ?= "qemuarm64"
4446         MACHINE ?= "qemumips"
4447         MACHINE ?= "qemumips64"
4448         MACHINE ?= "qemuppc"
4449         MACHINE ?= "qemux86"
4450         MACHINE ?= "qemux86-64"
4451         MACHINE ?= "genericx86"
4452         MACHINE ?= "genericx86-64"
4453         MACHINE ?= "beaglebone"
4454         MACHINE ?= "edgerouter"
4455
4456      The last five are Yocto Project reference hardware
4457      boards, which are provided in the ``meta-yocto-bsp`` layer.
4458
4459      .. note::
4460
4461         Adding additional Board Support Package (BSP) layers to your
4462         configuration adds new possible settings for :term:`MACHINE`.
4463
4464   :term:`MACHINE_ARCH`
4465      Specifies the name of the machine-specific architecture. This
4466      variable is set automatically from :term:`MACHINE` or
4467      :term:`TUNE_PKGARCH`. You should not hand-edit
4468      the :term:`MACHINE_ARCH` variable.
4469
4470   :term:`MACHINE_ESSENTIAL_EXTRA_RDEPENDS`
4471      A list of required machine-specific packages to install as part of
4472      the image being built. The build process depends on these packages
4473      being present. Furthermore, because this is a "machine-essential"
4474      variable, the list of packages are essential for the machine to boot.
4475      The impact of this variable affects images based on
4476      ``packagegroup-core-boot``, including the ``core-image-minimal``
4477      image.
4478
4479      This variable is similar to the
4480      :term:`MACHINE_ESSENTIAL_EXTRA_RRECOMMENDS` variable with the exception
4481      that the image being built has a build dependency on the variable's
4482      list of packages. In other words, the image will not build if a file
4483      in this list is not found.
4484
4485      As an example, suppose the machine for which you are building
4486      requires ``example-init`` to be run during boot to initialize the
4487      hardware. In this case, you would use the following in the machine's
4488      ``.conf`` configuration file::
4489
4490         MACHINE_ESSENTIAL_EXTRA_RDEPENDS += "example-init"
4491
4492   :term:`MACHINE_ESSENTIAL_EXTRA_RRECOMMENDS`
4493      A list of recommended machine-specific packages to install as part of
4494      the image being built. The build process does not depend on these
4495      packages being present. However, because this is a
4496      "machine-essential" variable, the list of packages are essential for
4497      the machine to boot. The impact of this variable affects images based
4498      on ``packagegroup-core-boot``, including the ``core-image-minimal``
4499      image.
4500
4501      This variable is similar to the :term:`MACHINE_ESSENTIAL_EXTRA_RDEPENDS`
4502      variable with the exception that the image being built does not have
4503      a build dependency on the variable's list of packages. In other
4504      words, the image will still build if a package in this list is not
4505      found. Typically, this variable is used to handle essential kernel
4506      modules, whose functionality may be selected to be built into the
4507      kernel rather than as a module, in which case a package will not be
4508      produced.
4509
4510      Consider an example where you have a custom kernel where a specific
4511      touchscreen driver is required for the machine to be usable. However,
4512      the driver can be built as a module or into the kernel depending on
4513      the kernel configuration. If the driver is built as a module, you
4514      want it to be installed. But, when the driver is built into the
4515      kernel, you still want the build to succeed. This variable sets up a
4516      "recommends" relationship so that in the latter case, the build will
4517      not fail due to the missing package. To accomplish this, assuming the
4518      package for the module was called ``kernel-module-ab123``, you would
4519      use the following in the machine's ``.conf`` configuration file::
4520
4521         MACHINE_ESSENTIAL_EXTRA_RRECOMMENDS += "kernel-module-ab123"
4522
4523      .. note::
4524
4525         In this example, the ``kernel-module-ab123`` recipe needs to
4526         explicitly set its :term:`PACKAGES` variable to ensure that BitBake
4527         does not use the kernel recipe's :term:`PACKAGES_DYNAMIC` variable to
4528         satisfy the dependency.
4529
4530      Some examples of these machine essentials are flash, screen,
4531      keyboard, mouse, or touchscreen drivers (depending on the machine).
4532
4533   :term:`MACHINE_EXTRA_RDEPENDS`
4534      A list of machine-specific packages to install as part of the image
4535      being built that are not essential for the machine to boot. However,
4536      the build process for more fully-featured images depends on the
4537      packages being present.
4538
4539      This variable affects all images based on ``packagegroup-base``,
4540      which does not include the ``core-image-minimal`` or
4541      ``core-image-full-cmdline`` images.
4542
4543      The variable is similar to the :term:`MACHINE_EXTRA_RRECOMMENDS` variable
4544      with the exception that the image being built has a build dependency
4545      on the variable's list of packages. In other words, the image will
4546      not build if a file in this list is not found.
4547
4548      An example is a machine that has WiFi capability but is not essential
4549      for the machine to boot the image. However, if you are building a
4550      more fully-featured image, you want to enable the WiFi. The package
4551      containing the firmware for the WiFi hardware is always expected to
4552      exist, so it is acceptable for the build process to depend upon
4553      finding the package. In this case, assuming the package for the
4554      firmware was called ``wifidriver-firmware``, you would use the
4555      following in the ``.conf`` file for the machine::
4556
4557         MACHINE_EXTRA_RDEPENDS += "wifidriver-firmware"
4558
4559   :term:`MACHINE_EXTRA_RRECOMMENDS`
4560      A list of machine-specific packages to install as part of the image
4561      being built that are not essential for booting the machine. The image
4562      being built has no build dependency on this list of packages.
4563
4564      This variable affects only images based on ``packagegroup-base``,
4565      which does not include the ``core-image-minimal`` or
4566      ``core-image-full-cmdline`` images.
4567
4568      This variable is similar to the :term:`MACHINE_EXTRA_RDEPENDS` variable
4569      with the exception that the image being built does not have a build
4570      dependency on the variable's list of packages. In other words, the
4571      image will build if a file in this list is not found.
4572
4573      An example is a machine that has WiFi capability but is not essential
4574      For the machine to boot the image. However, if you are building a
4575      more fully-featured image, you want to enable WiFi. In this case, the
4576      package containing the WiFi kernel module will not be produced if the
4577      WiFi driver is built into the kernel, in which case you still want
4578      the build to succeed instead of failing as a result of the package
4579      not being found. To accomplish this, assuming the package for the
4580      module was called ``kernel-module-examplewifi``, you would use the
4581      following in the ``.conf`` file for the machine::
4582
4583         MACHINE_EXTRA_RRECOMMENDS += "kernel-module-examplewifi"
4584
4585   :term:`MACHINE_FEATURES`
4586      Specifies the list of hardware features the
4587      :term:`MACHINE` is capable of supporting. For related
4588      information on enabling features, see the
4589      :term:`DISTRO_FEATURES`,
4590      :term:`COMBINED_FEATURES`, and
4591      :term:`IMAGE_FEATURES` variables.
4592
4593      For a list of hardware features supported by the Yocto Project as
4594      shipped, see the ":ref:`ref-features-machine`" section.
4595
4596   :term:`MACHINE_FEATURES_BACKFILL`
4597      Features to be added to :term:`MACHINE_FEATURES` if not also present in
4598      :term:`MACHINE_FEATURES_BACKFILL_CONSIDERED`.
4599
4600      This variable is set in the ``meta/conf/bitbake.conf`` file. It is
4601      not intended to be user-configurable. It is best to just reference
4602      the variable to see which machine features are being backfilled for
4603      all machine configurations. See the ":ref:`ref-features-backfill`"
4604      section for more information.
4605
4606   :term:`MACHINE_FEATURES_BACKFILL_CONSIDERED`
4607      Features from :term:`MACHINE_FEATURES_BACKFILL` that should not be
4608      backfilled (i.e. added to :term:`MACHINE_FEATURES`) during the build. See
4609      the ":ref:`ref-features-backfill`" section for more information.
4610
4611   :term:`MACHINEOVERRIDES`
4612      A colon-separated list of overrides that apply to the current
4613      machine. By default, this list includes the value of
4614      :term:`MACHINE`.
4615
4616      You can extend :term:`MACHINEOVERRIDES` to add extra overrides that
4617      should apply to a machine. For example, all machines emulated in QEMU
4618      (e.g. ``qemuarm``, ``qemux86``, and so forth) include a file named
4619      ``meta/conf/machine/include/qemu.inc`` that prepends the following
4620      override to :term:`MACHINEOVERRIDES`::
4621
4622         MACHINEOVERRIDES =. "qemuall:"
4623
4624      This
4625      override allows variables to be overridden for all machines emulated
4626      in QEMU, like in the following example from the ``connman-conf``
4627      recipe::
4628
4629         SRC_URI:append:qemuall = " file://wired.config \
4630             file://wired-setup \
4631             "
4632
4633      The underlying mechanism behind
4634      :term:`MACHINEOVERRIDES` is simply that it is included in the default
4635      value of :term:`OVERRIDES`.
4636
4637   :term:`MAINTAINER`
4638      The email address of the distribution maintainer.
4639
4640   :term:`METADATA_BRANCH`
4641      The branch currently checked out for the OpenEmbedded-Core layer (path
4642      determined by :term:`COREBASE`).
4643
4644   :term:`METADATA_REVISION`
4645      The revision currently checked out for the OpenEmbedded-Core layer (path
4646      determined by :term:`COREBASE`).
4647
4648   :term:`MIRRORS`
4649      Specifies additional paths from which the OpenEmbedded build system
4650      gets source code. When the build system searches for source code, it
4651      first tries the local download directory. If that location fails, the
4652      build system tries locations defined by
4653      :term:`PREMIRRORS`, the upstream source, and then
4654      locations specified by :term:`MIRRORS` in that order.
4655
4656      Assuming your distribution (:term:`DISTRO`) is "poky",
4657      the default value for :term:`MIRRORS` is defined in the
4658      ``conf/distro/poky.conf`` file in the ``meta-poky`` Git repository.
4659
4660   :term:`MLPREFIX`
4661      Specifies a prefix has been added to :term:`PN` to create a
4662      special version of a recipe or package (i.e. a Multilib version). The
4663      variable is used in places where the prefix needs to be added to or
4664      removed from a the name (e.g. the :term:`BPN` variable).
4665      :term:`MLPREFIX` gets set when a prefix has been added to :term:`PN`.
4666
4667      .. note::
4668
4669         The "ML" in :term:`MLPREFIX` stands for "MultiLib". This representation is
4670         historical and comes from a time when ``nativesdk`` was a suffix
4671         rather than a prefix on the recipe name. When ``nativesdk`` was turned
4672         into a prefix, it made sense to set :term:`MLPREFIX` for it as well.
4673
4674      To help understand when :term:`MLPREFIX` might be needed, consider when
4675      :term:`BBCLASSEXTEND` is used to provide a
4676      ``nativesdk`` version of a recipe in addition to the target version.
4677      If that recipe declares build-time dependencies on tasks in other
4678      recipes by using :term:`DEPENDS`, then a dependency on
4679      "foo" will automatically get rewritten to a dependency on
4680      "nativesdk-foo". However, dependencies like the following will not
4681      get rewritten automatically::
4682
4683         do_foo[depends] += "recipe:do_foo"
4684
4685      If you want such a dependency to also get transformed, you can do the
4686      following::
4687
4688         do_foo[depends] += "${MLPREFIX}recipe:do_foo"
4689
4690   :term:`module_autoload`
4691      This variable has been replaced by the :term:`KERNEL_MODULE_AUTOLOAD`
4692      variable. You should replace all occurrences of :term:`module_autoload`
4693      with additions to :term:`KERNEL_MODULE_AUTOLOAD`, for example::
4694
4695         module_autoload_rfcomm = "rfcomm"
4696
4697      should now be replaced with::
4698
4699         KERNEL_MODULE_AUTOLOAD += "rfcomm"
4700
4701      See the :term:`KERNEL_MODULE_AUTOLOAD` variable for more information.
4702
4703   :term:`module_conf`
4704      Specifies `modprobe.d <https://linux.die.net/man/5/modprobe.d>`_
4705      syntax lines for inclusion in the ``/etc/modprobe.d/modname.conf``
4706      file.
4707
4708      You can use this variable anywhere that it can be recognized by the
4709      kernel recipe or out-of-tree kernel module recipe (e.g. a machine
4710      configuration file, a distribution configuration file, an append file
4711      for the recipe, or the recipe itself). If you use this variable, you
4712      must also be sure to list the module name in the
4713      :term:`KERNEL_MODULE_AUTOLOAD`
4714      variable.
4715
4716      Here is the general syntax::
4717
4718         module_conf_module_name = "modprobe.d-syntax"
4719
4720      You must use the kernel module name override.
4721
4722      Run ``man modprobe.d`` in the shell to find out more information on
4723      the exact syntax you want to provide with :term:`module_conf`.
4724
4725      Including :term:`module_conf` causes the OpenEmbedded build system to
4726      populate the ``/etc/modprobe.d/modname.conf`` file with
4727      ``modprobe.d`` syntax lines. Here is an example that adds the options
4728      ``arg1`` and ``arg2`` to a module named ``mymodule``::
4729
4730         module_conf_mymodule = "options mymodule arg1=val1 arg2=val2"
4731
4732      For information on how to specify kernel modules to auto-load on
4733      boot, see the :term:`KERNEL_MODULE_AUTOLOAD` variable.
4734
4735   :term:`MODULE_TARBALL_DEPLOY`
4736      Controls creation of the ``modules-*.tgz`` file. Set this variable to
4737      "0" to disable creation of this file, which contains all of the
4738      kernel modules resulting from a kernel build.
4739
4740   :term:`MODULE_TARBALL_LINK_NAME`
4741      The link name of the kernel module tarball. This variable is set in
4742      the ``meta/classes/kernel-artifact-names.bbclass`` file as follows::
4743
4744         MODULE_TARBALL_LINK_NAME ?= "${KERNEL_ARTIFACT_LINK_NAME}"
4745
4746      The value
4747      of the ``KERNEL_ARTIFACT_LINK_NAME`` variable, which is set in the
4748      same file, has the following value::
4749
4750         KERNEL_ARTIFACT_LINK_NAME ?= "${MACHINE}"
4751
4752      See the :term:`MACHINE` variable for additional information.
4753
4754   :term:`MODULE_TARBALL_NAME`
4755      The base name of the kernel module tarball. This variable is set in
4756      the ``meta/classes/kernel-artifact-names.bbclass`` file as follows::
4757
4758         MODULE_TARBALL_NAME ?= "${KERNEL_ARTIFACT_NAME}"
4759
4760      The value of the :term:`KERNEL_ARTIFACT_NAME` variable,
4761      which is set in the same file, has the following value::
4762
4763         KERNEL_ARTIFACT_NAME ?= "${PKGE}-${PKGV}-${PKGR}-${MACHINE}${IMAGE_VERSION_SUFFIX}"
4764
4765   :term:`MULTIMACH_TARGET_SYS`
4766      Uniquely identifies the type of the target system for which packages
4767      are being built. This variable allows output for different types of
4768      target systems to be put into different subdirectories of the same
4769      output directory.
4770
4771      The default value of this variable is::
4772
4773         ${PACKAGE_ARCH}${TARGET_VENDOR}-${TARGET_OS}
4774
4775      Some classes (e.g.
4776      :ref:`cross-canadian <ref-classes-cross-canadian>`) modify the
4777      :term:`MULTIMACH_TARGET_SYS` value.
4778
4779      See the :term:`STAMP` variable for an example. See the
4780      :term:`STAGING_DIR_TARGET` variable for more information.
4781
4782   :term:`NATIVELSBSTRING`
4783      A string identifying the host distribution. Strings consist of the
4784      host distributor ID followed by the release, as reported by the
4785      ``lsb_release`` tool or as read from ``/etc/lsb-release``. For
4786      example, when running a build on Ubuntu 12.10, the value is
4787      "Ubuntu-12.10". If this information is unable to be determined, the
4788      value resolves to "Unknown".
4789
4790      This variable is used by default to isolate native shared state
4791      packages for different distributions (e.g. to avoid problems with
4792      ``glibc`` version incompatibilities). Additionally, the variable is
4793      checked against
4794      :term:`SANITY_TESTED_DISTROS` if that
4795      variable is set.
4796
4797   :term:`NM`
4798      The minimal command and arguments to run ``nm``.
4799
4800   :term:`NO_GENERIC_LICENSE`
4801      Avoids QA errors when you use a non-common, non-CLOSED license in a
4802      recipe. There are packages, such as the linux-firmware package, with many
4803      licenses that are not in any way common. Also, new licenses are added
4804      occasionally to avoid introducing a lot of common license files,
4805      which are only applicable to a specific package.
4806      :term:`NO_GENERIC_LICENSE` is used to allow copying a license that does
4807      not exist in common licenses.
4808
4809      The following example shows how to add :term:`NO_GENERIC_LICENSE` to a
4810      recipe::
4811
4812         NO_GENERIC_LICENSE[license_name] = "license_file_in_fetched_source"
4813
4814      Here is an example that
4815      uses the ``LICENSE.Abilis.txt`` file as the license from the fetched
4816      source::
4817
4818         NO_GENERIC_LICENSE[Firmware-Abilis] = "LICENSE.Abilis.txt"
4819
4820   :term:`NO_RECOMMENDATIONS`
4821      Prevents installation of all "recommended-only" packages.
4822      Recommended-only packages are packages installed only through the
4823      :term:`RRECOMMENDS` variable). Setting the
4824      :term:`NO_RECOMMENDATIONS` variable to "1" turns this feature on::
4825
4826         NO_RECOMMENDATIONS = "1"
4827
4828      You can set this variable globally in your ``local.conf`` file or you
4829      can attach it to a specific image recipe by using the recipe name
4830      override::
4831
4832         NO_RECOMMENDATIONS:pn-target_image = "1"
4833
4834      It is important to realize that if you choose to not install packages
4835      using this variable and some other packages are dependent on them
4836      (i.e. listed in a recipe's :term:`RDEPENDS`
4837      variable), the OpenEmbedded build system ignores your request and
4838      will install the packages to avoid dependency errors.
4839
4840      .. note::
4841
4842         Some recommended packages might be required for certain system
4843         functionality, such as kernel modules. It is up to you to add
4844         packages with the :term:`IMAGE_INSTALL` variable.
4845
4846      This variable is only supported when using the IPK and RPM
4847      packaging backends. DEB is not supported.
4848
4849      See the :term:`BAD_RECOMMENDATIONS` and
4850      the :term:`PACKAGE_EXCLUDE` variables for
4851      related information.
4852
4853   :term:`NOAUTOPACKAGEDEBUG`
4854      Disables auto package from splitting ``.debug`` files. If a recipe
4855      requires ``FILES:${PN}-dbg`` to be set manually, the
4856      :term:`NOAUTOPACKAGEDEBUG` can be defined allowing you to define the
4857      content of the debug package. For example::
4858
4859         NOAUTOPACKAGEDEBUG = "1"
4860         FILES:${PN}-dev = "${includedir}/${QT_DIR_NAME}/Qt/*"
4861         FILES:${PN}-dbg = "/usr/src/debug/"
4862         FILES:${QT_BASE_NAME}-demos-doc = "${docdir}/${QT_DIR_NAME}/qch/qt.qch"
4863
4864   :term:`NON_MULTILIB_RECIPES`
4865      A list of recipes that should not be built for multilib. OE-Core's
4866      ``multilib.conf`` file defines a reasonable starting point for this
4867      list with::
4868
4869         NON_MULTILIB_RECIPES = "grub grub-efi make-mod-scripts ovmf u-boot"
4870
4871   :term:`OBJCOPY`
4872      The minimal command and arguments to run ``objcopy``.
4873
4874   :term:`OBJDUMP`
4875      The minimal command and arguments to run ``objdump``.
4876
4877   :term:`OE_BINCONFIG_EXTRA_MANGLE`
4878      When inheriting the :ref:`binconfig <ref-classes-binconfig>` class,
4879      this variable specifies additional arguments passed to the "sed"
4880      command. The sed command alters any paths in configuration scripts
4881      that have been set up during compilation. Inheriting this class
4882      results in all paths in these scripts being changed to point into the
4883      ``sysroots/`` directory so that all builds that use the script will
4884      use the correct directories for the cross compiling layout.
4885
4886      See the ``meta/classes/binconfig.bbclass`` in the
4887      :term:`Source Directory` for details on how this class
4888      applies these additional sed command arguments. For general
4889      information on the ``binconfig`` class, see the
4890      ":ref:`binconfig.bbclass <ref-classes-binconfig>`" section.
4891
4892   :term:`OE_IMPORTS`
4893      An internal variable used to tell the OpenEmbedded build system what
4894      Python modules to import for every Python function run by the system.
4895
4896      .. note::
4897
4898         Do not set this variable. It is for internal use only.
4899
4900   :term:`OE_INIT_ENV_SCRIPT`
4901      The name of the build environment setup script for the purposes of
4902      setting up the environment within the extensible SDK. The default
4903      value is "oe-init-build-env".
4904
4905      If you use a custom script to set up your build environment, set the
4906      :term:`OE_INIT_ENV_SCRIPT` variable to its name.
4907
4908   :term:`OE_TERMINAL`
4909      Controls how the OpenEmbedded build system spawns interactive
4910      terminals on the host development system (e.g. using the BitBake
4911      command with the ``-c devshell`` command-line option). For more
4912      information, see the ":ref:`dev-manual/common-tasks:using a development shell`" section in
4913      the Yocto Project Development Tasks Manual.
4914
4915      You can use the following values for the :term:`OE_TERMINAL` variable:
4916
4917      - auto
4918      - gnome
4919      - xfce
4920      - rxvt
4921      - screen
4922      - konsole
4923      - none
4924
4925   :term:`OEROOT`
4926      The directory from which the top-level build environment setup script
4927      is sourced. The Yocto Project provides a top-level build environment
4928      setup script: :ref:`structure-core-script`. When you run this
4929      script, the :term:`OEROOT` variable resolves to the directory that
4930      contains the script.
4931
4932      For additional information on how this variable is used, see the
4933      initialization script.
4934
4935   :term:`OLDEST_KERNEL`
4936      Declares the oldest version of the Linux kernel that the produced
4937      binaries must support. This variable is passed into the build of the
4938      Embedded GNU C Library (``glibc``).
4939
4940      The default for this variable comes from the
4941      ``meta/conf/bitbake.conf`` configuration file. You can override this
4942      default by setting the variable in a custom distribution
4943      configuration file.
4944
4945   :term:`OVERRIDES`
4946      A colon-separated list of overrides that currently apply. Overrides
4947      are a BitBake mechanism that allows variables to be selectively
4948      overridden at the end of parsing. The set of overrides in
4949      :term:`OVERRIDES` represents the "state" during building, which includes
4950      the current recipe being built, the machine for which it is being
4951      built, and so forth.
4952
4953      As an example, if the string "an-override" appears as an element in
4954      the colon-separated list in :term:`OVERRIDES`, then the following
4955      assignment will override ``FOO`` with the value "overridden" at the
4956      end of parsing::
4957
4958         FOO:an-override = "overridden"
4959
4960      See the
4961      ":ref:`bitbake:bitbake-user-manual/bitbake-user-manual-metadata:conditional syntax (overrides)`"
4962      section in the BitBake User Manual for more information on the
4963      overrides mechanism.
4964
4965      The default value of :term:`OVERRIDES` includes the values of the
4966      :term:`CLASSOVERRIDE`,
4967      :term:`MACHINEOVERRIDES`, and
4968      :term:`DISTROOVERRIDES` variables. Another
4969      important override included by default is ``pn-${PN}``. This override
4970      allows variables to be set for a single recipe within configuration
4971      (``.conf``) files. Here is an example::
4972
4973         FOO:pn-myrecipe = "myrecipe-specific value"
4974
4975      .. note::
4976
4977         An easy way to see what overrides apply is to search for :term:`OVERRIDES`
4978         in the output of the ``bitbake -e`` command. See the
4979         ":ref:`dev-manual/common-tasks:viewing variable values`" section in the Yocto
4980         Project Development Tasks Manual for more information.
4981
4982   :term:`P`
4983      The recipe name and version. :term:`P` is comprised of the following::
4984
4985         ${PN}-${PV}
4986
4987   :term:`PACKAGE_ADD_METADATA`
4988      This variable defines additional metadata to add to packages.
4989
4990      You may find you need to inject additional metadata into packages.
4991      This variable allows you to do that by setting the injected data as
4992      the value. Multiple fields can be added by splitting the content with
4993      the literal separator "\n".
4994
4995      The suffixes '_IPK', '_DEB', or '_RPM' can be applied to the variable
4996      to do package type specific settings. It can also be made package
4997      specific by using the package name as a suffix.
4998
4999      You can find out more about applying this variable in the
5000      ":ref:`dev-manual/common-tasks:adding custom metadata to packages`"
5001      section in the Yocto Project Development Tasks Manual.
5002
5003   :term:`PACKAGE_ARCH`
5004      The architecture of the resulting package or packages.
5005
5006      By default, the value of this variable is set to
5007      :term:`TUNE_PKGARCH` when building for the
5008      target, :term:`BUILD_ARCH` when building for the
5009      build host, and "${SDK_ARCH}-${SDKPKGSUFFIX}" when building for the
5010      SDK.
5011
5012      .. note::
5013
5014         See :term:`SDK_ARCH` for more information.
5015
5016      However, if your recipe's output packages are built specific to the
5017      target machine rather than generally for the architecture of the
5018      machine, you should set :term:`PACKAGE_ARCH` to the value of
5019      :term:`MACHINE_ARCH` in the recipe as follows::
5020
5021         PACKAGE_ARCH = "${MACHINE_ARCH}"
5022
5023   :term:`PACKAGE_ARCHS`
5024      Specifies a list of architectures compatible with the target machine.
5025      This variable is set automatically and should not normally be
5026      hand-edited. Entries are separated using spaces and listed in order
5027      of priority. The default value for :term:`PACKAGE_ARCHS` is "all any
5028      noarch ${PACKAGE_EXTRA_ARCHS} ${MACHINE_ARCH}".
5029
5030   :term:`PACKAGE_BEFORE_PN`
5031      Enables easily adding packages to :term:`PACKAGES` before ``${PN}`` so
5032      that those added packages can pick up files that would normally be
5033      included in the default package.
5034
5035   :term:`PACKAGE_CLASSES`
5036      This variable, which is set in the ``local.conf`` configuration file
5037      found in the ``conf`` folder of the
5038      :term:`Build Directory`, specifies the package manager the
5039      OpenEmbedded build system uses when packaging data.
5040
5041      You can provide one or more of the following arguments for the
5042      variable: PACKAGE_CLASSES ?= "package_rpm package_deb package_ipk
5043      package_tar"
5044
5045      .. note::
5046
5047         While it is a legal option, the ``package_tar``
5048         class has limited functionality due to no support for package
5049         dependencies by that backend. Therefore, it is recommended that
5050         you do not use it.
5051
5052      The build system uses only the first argument in the list as the
5053      package manager when creating your image or SDK. However, packages
5054      will be created using any additional packaging classes you specify.
5055      For example, if you use the following in your ``local.conf`` file::
5056
5057         PACKAGE_CLASSES ?= "package_ipk"
5058
5059      The OpenEmbedded build system uses
5060      the IPK package manager to create your image or SDK.
5061
5062      For information on packaging and build performance effects as a
5063      result of the package manager in use, see the
5064      ":ref:`package.bbclass <ref-classes-package>`" section.
5065
5066   :term:`PACKAGE_DEBUG_SPLIT_STYLE`
5067      Determines how to split up the binary and debug information when
5068      creating ``*-dbg`` packages to be used with the GNU Project Debugger
5069      (GDB).
5070
5071      With the :term:`PACKAGE_DEBUG_SPLIT_STYLE` variable, you can control
5072      where debug information, which can include or exclude source files,
5073      is stored:
5074
5075      -  ".debug": Debug symbol files are placed next to the binary in a
5076         ``.debug`` directory on the target. For example, if a binary is
5077         installed into ``/bin``, the corresponding debug symbol files are
5078         installed in ``/bin/.debug``. Source files are placed in
5079         ``/usr/src/debug``.
5080
5081      -  "debug-file-directory": Debug symbol files are placed under
5082         ``/usr/lib/debug`` on the target, and separated by the path from
5083         where the binary is installed. For example, if a binary is
5084         installed in ``/bin``, the corresponding debug symbols are
5085         installed in ``/usr/lib/debug/bin``. Source files are placed in
5086         ``/usr/src/debug``.
5087
5088      -  "debug-without-src": The same behavior as ".debug" previously
5089         described with the exception that no source files are installed.
5090
5091      -  "debug-with-srcpkg": The same behavior as ".debug" previously
5092         described with the exception that all source files are placed in a
5093         separate ``*-src`` pkg. This is the default behavior.
5094
5095      You can find out more about debugging using GDB by reading the
5096      ":ref:`dev-manual/common-tasks:debugging with the gnu project debugger (gdb) remotely`" section
5097      in the Yocto Project Development Tasks Manual.
5098
5099   :term:`PACKAGE_EXCLUDE_COMPLEMENTARY`
5100      Prevents specific packages from being installed when you are
5101      installing complementary packages.
5102
5103      You might find that you want to prevent installing certain packages
5104      when you are installing complementary packages. For example, if you
5105      are using :term:`IMAGE_FEATURES` to install
5106      ``dev-pkgs``, you might not want to install all packages from a
5107      particular multilib. If you find yourself in this situation, you can
5108      use the :term:`PACKAGE_EXCLUDE_COMPLEMENTARY` variable to specify regular
5109      expressions to match the packages you want to exclude.
5110
5111   :term:`PACKAGE_EXCLUDE`
5112      Lists packages that should not be installed into an image. For
5113      example::
5114
5115         PACKAGE_EXCLUDE = "package_name package_name package_name ..."
5116
5117      You can set this variable globally in your ``local.conf`` file or you
5118      can attach it to a specific image recipe by using the recipe name
5119      override::
5120
5121         PACKAGE_EXCLUDE:pn-target_image = "package_name"
5122
5123      If you choose to not install a package using this variable and some
5124      other package is dependent on it (i.e. listed in a recipe's
5125      :term:`RDEPENDS` variable), the OpenEmbedded build
5126      system generates a fatal installation error. Because the build system
5127      halts the process with a fatal error, you can use the variable with
5128      an iterative development process to remove specific components from a
5129      system.
5130
5131      This variable is supported only when using the IPK and RPM
5132      packaging backends. DEB is not supported.
5133
5134      See the :term:`NO_RECOMMENDATIONS` and the
5135      :term:`BAD_RECOMMENDATIONS` variables for
5136      related information.
5137
5138   :term:`PACKAGE_EXTRA_ARCHS`
5139      Specifies the list of architectures compatible with the device CPU.
5140      This variable is useful when you build for several different devices
5141      that use miscellaneous processors such as XScale and ARM926-EJS.
5142
5143   :term:`PACKAGE_FEED_ARCHS`
5144      Optionally specifies the package architectures used as part of the
5145      package feed URIs during the build. When used, the
5146      :term:`PACKAGE_FEED_ARCHS` variable is appended to the final package feed
5147      URI, which is constructed using the
5148      :term:`PACKAGE_FEED_URIS` and
5149      :term:`PACKAGE_FEED_BASE_PATHS`
5150      variables.
5151
5152      .. note::
5153
5154         You can use the :term:`PACKAGE_FEED_ARCHS`
5155         variable to whitelist specific package architectures. If you do
5156         not need to whitelist specific architectures, which is a common
5157         case, you can omit this variable. Omitting the variable results in
5158         all available architectures for the current machine being included
5159         into remote package feeds.
5160
5161      Consider the following example where the :term:`PACKAGE_FEED_URIS`,
5162      :term:`PACKAGE_FEED_BASE_PATHS`, and :term:`PACKAGE_FEED_ARCHS` variables are
5163      defined in your ``local.conf`` file::
5164
5165         PACKAGE_FEED_URIS = "https://example.com/packagerepos/release \
5166                              https://example.com/packagerepos/updates"
5167         PACKAGE_FEED_BASE_PATHS = "rpm rpm-dev"
5168         PACKAGE_FEED_ARCHS = "all core2-64"
5169
5170      Given these settings, the resulting package feeds are as follows:
5171
5172      .. code-block:: none
5173
5174         https://example.com/packagerepos/release/rpm/all
5175         https://example.com/packagerepos/release/rpm/core2-64
5176         https://example.com/packagerepos/release/rpm-dev/all
5177         https://example.com/packagerepos/release/rpm-dev/core2-64
5178         https://example.com/packagerepos/updates/rpm/all
5179         https://example.com/packagerepos/updates/rpm/core2-64
5180         https://example.com/packagerepos/updates/rpm-dev/all
5181         https://example.com/packagerepos/updates/rpm-dev/core2-64
5182
5183   :term:`PACKAGE_FEED_BASE_PATHS`
5184      Specifies the base path used when constructing package feed URIs. The
5185      :term:`PACKAGE_FEED_BASE_PATHS` variable makes up the middle portion of a
5186      package feed URI used by the OpenEmbedded build system. The base path
5187      lies between the :term:`PACKAGE_FEED_URIS`
5188      and :term:`PACKAGE_FEED_ARCHS` variables.
5189
5190      Consider the following example where the :term:`PACKAGE_FEED_URIS`,
5191      :term:`PACKAGE_FEED_BASE_PATHS`, and :term:`PACKAGE_FEED_ARCHS` variables are
5192      defined in your ``local.conf`` file::
5193
5194         PACKAGE_FEED_URIS = "https://example.com/packagerepos/release \
5195                              https://example.com/packagerepos/updates"
5196         PACKAGE_FEED_BASE_PATHS = "rpm rpm-dev"
5197         PACKAGE_FEED_ARCHS = "all core2-64"
5198
5199      Given these settings, the resulting package feeds are as follows:
5200
5201      .. code-block:: none
5202
5203         https://example.com/packagerepos/release/rpm/all
5204         https://example.com/packagerepos/release/rpm/core2-64
5205         https://example.com/packagerepos/release/rpm-dev/all
5206         https://example.com/packagerepos/release/rpm-dev/core2-64
5207         https://example.com/packagerepos/updates/rpm/all
5208         https://example.com/packagerepos/updates/rpm/core2-64
5209         https://example.com/packagerepos/updates/rpm-dev/all
5210         https://example.com/packagerepos/updates/rpm-dev/core2-64
5211
5212   :term:`PACKAGE_FEED_URIS`
5213      Specifies the front portion of the package feed URI used by the
5214      OpenEmbedded build system. Each final package feed URI is comprised
5215      of :term:`PACKAGE_FEED_URIS`,
5216      :term:`PACKAGE_FEED_BASE_PATHS`, and
5217      :term:`PACKAGE_FEED_ARCHS` variables.
5218
5219      Consider the following example where the :term:`PACKAGE_FEED_URIS`,
5220      :term:`PACKAGE_FEED_BASE_PATHS`, and :term:`PACKAGE_FEED_ARCHS` variables are
5221      defined in your ``local.conf`` file::
5222
5223         PACKAGE_FEED_URIS = "https://example.com/packagerepos/release \
5224                              https://example.com/packagerepos/updates"
5225         PACKAGE_FEED_BASE_PATHS = "rpm rpm-dev"
5226         PACKAGE_FEED_ARCHS = "all core2-64"
5227
5228      Given these settings, the resulting package feeds are as follows:
5229
5230      .. code-block:: none
5231
5232         https://example.com/packagerepos/release/rpm/all
5233         https://example.com/packagerepos/release/rpm/core2-64
5234         https://example.com/packagerepos/release/rpm-dev/all
5235         https://example.com/packagerepos/release/rpm-dev/core2-64
5236         https://example.com/packagerepos/updates/rpm/all
5237         https://example.com/packagerepos/updates/rpm/core2-64
5238         https://example.com/packagerepos/updates/rpm-dev/all
5239         https://example.com/packagerepos/updates/rpm-dev/core2-64
5240
5241   :term:`PACKAGE_INSTALL`
5242      The final list of packages passed to the package manager for
5243      installation into the image.
5244
5245      Because the package manager controls actual installation of all
5246      packages, the list of packages passed using :term:`PACKAGE_INSTALL` is
5247      not the final list of packages that are actually installed. This
5248      variable is internal to the image construction code. Consequently, in
5249      general, you should use the
5250      :term:`IMAGE_INSTALL` variable to specify
5251      packages for installation. The exception to this is when working with
5252      the :ref:`core-image-minimal-initramfs <ref-manual/images:images>`
5253      image. When working with an initial RAM filesystem (initramfs) image,
5254      use the :term:`PACKAGE_INSTALL` variable. For information on creating an
5255      initramfs, see the ":ref:`dev-manual/common-tasks:building an initial ram filesystem (initramfs) image`" section
5256      in the Yocto Project Development Tasks Manual.
5257
5258   :term:`PACKAGE_INSTALL_ATTEMPTONLY`
5259      Specifies a list of packages the OpenEmbedded build system attempts
5260      to install when creating an image. If a listed package fails to
5261      install, the build system does not generate an error. This variable
5262      is generally not user-defined.
5263
5264   :term:`PACKAGE_PREPROCESS_FUNCS`
5265      Specifies a list of functions run to pre-process the
5266      :term:`PKGD` directory prior to splitting the files out
5267      to individual packages.
5268
5269   :term:`PACKAGE_WRITE_DEPS`
5270      Specifies a list of dependencies for post-installation and
5271      pre-installation scripts on native/cross tools. If your
5272      post-installation or pre-installation script can execute at rootfs
5273      creation time rather than on the target but depends on a native tool
5274      in order to execute, you need to list the tools in
5275      :term:`PACKAGE_WRITE_DEPS`.
5276
5277      For information on running post-installation scripts, see the
5278      ":ref:`dev-manual/common-tasks:post-installation scripts`"
5279      section in the Yocto Project Development Tasks Manual.
5280
5281   :term:`PACKAGECONFIG`
5282      This variable provides a means of enabling or disabling features of a
5283      recipe on a per-recipe basis. :term:`PACKAGECONFIG` blocks are defined in
5284      recipes when you specify features and then arguments that define
5285      feature behaviors. Here is the basic block structure (broken over
5286      multiple lines for readability)::
5287
5288         PACKAGECONFIG ??= "f1 f2 f3 ..."
5289         PACKAGECONFIG[f1] = "\
5290             --with-f1, \
5291             --without-f1, \
5292             build-deps-for-f1, \
5293             runtime-deps-for-f1, \
5294             runtime-recommends-for-f1, \
5295             packageconfig-conflicts-for-f1"
5296         PACKAGECONFIG[f2] = "\
5297              ... and so on and so on ...
5298
5299      The :term:`PACKAGECONFIG` variable itself specifies a space-separated
5300      list of the features to enable. Following the features, you can
5301      determine the behavior of each feature by providing up to six
5302      order-dependent arguments, which are separated by commas. You can
5303      omit any argument you like but must retain the separating commas. The
5304      order is important and specifies the following:
5305
5306      1. Extra arguments that should be added to the configure script
5307         argument list (:term:`EXTRA_OECONF` or
5308         :term:`PACKAGECONFIG_CONFARGS`) if
5309         the feature is enabled.
5310
5311      2. Extra arguments that should be added to :term:`EXTRA_OECONF` or
5312         :term:`PACKAGECONFIG_CONFARGS` if the feature is disabled.
5313
5314      3. Additional build dependencies (:term:`DEPENDS`)
5315         that should be added if the feature is enabled.
5316
5317      4. Additional runtime dependencies (:term:`RDEPENDS`)
5318         that should be added if the feature is enabled.
5319
5320      5. Additional runtime recommendations
5321         (:term:`RRECOMMENDS`) that should be added if
5322         the feature is enabled.
5323
5324      6. Any conflicting (that is, mutually exclusive) :term:`PACKAGECONFIG`
5325         settings for this feature.
5326
5327      Consider the following :term:`PACKAGECONFIG` block taken from the
5328      ``librsvg`` recipe. In this example the feature is ``gtk``, which has
5329      three arguments that determine the feature's behavior.
5330      ::
5331
5332         PACKAGECONFIG[gtk] = "--with-gtk3,--without-gtk3,gtk+3"
5333
5334      The
5335      ``--with-gtk3`` and ``gtk+3`` arguments apply only if the feature is
5336      enabled. In this case, ``--with-gtk3`` is added to the configure
5337      script argument list and ``gtk+3`` is added to :term:`DEPENDS`. On the
5338      other hand, if the feature is disabled say through a ``.bbappend``
5339      file in another layer, then the second argument ``--without-gtk3`` is
5340      added to the configure script instead.
5341
5342      The basic :term:`PACKAGECONFIG` structure previously described holds true
5343      regardless of whether you are creating a block or changing a block.
5344      When creating a block, use the structure inside your recipe.
5345
5346      If you want to change an existing :term:`PACKAGECONFIG` block, you can do
5347      so one of two ways:
5348
5349      -  *Append file:* Create an append file named
5350         recipename\ ``.bbappend`` in your layer and override the value of
5351         :term:`PACKAGECONFIG`. You can either completely override the
5352         variable::
5353
5354            PACKAGECONFIG = "f4 f5"
5355
5356         Or, you can just append the variable::
5357
5358            PACKAGECONFIG:append = " f4"
5359
5360      -  *Configuration file:* This method is identical to changing the
5361         block through an append file except you edit your ``local.conf``
5362         or ``mydistro.conf`` file. As with append files previously
5363         described, you can either completely override the variable::
5364
5365            PACKAGECONFIG:pn-recipename = "f4 f5"
5366
5367         Or, you can just amend the variable::
5368
5369            PACKAGECONFIG:append:pn-recipename = " f4"
5370
5371   :term:`PACKAGECONFIG_CONFARGS`
5372      A space-separated list of configuration options generated from the
5373      :term:`PACKAGECONFIG` setting.
5374
5375      Classes such as :ref:`autotools <ref-classes-autotools>` and
5376      :ref:`cmake <ref-classes-cmake>` use :term:`PACKAGECONFIG_CONFARGS` to
5377      pass :term:`PACKAGECONFIG` options to ``configure`` and ``cmake``,
5378      respectively. If you are using :term:`PACKAGECONFIG` but not a class that
5379      handles the ``do_configure`` task, then you need to use
5380      :term:`PACKAGECONFIG_CONFARGS` appropriately.
5381
5382   :term:`PACKAGEGROUP_DISABLE_COMPLEMENTARY`
5383      For recipes inheriting the
5384      :ref:`packagegroup <ref-classes-packagegroup>` class, setting
5385      :term:`PACKAGEGROUP_DISABLE_COMPLEMENTARY` to "1" specifies that the
5386      normal complementary packages (i.e. ``-dev``, ``-dbg``, and so forth)
5387      should not be automatically created by the ``packagegroup`` recipe,
5388      which is the default behavior.
5389
5390   :term:`PACKAGES`
5391      The list of packages the recipe creates. The default value is the
5392      following::
5393
5394         ${PN}-dbg ${PN}-staticdev ${PN}-dev ${PN}-doc ${PN}-locale ${PACKAGE_BEFORE_PN} ${PN}
5395
5396      During packaging, the :ref:`ref-tasks-package` task
5397      goes through :term:`PACKAGES` and uses the :term:`FILES`
5398      variable corresponding to each package to assign files to the
5399      package. If a file matches the :term:`FILES` variable for more than one
5400      package in :term:`PACKAGES`, it will be assigned to the earliest
5401      (leftmost) package.
5402
5403      Packages in the variable's list that are empty (i.e. where none of
5404      the patterns in ``FILES:``\ pkg match any files installed by the
5405      :ref:`ref-tasks-install` task) are not generated,
5406      unless generation is forced through the
5407      :term:`ALLOW_EMPTY` variable.
5408
5409   :term:`PACKAGES_DYNAMIC`
5410      A promise that your recipe satisfies runtime dependencies for
5411      optional modules that are found in other recipes.
5412      :term:`PACKAGES_DYNAMIC` does not actually satisfy the dependencies, it
5413      only states that they should be satisfied. For example, if a hard,
5414      runtime dependency (:term:`RDEPENDS`) of another
5415      package is satisfied at build time through the :term:`PACKAGES_DYNAMIC`
5416      variable, but a package with the module name is never actually
5417      produced, then the other package will be broken. Thus, if you attempt
5418      to include that package in an image, you will get a dependency
5419      failure from the packaging system during the
5420      :ref:`ref-tasks-rootfs` task.
5421
5422      Typically, if there is a chance that such a situation can occur and
5423      the package that is not created is valid without the dependency being
5424      satisfied, then you should use :term:`RRECOMMENDS`
5425      (a soft runtime dependency) instead of :term:`RDEPENDS`.
5426
5427      For an example of how to use the :term:`PACKAGES_DYNAMIC` variable when
5428      you are splitting packages, see the
5429      ":ref:`dev-manual/common-tasks:handling optional module packaging`"
5430      section in the Yocto Project Development Tasks Manual.
5431
5432   :term:`PACKAGESPLITFUNCS`
5433      Specifies a list of functions run to perform additional splitting of
5434      files into individual packages. Recipes can either prepend to this
5435      variable or prepend to the ``populate_packages`` function in order to
5436      perform additional package splitting. In either case, the function
5437      should set :term:`PACKAGES`,
5438      :term:`FILES`, :term:`RDEPENDS` and
5439      other packaging variables appropriately in order to perform the
5440      desired splitting.
5441
5442   :term:`PARALLEL_MAKE`
5443      Extra options passed to the ``make`` command during the
5444      :ref:`ref-tasks-compile` task in order to specify
5445      parallel compilation on the local build host. This variable is
5446      usually in the form "-j x", where x represents the maximum number of
5447      parallel threads ``make`` can run.
5448
5449      .. note::
5450
5451         In order for :term:`PARALLEL_MAKE` to be effective, ``make`` must be
5452         called with ``${``\ :term:`EXTRA_OEMAKE`\ ``}``. An easy way to ensure
5453         this is to use the ``oe_runmake`` function.
5454
5455      By default, the OpenEmbedded build system automatically sets this
5456      variable to be equal to the number of cores the build system uses.
5457
5458      .. note::
5459
5460         If the software being built experiences dependency issues during
5461         the ``do_compile`` task that result in race conditions, you can clear
5462         the :term:`PARALLEL_MAKE` variable within the recipe as a workaround. For
5463         information on addressing race conditions, see the
5464         ":ref:`dev-manual/common-tasks:debugging parallel make races`"
5465         section in the Yocto Project Development Tasks Manual.
5466
5467      For single socket systems (i.e. one CPU), you should not have to
5468      override this variable to gain optimal parallelism during builds.
5469      However, if you have very large systems that employ multiple physical
5470      CPUs, you might want to make sure the :term:`PARALLEL_MAKE` variable is
5471      not set higher than "-j 20".
5472
5473      For more information on speeding up builds, see the
5474      ":ref:`dev-manual/common-tasks:speeding up a build`"
5475      section in the Yocto Project Development Tasks Manual.
5476
5477   :term:`PARALLEL_MAKEINST`
5478      Extra options passed to the ``make install`` command during the
5479      :ref:`ref-tasks-install` task in order to specify
5480      parallel installation. This variable defaults to the value of
5481      :term:`PARALLEL_MAKE`.
5482
5483      .. note::
5484
5485         In order for :term:`PARALLEL_MAKEINST` to be effective, ``make`` must
5486         be called with
5487         ``${``\ :term:`EXTRA_OEMAKE`\ ``}``. An easy
5488         way to ensure this is to use the ``oe_runmake`` function.
5489
5490         If the software being built experiences dependency issues during
5491         the ``do_install`` task that result in race conditions, you can
5492         clear the :term:`PARALLEL_MAKEINST` variable within the recipe as a
5493         workaround. For information on addressing race conditions, see the
5494         ":ref:`dev-manual/common-tasks:debugging parallel make races`"
5495         section in the Yocto Project Development Tasks Manual.
5496
5497   :term:`PATCHRESOLVE`
5498      Determines the action to take when a patch fails. You can set this
5499      variable to one of two values: "noop" and "user".
5500
5501      The default value of "noop" causes the build to simply fail when the
5502      OpenEmbedded build system cannot successfully apply a patch. Setting
5503      the value to "user" causes the build system to launch a shell and
5504      places you in the right location so that you can manually resolve the
5505      conflicts.
5506
5507      Set this variable in your ``local.conf`` file.
5508
5509   :term:`PATCHTOOL`
5510      Specifies the utility used to apply patches for a recipe during the
5511      :ref:`ref-tasks-patch` task. You can specify one of
5512      three utilities: "patch", "quilt", or "git". The default utility used
5513      is "quilt" except for the quilt-native recipe itself. Because the
5514      quilt tool is not available at the time quilt-native is being
5515      patched, it uses "patch".
5516
5517      If you wish to use an alternative patching tool, set the variable in
5518      the recipe using one of the following::
5519
5520         PATCHTOOL = "patch"
5521         PATCHTOOL = "quilt"
5522         PATCHTOOL = "git"
5523
5524   :term:`PE`
5525      The epoch of the recipe. By default, this variable is unset. The
5526      variable is used to make upgrades possible when the versioning scheme
5527      changes in some backwards incompatible way.
5528
5529      :term:`PE` is the default value of the :term:`PKGE` variable.
5530
5531   :term:`PF`
5532      Specifies the recipe or package name and includes all version and
5533      revision numbers (i.e. ``glibc-2.13-r20+svnr15508/`` and
5534      ``bash-4.2-r1/``). This variable is comprised of the following:
5535      ${:term:`PN`}-${:term:`EXTENDPE`}${:term:`PV`}-${:term:`PR`}
5536
5537   :term:`PIXBUF_PACKAGES`
5538      When inheriting the :ref:`pixbufcache <ref-classes-pixbufcache>`
5539      class, this variable identifies packages that contain the pixbuf
5540      loaders used with ``gdk-pixbuf``. By default, the ``pixbufcache``
5541      class assumes that the loaders are in the recipe's main package (i.e.
5542      ``${``\ :term:`PN`\ ``}``). Use this variable if the
5543      loaders you need are in a package other than that main package.
5544
5545   :term:`PKG`
5546      The name of the resulting package created by the OpenEmbedded build
5547      system.
5548
5549      .. note::
5550
5551         When using the :term:`PKG` variable, you must use a package name override.
5552
5553      For example, when the :ref:`debian <ref-classes-debian>` class
5554      renames the output package, it does so by setting
5555      ``PKG:packagename``.
5556
5557   :term:`PKG_CONFIG_PATH`
5558      The path to ``pkg-config`` files for the current build context.
5559      ``pkg-config`` reads this variable from the environment.
5560
5561   :term:`PKGD`
5562      Points to the destination directory for files to be packaged before
5563      they are split into individual packages. This directory defaults to
5564      the following::
5565
5566         ${WORKDIR}/package
5567
5568      Do not change this default.
5569
5570   :term:`PKGDATA_DIR`
5571      Points to a shared, global-state directory that holds data generated
5572      during the packaging process. During the packaging process, the
5573      :ref:`ref-tasks-packagedata` task packages data
5574      for each recipe and installs it into this temporary, shared area.
5575      This directory defaults to the following, which you should not
5576      change::
5577
5578         ${STAGING_DIR_HOST}/pkgdata
5579
5580      For examples of how this data is used, see the
5581      ":ref:`overview-manual/concepts:automatically added runtime dependencies`"
5582      section in the Yocto Project Overview and Concepts Manual and the
5583      ":ref:`dev-manual/common-tasks:viewing package information with \`\`oe-pkgdata-util\`\``"
5584      section in the Yocto Project Development Tasks Manual. For more
5585      information on the shared, global-state directory, see
5586      :term:`STAGING_DIR_HOST`.
5587
5588   :term:`PKGDEST`
5589      Points to the parent directory for files to be packaged after they
5590      have been split into individual packages. This directory defaults to
5591      the following::
5592
5593         ${WORKDIR}/packages-split
5594
5595      Under this directory, the build system creates directories for each
5596      package specified in :term:`PACKAGES`. Do not change
5597      this default.
5598
5599   :term:`PKGDESTWORK`
5600      Points to a temporary work area where the
5601      :ref:`ref-tasks-package` task saves package metadata.
5602      The :term:`PKGDESTWORK` location defaults to the following::
5603
5604         ${WORKDIR}/pkgdata
5605
5606      Do not change this default.
5607
5608      The :ref:`ref-tasks-packagedata` task copies the
5609      package metadata from :term:`PKGDESTWORK` to
5610      :term:`PKGDATA_DIR` to make it available globally.
5611
5612   :term:`PKGE`
5613      The epoch of the package(s) built by the recipe. By default, :term:`PKGE`
5614      is set to :term:`PE`.
5615
5616   :term:`PKGR`
5617      The revision of the package(s) built by the recipe. By default,
5618      :term:`PKGR` is set to :term:`PR`.
5619
5620   :term:`PKGV`
5621      The version of the package(s) built by the recipe. By default,
5622      :term:`PKGV` is set to :term:`PV`.
5623
5624   :term:`PN`
5625      This variable can have two separate functions depending on the
5626      context: a recipe name or a resulting package name.
5627
5628      :term:`PN` refers to a recipe name in the context of a file used by the
5629      OpenEmbedded build system as input to create a package. The name is
5630      normally extracted from the recipe file name. For example, if the
5631      recipe is named ``expat_2.0.1.bb``, then the default value of :term:`PN`
5632      will be "expat".
5633
5634      The variable refers to a package name in the context of a file
5635      created or produced by the OpenEmbedded build system.
5636
5637      If applicable, the :term:`PN` variable also contains any special suffix
5638      or prefix. For example, using ``bash`` to build packages for the
5639      native machine, :term:`PN` is ``bash-native``. Using ``bash`` to build
5640      packages for the target and for Multilib, :term:`PN` would be ``bash``
5641      and ``lib64-bash``, respectively.
5642
5643   :term:`PNBLACKLIST`
5644      Lists recipes you do not want the OpenEmbedded build system to build.
5645      This variable works in conjunction with the
5646      :ref:`blacklist <ref-classes-blacklist>` class, which is inherited
5647      globally.
5648
5649      To prevent a recipe from being built, use the :term:`PNBLACKLIST`
5650      variable in your ``local.conf`` file. Here is an example that
5651      prevents ``myrecipe`` from being built::
5652
5653         PNBLACKLIST[myrecipe] = "Not supported by our organization."
5654
5655   :term:`POPULATE_SDK_POST_HOST_COMMAND`
5656      Specifies a list of functions to call once the OpenEmbedded build
5657      system has created the host part of the SDK. You can specify
5658      functions separated by semicolons::
5659
5660          POPULATE_SDK_POST_HOST_COMMAND += "function; ... "
5661
5662      If you need to pass the SDK path to a command within a function, you
5663      can use ``${SDK_DIR}``, which points to the parent directory used by
5664      the OpenEmbedded build system when creating SDK output. See the
5665      :term:`SDK_DIR` variable for more information.
5666
5667   :term:`POPULATE_SDK_POST_TARGET_COMMAND`
5668      Specifies a list of functions to call once the OpenEmbedded build
5669      system has created the target part of the SDK. You can specify
5670      functions separated by semicolons::
5671
5672         POPULATE_SDK_POST_TARGET_COMMAND += "function; ... "
5673
5674      If you need to pass the SDK path to a command within a function, you
5675      can use ``${SDK_DIR}``, which points to the parent directory used by
5676      the OpenEmbedded build system when creating SDK output. See the
5677      :term:`SDK_DIR` variable for more information.
5678
5679   :term:`PR`
5680      The revision of the recipe. The default value for this variable is
5681      "r0". Subsequent revisions of the recipe conventionally have the
5682      values "r1", "r2", and so forth. When :term:`PV` increases,
5683      :term:`PR` is conventionally reset to "r0".
5684
5685      .. note::
5686
5687         The OpenEmbedded build system does not need the aid of :term:`PR`
5688         to know when to rebuild a recipe. The build system uses the task
5689         :ref:`input checksums <overview-manual/concepts:checksums (signatures)>` along with the
5690         :ref:`stamp <structure-build-tmp-stamps>` and
5691         :ref:`overview-manual/concepts:shared state cache`
5692         mechanisms.
5693
5694      The :term:`PR` variable primarily becomes significant when a package
5695      manager dynamically installs packages on an already built image. In
5696      this case, :term:`PR`, which is the default value of
5697      :term:`PKGR`, helps the package manager distinguish which
5698      package is the most recent one in cases where many packages have the
5699      same :term:`PV` (i.e. :term:`PKGV`). A component having many packages with
5700      the same :term:`PV` usually means that the packages all install the same
5701      upstream version, but with later (:term:`PR`) version packages including
5702      packaging fixes.
5703
5704      .. note::
5705
5706         :term:`PR` does not need to be increased for changes that do not change the
5707         package contents or metadata.
5708
5709      Because manually managing :term:`PR` can be cumbersome and error-prone,
5710      an automated solution exists. See the
5711      ":ref:`dev-manual/common-tasks:working with a pr service`" section
5712      in the Yocto Project Development Tasks Manual for more information.
5713
5714   :term:`PREFERRED_PROVIDER`
5715      If multiple recipes provide the same item, this variable determines
5716      which recipe is preferred and thus provides the item (i.e. the
5717      preferred provider). You should always suffix this variable with the
5718      name of the provided item. And, you should define the variable using
5719      the preferred recipe's name (:term:`PN`). Here is a common
5720      example::
5721
5722         PREFERRED_PROVIDER_virtual/kernel ?= "linux-yocto"
5723
5724      In the previous example, multiple recipes are providing "virtual/kernel".
5725      The :term:`PREFERRED_PROVIDER` variable is set with the name (:term:`PN`) of
5726      the recipe you prefer to provide "virtual/kernel".
5727
5728      Following are more examples::
5729
5730         PREFERRED_PROVIDER_virtual/xserver = "xserver-xf86"
5731         PREFERRED_PROVIDER_virtual/libgl ?= "mesa"
5732
5733      For more
5734      information, see the ":ref:`dev-manual/common-tasks:using virtual providers`"
5735      section in the Yocto Project Development Tasks Manual.
5736
5737      .. note::
5738
5739         If you use a ``virtual/\*`` item with :term:`PREFERRED_PROVIDER`, then any
5740         recipe that :term:`PROVIDES` that item but is not selected (defined)
5741         by :term:`PREFERRED_PROVIDER` is prevented from building, which is usually
5742         desirable since this mechanism is designed to select between mutually
5743         exclusive alternative providers.
5744
5745   :term:`PREFERRED_VERSION`
5746      If there are multiple versions of a recipe available, this variable
5747      determines which version should be given preference. You must always
5748      suffix the variable with the :term:`PN` you want to select (`python` in
5749      the first example below), and you should specify the :term:`PV`
5750      accordingly (`3.4.0` in the example).
5751
5752      The :term:`PREFERRED_VERSION` variable supports limited wildcard use
5753      through the "``%``" character. You can use the character to match any
5754      number of characters, which can be useful when specifying versions
5755      that contain long revision numbers that potentially change. Here are
5756      two examples::
5757
5758         PREFERRED_VERSION_python = "3.4.0"
5759         PREFERRED_VERSION_linux-yocto = "5.0%"
5760
5761      .. note::
5762
5763         The use of the "%" character is limited in that it only works at the end of the
5764         string. You cannot use the wildcard character in any other
5765         location of the string.
5766
5767      The specified version is matched against :term:`PV`, which
5768      does not necessarily match the version part of the recipe's filename.
5769      For example, consider two recipes ``foo_1.2.bb`` and ``foo_git.bb``
5770      where ``foo_git.bb`` contains the following assignment::
5771
5772         PV = "1.1+git${SRCPV}"
5773
5774      In this case, the correct way to select
5775      ``foo_git.bb`` is by using an assignment such as the following::
5776
5777         PREFERRED_VERSION_foo = "1.1+git%"
5778
5779      Compare that previous example
5780      against the following incorrect example, which does not work::
5781
5782         PREFERRED_VERSION_foo = "git"
5783
5784      Sometimes the :term:`PREFERRED_VERSION` variable can be set by
5785      configuration files in a way that is hard to change. You can use
5786      :term:`OVERRIDES` to set a machine-specific
5787      override. Here is an example::
5788
5789         PREFERRED_VERSION_linux-yocto:qemux86 = "5.0%"
5790
5791      Although not recommended, worst case, you can also use the
5792      "forcevariable" override, which is the strongest override possible.
5793      Here is an example::
5794
5795         PREFERRED_VERSION_linux-yocto:forcevariable = "5.0%"
5796
5797      .. note::
5798
5799         The ``:forcevariable`` override is not handled specially. This override
5800         only works because the default value of :term:`OVERRIDES` includes "forcevariable".
5801
5802      If a recipe with the specified version is not available, a warning
5803      message will be shown. See :term:`REQUIRED_VERSION` if you want this
5804      to be an error instead.
5805
5806   :term:`PREMIRRORS`
5807      Specifies additional paths from which the OpenEmbedded build system
5808      gets source code. When the build system searches for source code, it
5809      first tries the local download directory. If that location fails, the
5810      build system tries locations defined by :term:`PREMIRRORS`, the upstream
5811      source, and then locations specified by
5812      :term:`MIRRORS` in that order.
5813
5814      Assuming your distribution (:term:`DISTRO`) is "poky",
5815      the default value for :term:`PREMIRRORS` is defined in the
5816      ``conf/distro/poky.conf`` file in the ``meta-poky`` Git repository.
5817
5818      Typically, you could add a specific server for the build system to
5819      attempt before any others by adding something like the following to
5820      the ``local.conf`` configuration file in the
5821      :term:`Build Directory`::
5822
5823         PREMIRRORS:prepend = "\
5824             git://.*/.* http://www.yoctoproject.org/sources/ \n \
5825             ftp://.*/.* http://www.yoctoproject.org/sources/ \n \
5826             http://.*/.* http://www.yoctoproject.org/sources/ \n \
5827             https://.*/.* http://www.yoctoproject.org/sources/ \n"
5828
5829      These changes cause the
5830      build system to intercept Git, FTP, HTTP, and HTTPS requests and
5831      direct them to the ``http://`` sources mirror. You can use
5832      ``file://`` URLs to point to local directories or network shares as
5833      well.
5834
5835   :term:`PRIORITY`
5836      Indicates the importance of a package.
5837
5838      :term:`PRIORITY` is considered to be part of the distribution policy
5839      because the importance of any given recipe depends on the purpose for
5840      which the distribution is being produced. Thus, :term:`PRIORITY` is not
5841      normally set within recipes.
5842
5843      You can set :term:`PRIORITY` to "required", "standard", "extra", and
5844      "optional", which is the default.
5845
5846   :term:`PRIVATE_LIBS`
5847      Specifies libraries installed within a recipe that should be ignored
5848      by the OpenEmbedded build system's shared library resolver. This
5849      variable is typically used when software being built by a recipe has
5850      its own private versions of a library normally provided by another
5851      recipe. In this case, you would not want the package containing the
5852      private libraries to be set as a dependency on other unrelated
5853      packages that should instead depend on the package providing the
5854      standard version of the library.
5855
5856      Libraries specified in this variable should be specified by their
5857      file name. For example, from the Firefox recipe in meta-browser::
5858
5859         PRIVATE_LIBS = "libmozjs.so \
5860                         libxpcom.so \
5861                         libnspr4.so \
5862                         libxul.so \
5863                         libmozalloc.so \
5864                         libplc4.so \
5865                         libplds4.so"
5866
5867      For more information, see the
5868      ":ref:`overview-manual/concepts:automatically added runtime dependencies`"
5869      section in the Yocto Project Overview and Concepts Manual.
5870
5871   :term:`PROVIDES`
5872      A list of aliases by which a particular recipe can be known. By
5873      default, a recipe's own :term:`PN` is implicitly already in its
5874      :term:`PROVIDES` list and therefore does not need to mention that it
5875      provides itself. If a recipe uses :term:`PROVIDES`, the additional
5876      aliases are synonyms for the recipe and can be useful for satisfying
5877      dependencies of other recipes during the build as specified by
5878      :term:`DEPENDS`.
5879
5880      Consider the following example :term:`PROVIDES` statement from the recipe
5881      file ``eudev_3.2.9.bb``::
5882
5883         PROVIDES += "udev"
5884
5885      The :term:`PROVIDES` statement
5886      results in the "eudev" recipe also being available as simply "udev".
5887
5888      .. note::
5889
5890         A recipe's own recipe name (:term:`PN`) is always implicitly prepended
5891         to `PROVIDES`, so while using "+=" in the above example may not be
5892         strictly necessary it is recommended to avoid confusion.
5893
5894      In addition to providing recipes under alternate names, the
5895      :term:`PROVIDES` mechanism is also used to implement virtual targets. A
5896      virtual target is a name that corresponds to some particular
5897      functionality (e.g. a Linux kernel). Recipes that provide the
5898      functionality in question list the virtual target in :term:`PROVIDES`.
5899      Recipes that depend on the functionality in question can include the
5900      virtual target in :term:`DEPENDS` to leave the choice of provider open.
5901
5902      Conventionally, virtual targets have names on the form
5903      "virtual/function" (e.g. "virtual/kernel"). The slash is simply part
5904      of the name and has no syntactical significance.
5905
5906      The :term:`PREFERRED_PROVIDER` variable is
5907      used to select which particular recipe provides a virtual target.
5908
5909      .. note::
5910
5911         A corresponding mechanism for virtual runtime dependencies
5912         (packages) exists. However, the mechanism does not depend on any
5913         special functionality beyond ordinary variable assignments. For
5914         example, ``VIRTUAL-RUNTIME_dev_manager`` refers to the package of
5915         the component that manages the ``/dev`` directory.
5916
5917         Setting the "preferred provider" for runtime dependencies is as
5918         simple as using the following assignment in a configuration file::
5919
5920                 VIRTUAL-RUNTIME_dev_manager = "udev"
5921
5922
5923   :term:`PRSERV_HOST`
5924      The network based :term:`PR` service host and port.
5925
5926      The ``conf/local.conf.sample.extended`` configuration file in the
5927      :term:`Source Directory` shows how the
5928      :term:`PRSERV_HOST` variable is set::
5929
5930         PRSERV_HOST = "localhost:0"
5931
5932      You must
5933      set the variable if you want to automatically start a local :ref:`PR
5934      service <dev-manual/common-tasks:working with a pr service>`. You can
5935      set :term:`PRSERV_HOST` to other values to use a remote PR service.
5936
5937
5938   :term:`PSEUDO_IGNORE_PATHS`
5939      A comma-separated (without spaces) list of path prefixes that should be ignored
5940      by pseudo when monitoring and recording file operations, in order to avoid
5941      problems with files being written to outside of the pseudo context and
5942      reduce pseudo's overhead. A path is ignored if it matches any prefix in the list
5943      and can include partial directory (or file) names.
5944
5945
5946   :term:`PTEST_ENABLED`
5947      Specifies whether or not :ref:`Package
5948      Test <dev-manual/common-tasks:testing packages with ptest>` (ptest)
5949      functionality is enabled when building a recipe. You should not set
5950      this variable directly. Enabling and disabling building Package Tests
5951      at build time should be done by adding "ptest" to (or removing it
5952      from) :term:`DISTRO_FEATURES`.
5953
5954   :term:`PV`
5955      The version of the recipe. The version is normally extracted from the
5956      recipe filename. For example, if the recipe is named
5957      ``expat_2.0.1.bb``, then the default value of :term:`PV` will be "2.0.1".
5958      :term:`PV` is generally not overridden within a recipe unless it is
5959      building an unstable (i.e. development) version from a source code
5960      repository (e.g. Git or Subversion).
5961
5962      :term:`PV` is the default value of the :term:`PKGV` variable.
5963
5964   :term:`PYTHON_ABI`
5965      When used by recipes that inherit the
5966      :ref:`distutils3 <ref-classes-distutils3>`,
5967      :ref:`setuptools3 <ref-classes-setuptools3>` classes, denotes the
5968      Application Binary Interface (ABI) currently in use for Python. By
5969      default, the ABI is "m". You do not have to set this variable as the
5970      OpenEmbedded build system sets it for you.
5971
5972      The OpenEmbedded build system uses the ABI to construct directory
5973      names used when installing the Python headers and libraries in
5974      sysroot (e.g. ``.../python3.3m/...``).
5975
5976      Recipes that inherit the ``distutils3`` class during cross-builds also
5977      use this variable to locate the headers and libraries of the
5978      appropriate Python that the extension is targeting.
5979
5980   :term:`PYTHON_PN`
5981      When used by recipes that inherit the
5982      `distutils3 <ref-classes-distutils3>`,
5983      :ref:`setuptools3 <ref-classes-setuptools3>` classes, specifies the
5984      major Python version being built. For Python 3.x, :term:`PYTHON_PN` would
5985      be "python3". You do not have to set this variable as the
5986      OpenEmbedded build system automatically sets it for you.
5987
5988      The variable allows recipes to use common infrastructure such as the
5989      following::
5990
5991         DEPENDS += "${PYTHON_PN}-native"
5992
5993      In the previous example,
5994      the version of the dependency is :term:`PYTHON_PN`.
5995
5996   :term:`RANLIB`
5997      The minimal command and arguments to run ``ranlib``.
5998
5999   :term:`RCONFLICTS`
6000      The list of packages that conflict with packages. Note that packages
6001      will not be installed if conflicting packages are not first removed.
6002
6003      Like all package-controlling variables, you must always use them in
6004      conjunction with a package name override. Here is an example::
6005
6006         RCONFLICTS:${PN} = "another_conflicting_package_name"
6007
6008      BitBake, which the OpenEmbedded build system uses, supports
6009      specifying versioned dependencies. Although the syntax varies
6010      depending on the packaging format, BitBake hides these differences
6011      from you. Here is the general syntax to specify versions with the
6012      :term:`RCONFLICTS` variable::
6013
6014         RCONFLICTS:${PN} = "package (operator version)"
6015
6016      For ``operator``, you can specify the following:
6017
6018      - =
6019      - <
6020      - >
6021      - <=
6022      - >=
6023
6024      For example, the following sets up a dependency on version 1.2 or
6025      greater of the package ``foo``::
6026
6027         RCONFLICTS:${PN} = "foo (>= 1.2)"
6028
6029   :term:`RDEPENDS`
6030      Lists runtime dependencies of a package. These dependencies are other
6031      packages that must be installed in order for the package to function
6032      correctly. As an example, the following assignment declares that the
6033      package ``foo`` needs the packages ``bar`` and ``baz`` to be
6034      installed::
6035
6036         RDEPENDS:foo = "bar baz"
6037
6038      The most common types of package
6039      runtime dependencies are automatically detected and added. Therefore,
6040      most recipes do not need to set :term:`RDEPENDS`. For more information,
6041      see the
6042      ":ref:`overview-manual/concepts:automatically added runtime dependencies`"
6043      section in the Yocto Project Overview and Concepts Manual.
6044
6045      The practical effect of the above :term:`RDEPENDS` assignment is that
6046      ``bar`` and ``baz`` will be declared as dependencies inside the
6047      package ``foo`` when it is written out by one of the
6048      :ref:`do_package_write_\* <ref-tasks-package_write_deb>` tasks.
6049      Exactly how this is done depends on which package format is used,
6050      which is determined by
6051      :term:`PACKAGE_CLASSES`. When the
6052      corresponding package manager installs the package, it will know to
6053      also install the packages on which it depends.
6054
6055      To ensure that the packages ``bar`` and ``baz`` get built, the
6056      previous :term:`RDEPENDS` assignment also causes a task dependency to be
6057      added. This dependency is from the recipe's
6058      :ref:`ref-tasks-build` (not to be confused with
6059      :ref:`ref-tasks-compile`) task to the
6060      ``do_package_write_*`` task of the recipes that build ``bar`` and
6061      ``baz``.
6062
6063      The names of the packages you list within :term:`RDEPENDS` must be the
6064      names of other packages - they cannot be recipe names. Although
6065      package names and recipe names usually match, the important point
6066      here is that you are providing package names within the :term:`RDEPENDS`
6067      variable. For an example of the default list of packages created from
6068      a recipe, see the :term:`PACKAGES` variable.
6069
6070      Because the :term:`RDEPENDS` variable applies to packages being built,
6071      you should always use the variable in a form with an attached package
6072      name (remember that a single recipe can build multiple packages). For
6073      example, suppose you are building a development package that depends
6074      on the ``perl`` package. In this case, you would use the following
6075      :term:`RDEPENDS` statement::
6076
6077         RDEPENDS:${PN}-dev += "perl"
6078
6079      In the example,
6080      the development package depends on the ``perl`` package. Thus, the
6081      :term:`RDEPENDS` variable has the ``${PN}-dev`` package name as part of
6082      the variable.
6083
6084      .. note::
6085
6086         ``RDEPENDS:${PN}-dev`` includes ``${``\ :term:`PN`\ ``}``
6087         by default. This default is set in the BitBake configuration file
6088         (``meta/conf/bitbake.conf``). Be careful not to accidentally remove
6089         ``${PN}`` when modifying ``RDEPENDS:${PN}-dev``. Use the "+=" operator
6090         rather than the "=" operator.
6091
6092      The package names you use with :term:`RDEPENDS` must appear as they would
6093      in the :term:`PACKAGES` variable. The :term:`PKG` variable
6094      allows a different name to be used for the final package (e.g. the
6095      :ref:`debian <ref-classes-debian>` class uses this to rename
6096      packages), but this final package name cannot be used with
6097      :term:`RDEPENDS`, which makes sense as :term:`RDEPENDS` is meant to be
6098      independent of the package format used.
6099
6100      BitBake, which the OpenEmbedded build system uses, supports
6101      specifying versioned dependencies. Although the syntax varies
6102      depending on the packaging format, BitBake hides these differences
6103      from you. Here is the general syntax to specify versions with the
6104      :term:`RDEPENDS` variable::
6105
6106         RDEPENDS:${PN} = "package (operator version)"
6107
6108      For ``operator``, you can specify the following:
6109
6110      - =
6111      - <
6112      - >
6113      - <=
6114      - >=
6115
6116      For version, provide the version number.
6117
6118      .. note::
6119
6120         You can use :term:`EXTENDPKGV` to provide a full package version
6121         specification.
6122
6123      For example, the following sets up a dependency on version 1.2 or
6124      greater of the package ``foo``::
6125
6126         RDEPENDS:${PN} = "foo (>= 1.2)"
6127
6128      For information on build-time dependencies, see the
6129      :term:`DEPENDS` variable. You can also see the
6130      ":ref:`bitbake:bitbake-user-manual/bitbake-user-manual-metadata:tasks`" and
6131      ":ref:`bitbake:bitbake-user-manual/bitbake-user-manual-execution:dependencies`" sections in the
6132      BitBake User Manual for additional information on tasks and
6133      dependencies.
6134
6135   :term:`REQUIRED_DISTRO_FEATURES`
6136      When inheriting the
6137      :ref:`features_check <ref-classes-features_check>`
6138      class, this variable identifies distribution features that must exist
6139      in the current configuration in order for the OpenEmbedded build
6140      system to build the recipe. In other words, if the
6141      :term:`REQUIRED_DISTRO_FEATURES` variable lists a feature that does not
6142      appear in :term:`DISTRO_FEATURES` within the current configuration, then
6143      the recipe will be skipped, and if the build system attempts to build
6144      the recipe then an error will be triggered.
6145
6146   :term:`REQUIRED_VERSION`
6147      If there are multiple versions of a recipe available, this variable
6148      determines which version should be given preference.
6149      :term:`REQUIRED_VERSION` works in exactly the same manner as
6150      :term:`PREFERRED_VERSION`, except that if the specified version is not
6151      available then an error message is shown and the build fails
6152      immediately.
6153
6154      If both :term:`REQUIRED_VERSION` and :term:`PREFERRED_VERSION` are set
6155      for the same recipe, the :term:`REQUIRED_VERSION` value applies.
6156
6157   :term:`RM_WORK_EXCLUDE`
6158      With ``rm_work`` enabled, this variable specifies a list of recipes
6159      whose work directories should not be removed. See the
6160      ":ref:`rm_work.bbclass <ref-classes-rm-work>`" section for more
6161      details.
6162
6163   :term:`ROOT_HOME`
6164      Defines the root home directory. By default, this directory is set as
6165      follows in the BitBake configuration file::
6166
6167         ROOT_HOME ??= "/home/root"
6168
6169      .. note::
6170
6171         This default value is likely used because some embedded solutions
6172         prefer to have a read-only root filesystem and prefer to keep
6173         writeable data in one place.
6174
6175      You can override the default by setting the variable in any layer or
6176      in the ``local.conf`` file. Because the default is set using a "weak"
6177      assignment (i.e. "??="), you can use either of the following forms to
6178      define your override::
6179
6180         ROOT_HOME = "/root"
6181         ROOT_HOME ?= "/root"
6182
6183      These
6184      override examples use ``/root``, which is probably the most commonly
6185      used override.
6186
6187   :term:`ROOTFS`
6188      Indicates a filesystem image to include as the root filesystem.
6189
6190      The :term:`ROOTFS` variable is an optional variable used with the
6191      :ref:`image-live <ref-classes-image-live>` class.
6192
6193   :term:`ROOTFS_POSTINSTALL_COMMAND`
6194      Specifies a list of functions to call after the OpenEmbedded build
6195      system has installed packages. You can specify functions separated by
6196      semicolons::
6197
6198         ROOTFS_POSTINSTALL_COMMAND += "function; ... "
6199
6200      If you need to pass the root filesystem path to a command within a
6201      function, you can use ``${IMAGE_ROOTFS}``, which points to the
6202      directory that becomes the root filesystem image. See the
6203      :term:`IMAGE_ROOTFS` variable for more
6204      information.
6205
6206   :term:`ROOTFS_POSTPROCESS_COMMAND`
6207      Specifies a list of functions to call once the OpenEmbedded build
6208      system has created the root filesystem. You can specify functions
6209      separated by semicolons::
6210
6211         ROOTFS_POSTPROCESS_COMMAND += "function; ... "
6212
6213      If you need to pass the root filesystem path to a command within a
6214      function, you can use ``${IMAGE_ROOTFS}``, which points to the
6215      directory that becomes the root filesystem image. See the
6216      :term:`IMAGE_ROOTFS` variable for more
6217      information.
6218
6219   :term:`ROOTFS_POSTUNINSTALL_COMMAND`
6220      Specifies a list of functions to call after the OpenEmbedded build
6221      system has removed unnecessary packages. When runtime package
6222      management is disabled in the image, several packages are removed
6223      including ``base-passwd``, ``shadow``, and ``update-alternatives``.
6224      You can specify functions separated by semicolons::
6225
6226         ROOTFS_POSTUNINSTALL_COMMAND += "function; ... "
6227
6228      If you need to pass the root filesystem path to a command within a
6229      function, you can use ``${IMAGE_ROOTFS}``, which points to the
6230      directory that becomes the root filesystem image. See the
6231      :term:`IMAGE_ROOTFS` variable for more
6232      information.
6233
6234   :term:`ROOTFS_PREPROCESS_COMMAND`
6235      Specifies a list of functions to call before the OpenEmbedded build
6236      system has created the root filesystem. You can specify functions
6237      separated by semicolons::
6238
6239         ROOTFS_PREPROCESS_COMMAND += "function; ... "
6240
6241      If you need to pass the root filesystem path to a command within a
6242      function, you can use ``${IMAGE_ROOTFS}``, which points to the
6243      directory that becomes the root filesystem image. See the
6244      :term:`IMAGE_ROOTFS` variable for more
6245      information.
6246
6247   :term:`RPROVIDES`
6248      A list of package name aliases that a package also provides. These
6249      aliases are useful for satisfying runtime dependencies of other
6250      packages both during the build and on the target (as specified by
6251      :term:`RDEPENDS`).
6252
6253      .. note::
6254
6255         A package's own name is implicitly already in its :term:`RPROVIDES` list.
6256
6257      As with all package-controlling variables, you must always use the
6258      variable in conjunction with a package name override. Here is an
6259      example::
6260
6261         RPROVIDES:${PN} = "widget-abi-2"
6262
6263   :term:`RRECOMMENDS`
6264      A list of packages that extends the usability of a package being
6265      built. The package being built does not depend on this list of
6266      packages in order to successfully build, but rather uses them for
6267      extended usability. To specify runtime dependencies for packages, see
6268      the :term:`RDEPENDS` variable.
6269
6270      The package manager will automatically install the :term:`RRECOMMENDS`
6271      list of packages when installing the built package. However, you can
6272      prevent listed packages from being installed by using the
6273      :term:`BAD_RECOMMENDATIONS`,
6274      :term:`NO_RECOMMENDATIONS`, and
6275      :term:`PACKAGE_EXCLUDE` variables.
6276
6277      Packages specified in :term:`RRECOMMENDS` need not actually be produced.
6278      However, there must be a recipe providing each package, either
6279      through the :term:`PACKAGES` or
6280      :term:`PACKAGES_DYNAMIC` variables or the
6281      :term:`RPROVIDES` variable, or an error will occur
6282      during the build. If such a recipe does exist and the package is not
6283      produced, the build continues without error.
6284
6285      Because the :term:`RRECOMMENDS` variable applies to packages being built,
6286      you should always attach an override to the variable to specify the
6287      particular package whose usability is being extended. For example,
6288      suppose you are building a development package that is extended to
6289      support wireless functionality. In this case, you would use the
6290      following::
6291
6292         RRECOMMENDS:${PN}-dev += "wireless_package_name"
6293
6294      In the
6295      example, the package name (``${PN}-dev``) must appear as it would in
6296      the :term:`PACKAGES` namespace before any renaming of the output package
6297      by classes such as ``debian.bbclass``.
6298
6299      BitBake, which the OpenEmbedded build system uses, supports
6300      specifying versioned recommends. Although the syntax varies depending
6301      on the packaging format, BitBake hides these differences from you.
6302      Here is the general syntax to specify versions with the
6303      :term:`RRECOMMENDS` variable::
6304
6305         RRECOMMENDS:${PN} = "package (operator version)"
6306
6307      For ``operator``, you can specify the following:
6308
6309      - =
6310      - <
6311      - >
6312      - <=
6313      - >=
6314
6315      For example, the following sets up a recommend on version 1.2 or
6316      greater of the package ``foo``::
6317
6318         RRECOMMENDS:${PN} = "foo (>= 1.2)"
6319
6320   :term:`RREPLACES`
6321      A list of packages replaced by a package. The package manager uses
6322      this variable to determine which package should be installed to
6323      replace other package(s) during an upgrade. In order to also have the
6324      other package(s) removed at the same time, you must add the name of
6325      the other package to the :term:`RCONFLICTS` variable.
6326
6327      As with all package-controlling variables, you must use this variable
6328      in conjunction with a package name override. Here is an example::
6329
6330         RREPLACES:${PN} = "other_package_being_replaced"
6331
6332      BitBake, which the OpenEmbedded build system uses, supports
6333      specifying versioned replacements. Although the syntax varies
6334      depending on the packaging format, BitBake hides these differences
6335      from you. Here is the general syntax to specify versions with the
6336      :term:`RREPLACES` variable::
6337
6338         RREPLACES:${PN} = "package (operator version)"
6339
6340      For ``operator``, you can specify the following:
6341
6342      - =
6343      - <
6344      - >
6345      - <=
6346      - >=
6347
6348      For example, the following sets up a replacement using version 1.2
6349      or greater of the package ``foo``::
6350
6351          RREPLACES:${PN} = "foo (>= 1.2)"
6352
6353   :term:`RSUGGESTS`
6354      A list of additional packages that you can suggest for installation
6355      by the package manager at the time a package is installed. Not all
6356      package managers support this functionality.
6357
6358      As with all package-controlling variables, you must always use this
6359      variable in conjunction with a package name override. Here is an
6360      example::
6361
6362         RSUGGESTS:${PN} = "useful_package another_package"
6363
6364   :term:`S`
6365      The location in the :term:`Build Directory` where
6366      unpacked recipe source code resides. By default, this directory is
6367      ``${``\ :term:`WORKDIR`\ ``}/${``\ :term:`BPN`\ ``}-${``\ :term:`PV`\ ``}``,
6368      where ``${BPN}`` is the base recipe name and ``${PV}`` is the recipe
6369      version. If the source tarball extracts the code to a directory named
6370      anything other than ``${BPN}-${PV}``, or if the source code is
6371      fetched from an SCM such as Git or Subversion, then you must set
6372      :term:`S` in the recipe so that the OpenEmbedded build system knows where
6373      to find the unpacked source.
6374
6375      As an example, assume a :term:`Source Directory`
6376      top-level folder named ``poky`` and a default Build Directory at
6377      ``poky/build``. In this case, the work directory the build system
6378      uses to keep the unpacked recipe for ``db`` is the following::
6379
6380         poky/build/tmp/work/qemux86-poky-linux/db/5.1.19-r3/db-5.1.19
6381
6382      The unpacked source code resides in the ``db-5.1.19`` folder.
6383
6384      This next example assumes a Git repository. By default, Git
6385      repositories are cloned to ``${WORKDIR}/git`` during
6386      :ref:`ref-tasks-fetch`. Since this path is different
6387      from the default value of :term:`S`, you must set it specifically so the
6388      source can be located::
6389
6390         SRC_URI = "git://path/to/repo.git"
6391         S = "${WORKDIR}/git"
6392
6393   :term:`SANITY_REQUIRED_UTILITIES`
6394      Specifies a list of command-line utilities that should be checked for
6395      during the initial sanity checking process when running BitBake. If
6396      any of the utilities are not installed on the build host, then
6397      BitBake immediately exits with an error.
6398
6399   :term:`SANITY_TESTED_DISTROS`
6400      A list of the host distribution identifiers that the build system has
6401      been tested against. Identifiers consist of the host distributor ID
6402      followed by the release, as reported by the ``lsb_release`` tool or
6403      as read from ``/etc/lsb-release``. Separate the list items with
6404      explicit newline characters (``\n``). If :term:`SANITY_TESTED_DISTROS` is
6405      not empty and the current value of
6406      :term:`NATIVELSBSTRING` does not appear in the
6407      list, then the build system reports a warning that indicates the
6408      current host distribution has not been tested as a build host.
6409
6410   :term:`SDK_ARCH`
6411      The target architecture for the SDK. Typically, you do not directly
6412      set this variable. Instead, use :term:`SDKMACHINE`.
6413
6414   :term:`SDK_CUSTOM_TEMPLATECONF`
6415      When building the extensible SDK, if :term:`SDK_CUSTOM_TEMPLATECONF` is set to
6416      "1" and a ``conf/templateconf.conf`` file exists in the build directory
6417      (:term:`TOPDIR`) then this will be copied into the SDK.
6418
6419   :term:`SDK_DEPLOY`
6420      The directory set up and used by the
6421      :ref:`populate_sdk_base <ref-classes-populate-sdk>` class to which
6422      the SDK is deployed. The ``populate_sdk_base`` class defines
6423      :term:`SDK_DEPLOY` as follows::
6424
6425         SDK_DEPLOY = "${TMPDIR}/deploy/sdk"
6426
6427   :term:`SDK_DIR`
6428      The parent directory used by the OpenEmbedded build system when
6429      creating SDK output. The
6430      :ref:`populate_sdk_base <ref-classes-populate-sdk-*>` class defines
6431      the variable as follows::
6432
6433         SDK_DIR = "${WORKDIR}/sdk"
6434
6435      .. note::
6436
6437         The :term:`SDK_DIR` directory is a temporary directory as it is part of
6438         :term:`WORKDIR`. The final output directory is :term:`SDK_DEPLOY`.
6439
6440   :term:`SDK_EXT_TYPE`
6441      Controls whether or not shared state artifacts are copied into the
6442      extensible SDK. The default value of "full" copies all of the
6443      required shared state artifacts into the extensible SDK. The value
6444      "minimal" leaves these artifacts out of the SDK.
6445
6446      .. note::
6447
6448         If you set the variable to "minimal", you need to ensure
6449         :term:`SSTATE_MIRRORS` is set in the SDK's configuration to enable the
6450         artifacts to be fetched as needed.
6451
6452   :term:`SDK_HOST_MANIFEST`
6453      The manifest file for the host part of the SDK. This file lists all
6454      the installed packages that make up the host part of the SDK. The
6455      file contains package information on a line-per-package basis as
6456      follows::
6457
6458         packagename packagearch version
6459
6460      The :ref:`populate_sdk_base <ref-classes-populate-sdk-*>` class
6461      defines the manifest file as follows::
6462
6463         SDK_HOST_MANIFEST = "${SDK_DEPLOY}/${TOOLCHAIN_OUTPUTNAME}.host.manifest"
6464
6465      The location is derived using the :term:`SDK_DEPLOY` and
6466      :term:`TOOLCHAIN_OUTPUTNAME` variables.
6467
6468   :term:`SDK_INCLUDE_PKGDATA`
6469      When set to "1", specifies to include the packagedata for all recipes
6470      in the "world" target in the extensible SDK. Including this data
6471      allows the ``devtool search`` command to find these recipes in search
6472      results, as well as allows the ``devtool add`` command to map
6473      dependencies more effectively.
6474
6475      .. note::
6476
6477         Enabling the :term:`SDK_INCLUDE_PKGDATA`
6478         variable significantly increases build time because all of world
6479         needs to be built. Enabling the variable also slightly increases
6480         the size of the extensible SDK.
6481
6482   :term:`SDK_INCLUDE_TOOLCHAIN`
6483      When set to "1", specifies to include the toolchain in the extensible
6484      SDK. Including the toolchain is useful particularly when
6485      :term:`SDK_EXT_TYPE` is set to "minimal" to keep
6486      the SDK reasonably small but you still want to provide a usable
6487      toolchain. For example, suppose you want to use the toolchain from an
6488      IDE or from other tools and you do not want to perform additional
6489      steps to install the toolchain.
6490
6491      The :term:`SDK_INCLUDE_TOOLCHAIN` variable defaults to "0" if
6492      :term:`SDK_EXT_TYPE` is set to "minimal", and defaults to "1" if
6493      :term:`SDK_EXT_TYPE` is set to "full".
6494
6495   :term:`SDK_INHERIT_BLACKLIST`
6496      A list of classes to remove from the :term:`INHERIT`
6497      value globally within the extensible SDK configuration. The
6498      :ref:`populate-sdk-ext <ref-classes-populate-sdk-*>` class sets the
6499      default value::
6500
6501         SDK_INHERIT_BLACKLIST ?= "buildhistory icecc"
6502
6503      Some classes are not generally applicable within the extensible SDK
6504      context. You can use this variable to disable those classes.
6505
6506      For additional information on how to customize the extensible SDK's
6507      configuration, see the
6508      ":ref:`sdk-manual/appendix-customizing:configuring the extensible sdk`"
6509      section in the Yocto Project Application Development and the
6510      Extensible Software Development Kit (eSDK) manual.
6511
6512   :term:`SDK_LOCAL_CONF_BLACKLIST`
6513      A list of variables not allowed through from the OpenEmbedded build
6514      system configuration into the extensible SDK configuration. Usually,
6515      these are variables that are specific to the machine on which the
6516      build system is running and thus would be potentially problematic
6517      within the extensible SDK.
6518
6519      By default, :term:`SDK_LOCAL_CONF_BLACKLIST` is set in the
6520      :ref:`populate-sdk-ext <ref-classes-populate-sdk-*>` class and
6521      excludes the following variables:
6522
6523      - :term:`CONF_VERSION`
6524      - :term:`BB_NUMBER_THREADS`
6525      - :term:`BB_NUMBER_PARSE_THREADS`
6526      - :term:`PARALLEL_MAKE`
6527      - :term:`PRSERV_HOST`
6528      - :term:`SSTATE_MIRRORS` :term:`DL_DIR`
6529      - :term:`SSTATE_DIR` :term:`TMPDIR`
6530      - :term:`BB_SERVER_TIMEOUT`
6531
6532      For additional information on how to customize the extensible SDK's
6533      configuration, see the
6534      ":ref:`sdk-manual/appendix-customizing:configuring the extensible sdk`"
6535      section in the Yocto Project Application Development and the
6536      Extensible Software Development Kit (eSDK) manual.
6537
6538   :term:`SDK_LOCAL_CONF_WHITELIST`
6539      A list of variables allowed through from the OpenEmbedded build
6540      system configuration into the extensible SDK configuration. By
6541      default, the list of variables is empty and is set in the
6542      :ref:`populate-sdk-ext <ref-classes-populate-sdk-*>` class.
6543
6544      This list overrides the variables specified using the
6545      :term:`SDK_LOCAL_CONF_BLACKLIST`
6546      variable as well as any variables identified by automatic
6547      blacklisting due to the "/" character being found at the start of the
6548      value, which is usually indicative of being a path and thus might not
6549      be valid on the system where the SDK is installed.
6550
6551      For additional information on how to customize the extensible SDK's
6552      configuration, see the
6553      ":ref:`sdk-manual/appendix-customizing:configuring the extensible sdk`"
6554      section in the Yocto Project Application Development and the
6555      Extensible Software Development Kit (eSDK) manual.
6556
6557   :term:`SDK_NAME`
6558      The base name for SDK output files. The name is derived from the
6559      :term:`DISTRO`, :term:`TCLIBC`,
6560      :term:`SDK_ARCH`,
6561      :term:`IMAGE_BASENAME`, and
6562      :term:`TUNE_PKGARCH` variables::
6563
6564         SDK_NAME = "${DISTRO}-${TCLIBC}-${SDK_ARCH}-${IMAGE_BASENAME}-${TUNE_PKGARCH}"
6565
6566   :term:`SDK_OS`
6567      Specifies the operating system for which the SDK will be built. The
6568      default value is the value of :term:`BUILD_OS`.
6569
6570   :term:`SDK_OUTPUT`
6571      The location used by the OpenEmbedded build system when creating SDK
6572      output. The :ref:`populate_sdk_base <ref-classes-populate-sdk-*>`
6573      class defines the variable as follows::
6574
6575         SDK_DIR = "${WORKDIR}/sdk"
6576         SDK_OUTPUT = "${SDK_DIR}/image"
6577         SDK_DEPLOY = "${DEPLOY_DIR}/sdk"
6578
6579      .. note::
6580
6581         The :term:`SDK_OUTPUT` directory is a temporary directory as it is part of
6582         :term:`WORKDIR` by way of :term:`SDK_DIR`. The final output directory is
6583         :term:`SDK_DEPLOY`.
6584
6585   :term:`SDK_PACKAGE_ARCHS`
6586      Specifies a list of architectures compatible with the SDK machine.
6587      This variable is set automatically and should not normally be
6588      hand-edited. Entries are separated using spaces and listed in order
6589      of priority. The default value for :term:`SDK_PACKAGE_ARCHS` is "all any
6590      noarch ${SDK_ARCH}-${SDKPKGSUFFIX}".
6591
6592   :term:`SDK_POSTPROCESS_COMMAND`
6593      Specifies a list of functions to call once the OpenEmbedded build
6594      system creates the SDK. You can specify functions separated by
6595      semicolons: SDK_POSTPROCESS_COMMAND += "function; ... "
6596
6597      If you need to pass an SDK path to a command within a function, you
6598      can use ``${SDK_DIR}``, which points to the parent directory used by
6599      the OpenEmbedded build system when creating SDK output. See the
6600      :term:`SDK_DIR` variable for more information.
6601
6602   :term:`SDK_PREFIX`
6603      The toolchain binary prefix used for ``nativesdk`` recipes. The
6604      OpenEmbedded build system uses the :term:`SDK_PREFIX` value to set the
6605      :term:`TARGET_PREFIX` when building
6606      ``nativesdk`` recipes. The default value is "${SDK_SYS}-".
6607
6608   :term:`SDK_RECRDEP_TASKS`
6609      A list of shared state tasks added to the extensible SDK. By default,
6610      the following tasks are added:
6611
6612      - do_populate_lic
6613      - do_package_qa
6614      - do_populate_sysroot
6615      - do_deploy
6616
6617      Despite the default value of "" for the
6618      :term:`SDK_RECRDEP_TASKS` variable, the above four tasks are always added
6619      to the SDK. To specify tasks beyond these four, you need to use the
6620      :term:`SDK_RECRDEP_TASKS` variable (e.g. you are defining additional
6621      tasks that are needed in order to build
6622      :term:`SDK_TARGETS`).
6623
6624   :term:`SDK_SYS`
6625      Specifies the system, including the architecture and the operating
6626      system, for which the SDK will be built.
6627
6628      The OpenEmbedded build system automatically sets this variable based
6629      on :term:`SDK_ARCH`,
6630      :term:`SDK_VENDOR`, and
6631      :term:`SDK_OS`. You do not need to set the :term:`SDK_SYS`
6632      variable yourself.
6633
6634   :term:`SDK_TARGET_MANIFEST`
6635      The manifest file for the target part of the SDK. This file lists all
6636      the installed packages that make up the target part of the SDK. The
6637      file contains package information on a line-per-package basis as
6638      follows::
6639
6640         packagename packagearch version
6641
6642      The :ref:`populate_sdk_base <ref-classes-populate-sdk-*>` class
6643      defines the manifest file as follows::
6644
6645         SDK_TARGET_MANIFEST = "${SDK_DEPLOY}/${TOOLCHAIN_OUTPUTNAME}.target.manifest"
6646
6647      The location is derived using the :term:`SDK_DEPLOY` and
6648      :term:`TOOLCHAIN_OUTPUTNAME` variables.
6649
6650   :term:`SDK_TARGETS`
6651      A list of targets to install from shared state as part of the
6652      standard or extensible SDK installation. The default value is "${PN}"
6653      (i.e. the image from which the SDK is built).
6654
6655      The :term:`SDK_TARGETS` variable is an internal variable and typically
6656      would not be changed.
6657
6658   :term:`SDK_TITLE`
6659      The title to be printed when running the SDK installer. By default,
6660      this title is based on the :term:`DISTRO_NAME` or
6661      :term:`DISTRO` variable and is set in the
6662      :ref:`populate_sdk_base <ref-classes-populate-sdk-*>` class as
6663      follows::
6664
6665         SDK_TITLE ??= "${@d.getVar('DISTRO_NAME') or d.getVar('DISTRO')} SDK"
6666
6667      For the default distribution "poky",
6668      :term:`SDK_TITLE` is set to "Poky (Yocto Project Reference Distro)".
6669
6670      For information on how to change this default title, see the
6671      ":ref:`sdk-manual/appendix-customizing:changing the extensible sdk installer title`"
6672      section in the Yocto Project Application Development and the
6673      Extensible Software Development Kit (eSDK) manual.
6674
6675   :term:`SDK_UPDATE_URL`
6676      An optional URL for an update server for the extensible SDK. If set,
6677      the value is used as the default update server when running
6678      ``devtool sdk-update`` within the extensible SDK.
6679
6680   :term:`SDK_VENDOR`
6681      Specifies the name of the SDK vendor.
6682
6683   :term:`SDK_VERSION`
6684      Specifies the version of the SDK. The Poky distribution configuration file
6685      (``/meta-poky/conf/distro/poky.conf``) sets the default
6686      :term:`SDK_VERSION` as follows::
6687
6688         SDK_VERSION = "${@d.getVar('DISTRO_VERSION').replace('snapshot-${METADATA_REVISION}', 'snapshot')}"
6689
6690      For additional information, see the
6691      :term:`DISTRO_VERSION` and
6692      :term:`METADATA_REVISION` variables.
6693
6694   :term:`SDKEXTPATH`
6695      The default installation directory for the Extensible SDK. By
6696      default, this directory is based on the :term:`DISTRO`
6697      variable and is set in the
6698      :ref:`populate_sdk_base <ref-classes-populate-sdk-*>` class as
6699      follows::
6700
6701         SDKEXTPATH ??= "~/${@d.getVar('DISTRO')}_sdk"
6702
6703      For the
6704      default distribution "poky", the :term:`SDKEXTPATH` is set to "poky_sdk".
6705
6706      For information on how to change this default directory, see the
6707      ":ref:`sdk-manual/appendix-customizing:changing the default sdk installation directory`"
6708      section in the Yocto Project Application Development and the
6709      Extensible Software Development Kit (eSDK) manual.
6710
6711   :term:`SDKIMAGE_FEATURES`
6712      Equivalent to :term:`IMAGE_FEATURES`. However, this variable applies to
6713      the SDK generated from an image using the following command::
6714
6715         $ bitbake -c populate_sdk imagename
6716
6717   :term:`SDKMACHINE`
6718      The machine for which the SDK is built. In other words, the SDK is
6719      built such that it runs on the target you specify with the
6720      :term:`SDKMACHINE` value. The value points to a corresponding ``.conf``
6721      file under ``conf/machine-sdk/``.
6722
6723      You can use "i686" and "x86_64" as possible values for this variable.
6724      The variable defaults to "i686" and is set in the local.conf file in
6725      the Build Directory.
6726      ::
6727
6728         SDKMACHINE ?= "i686"
6729
6730      .. note::
6731
6732         You cannot set the :term:`SDKMACHINE`
6733         variable in your distribution configuration file. If you do, the
6734         configuration will not take affect.
6735
6736   :term:`SDKPATH`
6737      Defines the path offered to the user for installation of the SDK that
6738      is generated by the OpenEmbedded build system. The path appears as
6739      the default location for installing the SDK when you run the SDK's
6740      installation script. You can override the offered path when you run
6741      the script.
6742
6743   :term:`SDKTARGETSYSROOT`
6744      The full path to the sysroot used for cross-compilation within an SDK
6745      as it will be when installed into the default
6746      :term:`SDKPATH`.
6747
6748   :term:`SECTION`
6749      The section in which packages should be categorized. Package
6750      management utilities can make use of this variable.
6751
6752   :term:`SELECTED_OPTIMIZATION`
6753      Specifies the optimization flags passed to the C compiler when
6754      building for the target. The flags are passed through the default
6755      value of the :term:`TARGET_CFLAGS` variable.
6756
6757      The :term:`SELECTED_OPTIMIZATION` variable takes the value of
6758      :term:`FULL_OPTIMIZATION` unless :term:`DEBUG_BUILD` = "1", in which
6759      case the value of :term:`DEBUG_OPTIMIZATION` is used.
6760
6761   :term:`SERIAL_CONSOLE`
6762      Defines a serial console (TTY) to enable using
6763      `getty <https://en.wikipedia.org/wiki/Getty_(Unix)>`__. Provide a
6764      value that specifies the baud rate followed by the TTY device name
6765      separated by a space. You cannot specify more than one TTY device::
6766
6767         SERIAL_CONSOLE = "115200 ttyS0"
6768
6769      .. note::
6770
6771         The :term:`SERIAL_CONSOLE` variable is deprecated. Please use the
6772         :term:`SERIAL_CONSOLES` variable.
6773
6774   :term:`SERIAL_CONSOLES`
6775      Defines a serial console (TTY) to enable using
6776      `getty <https://en.wikipedia.org/wiki/Getty_(Unix)>`__. Provide a
6777      value that specifies the baud rate followed by the TTY device name
6778      separated by a semicolon. Use spaces to separate multiple devices::
6779
6780         SERIAL_CONSOLES = "115200;ttyS0 115200;ttyS1"
6781
6782   :term:`SERIAL_CONSOLES_CHECK`
6783      Specifies serial consoles, which must be listed in
6784      :term:`SERIAL_CONSOLES`, to check against
6785      ``/proc/console`` before enabling them using getty. This variable
6786      allows aliasing in the format: <device>:<alias>. If a device was
6787      listed as "sclp_line0" in ``/dev/`` and "ttyS0" was listed in
6788      ``/proc/console``, you would do the following::
6789
6790         SERIAL_CONSOLES_CHECK = "slcp_line0:ttyS0"
6791
6792      This variable is currently only supported with SysVinit (i.e. not
6793      with systemd). Note that :term:`SERIAL_CONSOLES_CHECK` also requires
6794      ``/etc/inittab`` to be writable when used with SysVinit. This makes it
6795      incompatible with customizations such as the following::
6796
6797         EXTRA_IMAGE_FEATURES += "read-only-rootfs"
6798
6799   :term:`SIGGEN_EXCLUDE_SAFE_RECIPE_DEPS`
6800      A list of recipe dependencies that should not be used to determine
6801      signatures of tasks from one recipe when they depend on tasks from
6802      another recipe. For example::
6803
6804         SIGGEN_EXCLUDE_SAFE_RECIPE_DEPS += "intone->mplayer2"
6805
6806      In the previous example, ``intone`` depends on ``mplayer2``.
6807
6808      You can use the special token ``"*"`` on the left-hand side of the
6809      dependency to match all recipes except the one on the right-hand
6810      side. Here is an example::
6811
6812         SIGGEN_EXCLUDE_SAFE_RECIPE_DEPS += "*->quilt-native"
6813
6814      In the previous example, all recipes except ``quilt-native`` ignore
6815      task signatures from the ``quilt-native`` recipe when determining
6816      their task signatures.
6817
6818      Use of this variable is one mechanism to remove dependencies that
6819      affect task signatures and thus force rebuilds when a recipe changes.
6820
6821      .. note::
6822
6823         If you add an inappropriate dependency for a recipe relationship,
6824         the software might break during runtime if the interface of the
6825         second recipe was changed after the first recipe had been built.
6826
6827   :term:`SIGGEN_EXCLUDERECIPES_ABISAFE`
6828      A list of recipes that are completely stable and will never change.
6829      The ABI for the recipes in the list are presented by output from the
6830      tasks run to build the recipe. Use of this variable is one way to
6831      remove dependencies from one recipe on another that affect task
6832      signatures and thus force rebuilds when the recipe changes.
6833
6834      .. note::
6835
6836         If you add an inappropriate variable to this list, the software
6837         might break at runtime if the interface of the recipe was changed
6838         after the other had been built.
6839
6840   :term:`SITEINFO_BITS`
6841      Specifies the number of bits for the target system CPU. The value
6842      should be either "32" or "64".
6843
6844   :term:`SITEINFO_ENDIANNESS`
6845      Specifies the endian byte order of the target system. The value
6846      should be either "le" for little-endian or "be" for big-endian.
6847
6848   :term:`SKIP_FILEDEPS`
6849      Enables removal of all files from the "Provides" section of an RPM
6850      package. Removal of these files is required for packages containing
6851      prebuilt binaries and libraries such as ``libstdc++`` and ``glibc``.
6852
6853      To enable file removal, set the variable to "1" in your
6854      ``conf/local.conf`` configuration file in your:
6855      :term:`Build Directory`.
6856      ::
6857
6858         SKIP_FILEDEPS = "1"
6859
6860   :term:`SOC_FAMILY`
6861      Groups together machines based upon the same family of SOC (System On
6862      Chip). You typically set this variable in a common ``.inc`` file that
6863      you include in the configuration files of all the machines.
6864
6865      .. note::
6866
6867         You must include ``conf/machine/include/soc-family.inc`` for this
6868         variable to appear in :term:`MACHINEOVERRIDES`.
6869
6870   :term:`SOLIBS`
6871      Defines the suffix for shared libraries used on the target platform.
6872      By default, this suffix is ".so.*" for all Linux-based systems and is
6873      defined in the ``meta/conf/bitbake.conf`` configuration file.
6874
6875      You will see this variable referenced in the default values of
6876      ``FILES:${PN}``.
6877
6878   :term:`SOLIBSDEV`
6879      Defines the suffix for the development symbolic link (symlink) for
6880      shared libraries on the target platform. By default, this suffix is
6881      ".so" for Linux-based systems and is defined in the
6882      ``meta/conf/bitbake.conf`` configuration file.
6883
6884      You will see this variable referenced in the default values of
6885      ``FILES:${PN}-dev``.
6886
6887   :term:`SOURCE_MIRROR_FETCH`
6888      When you are fetching files to create a mirror of sources (i.e.
6889      creating a source mirror), setting :term:`SOURCE_MIRROR_FETCH` to "1" in
6890      your ``local.conf`` configuration file ensures the source for all
6891      recipes are fetched regardless of whether or not a recipe is
6892      compatible with the configuration. A recipe is considered
6893      incompatible with the currently configured machine when either or
6894      both the :term:`COMPATIBLE_MACHINE`
6895      variable and :term:`COMPATIBLE_HOST` variables
6896      specify compatibility with a machine other than that of the current
6897      machine or host.
6898
6899      .. note::
6900
6901         Do not set the :term:`SOURCE_MIRROR_FETCH`
6902         variable unless you are creating a source mirror. In other words,
6903         do not set the variable during a normal build.
6904
6905   :term:`SOURCE_MIRROR_URL`
6906      Defines your own :term:`PREMIRRORS` from which to
6907      first fetch source before attempting to fetch from the upstream
6908      specified in :term:`SRC_URI`.
6909
6910      To use this variable, you must globally inherit the
6911      :ref:`own-mirrors <ref-classes-own-mirrors>` class and then provide
6912      the URL to your mirrors. Here is the general syntax::
6913
6914         INHERIT += "own-mirrors"
6915         SOURCE_MIRROR_URL = "http://example.com/my_source_mirror"
6916
6917      .. note::
6918
6919         You can specify only a single URL in :term:`SOURCE_MIRROR_URL`.
6920
6921   :term:`SPDXLICENSEMAP`
6922      Maps commonly used license names to their SPDX counterparts found in
6923      ``meta/files/common-licenses/``. For the default :term:`SPDXLICENSEMAP`
6924      mappings, see the ``meta/conf/licenses.conf`` file.
6925
6926      For additional information, see the :term:`LICENSE`
6927      variable.
6928
6929   :term:`SPECIAL_PKGSUFFIX`
6930      A list of prefixes for :term:`PN` used by the OpenEmbedded
6931      build system to create variants of recipes or packages. The list
6932      specifies the prefixes to strip off during certain circumstances such
6933      as the generation of the :term:`BPN` variable.
6934
6935   :term:`SPL_BINARY`
6936      The file type for the Secondary Program Loader (SPL). Some devices
6937      use an SPL from which to boot (e.g. the BeagleBone development
6938      board). For such cases, you can declare the file type of the SPL
6939      binary in the ``u-boot.inc`` include file, which is used in the
6940      U-Boot recipe.
6941
6942      The SPL file type is set to "null" by default in the ``u-boot.inc``
6943      file as follows::
6944
6945         # Some versions of u-boot build an SPL (Second Program Loader) image that
6946         # should be packaged along with the u-boot binary as well as placed in the
6947         # deploy directory. For those versions they can set the following variables
6948         # to allow packaging the SPL.
6949         SPL_BINARY ?= ""
6950         SPL_BINARYNAME ?= "${@os.path.basename(d.getVar("SPL_BINARY"))}"
6951         SPL_IMAGE ?= "${SPL_BINARYNAME}-${MACHINE}-${PV}-${PR}"
6952         SPL_SYMLINK ?= "${SPL_BINARYNAME}-${MACHINE}"
6953
6954      The :term:`SPL_BINARY` variable helps form
6955      various ``SPL_*`` variables used by the OpenEmbedded build system.
6956
6957      See the BeagleBone machine configuration example in the
6958      ":ref:`dev-manual/common-tasks:adding a layer using the \`\`bitbake-layers\`\` script`"
6959      section in the Yocto Project Board Support Package Developer's Guide
6960      for additional information.
6961
6962   :term:`SRC_URI`
6963      The list of source files - local or remote. This variable tells the
6964      OpenEmbedded build system which bits to pull in for the build and how
6965      to pull them in. For example, if the recipe or append file only needs
6966      to fetch a tarball from the Internet, the recipe or append file uses
6967      a single :term:`SRC_URI` entry. On the other hand, if the recipe or
6968      append file needs to fetch a tarball, apply two patches, and include
6969      a custom file, the recipe or append file would include four instances
6970      of the variable.
6971
6972      The following list explains the available URI protocols. URI
6973      protocols are highly dependent on particular BitBake Fetcher
6974      submodules. Depending on the fetcher BitBake uses, various URL
6975      parameters are employed. For specifics on the supported Fetchers, see
6976      the ":ref:`bitbake:bitbake-user-manual/bitbake-user-manual-fetching:fetchers`" section in the
6977      BitBake User Manual.
6978
6979      -  ``file://`` - Fetches files, which are usually files shipped
6980         with the :term:`Metadata`, from the local machine (e.g.
6981         :ref:`patch <overview-manual/concepts:patching>` files).
6982         The path is relative to the :term:`FILESPATH`
6983         variable. Thus, the build system searches, in order, from the
6984         following directories, which are assumed to be a subdirectories of
6985         the directory in which the recipe file (``.bb``) or append file
6986         (``.bbappend``) resides:
6987
6988         -  ``${BPN}`` - The base recipe name without any special suffix
6989            or version numbers.
6990
6991         -  ``${BP}`` - ``${BPN}-${PV}``. The base recipe name and
6992            version but without any special package name suffix.
6993
6994         -  *files -* Files within a directory, which is named ``files``
6995            and is also alongside the recipe or append file.
6996
6997         .. note::
6998
6999            If you want the build system to pick up files specified through
7000            a
7001            SRC_URI
7002            statement from your append file, you need to be sure to extend
7003            the
7004            FILESPATH
7005            variable by also using the
7006            FILESEXTRAPATHS
7007            variable from within your append file.
7008
7009      -  ``bzr://`` - Fetches files from a Bazaar revision control
7010         repository.
7011
7012      -  ``git://`` - Fetches files from a Git revision control
7013         repository.
7014
7015      -  ``osc://`` - Fetches files from an OSC (openSUSE Build service)
7016         revision control repository.
7017
7018      -  ``repo://`` - Fetches files from a repo (Git) repository.
7019
7020      -  ``ccrc://`` - Fetches files from a ClearCase repository.
7021
7022      -  ``http://`` - Fetches files from the Internet using ``http``.
7023
7024      -  ``https://`` - Fetches files from the Internet using ``https``.
7025
7026      -  ``ftp://`` - Fetches files from the Internet using ``ftp``.
7027
7028      -  ``cvs://`` - Fetches files from a CVS revision control
7029         repository.
7030
7031      -  ``hg://`` - Fetches files from a Mercurial (``hg``) revision
7032         control repository.
7033
7034      -  ``p4://`` - Fetches files from a Perforce (``p4``) revision
7035         control repository.
7036
7037      -  ``ssh://`` - Fetches files from a secure shell.
7038
7039      -  ``svn://`` - Fetches files from a Subversion (``svn``) revision
7040         control repository.
7041
7042      -  ``npm://`` - Fetches JavaScript modules from a registry.
7043
7044      -  ``az://`` - Fetches files from an Azure Storage account.
7045
7046      There are standard and recipe-specific options for :term:`SRC_URI`. Here are
7047      standard ones:
7048
7049      -  ``apply`` - Whether to apply the patch or not. The default
7050         action is to apply the patch.
7051
7052      -  ``striplevel`` - Which striplevel to use when applying the
7053         patch. The default level is 1.
7054
7055      -  ``patchdir`` - Specifies the directory in which the patch should
7056         be applied. The default is ``${``\ :term:`S`\ ``}``.
7057
7058      Here are options specific to recipes building code from a revision
7059      control system:
7060
7061      -  ``mindate`` - Apply the patch only if
7062         :term:`SRCDATE` is equal to or greater than
7063         ``mindate``.
7064
7065      -  ``maxdate`` - Apply the patch only if :term:`SRCDATE` is not later
7066         than ``maxdate``.
7067
7068      -  ``minrev`` - Apply the patch only if :term:`SRCREV` is equal to or
7069         greater than ``minrev``.
7070
7071      -  ``maxrev`` - Apply the patch only if :term:`SRCREV` is not later
7072         than ``maxrev``.
7073
7074      -  ``rev`` - Apply the patch only if :term:`SRCREV` is equal to
7075         ``rev``.
7076
7077      -  ``notrev`` - Apply the patch only if :term:`SRCREV` is not equal to
7078         ``rev``.
7079
7080      Here are some additional options worth mentioning:
7081
7082      -  ``unpack`` - Controls whether or not to unpack the file if it is
7083         an archive. The default action is to unpack the file.
7084
7085      -  ``destsuffix`` - Places the file (or extracts its contents) into
7086         the specified subdirectory of :term:`WORKDIR` when
7087         the Git fetcher is used.
7088
7089      -  ``subdir`` - Places the file (or extracts its contents) into the
7090         specified subdirectory of :term:`WORKDIR` when the local (``file://``)
7091         fetcher is used.
7092
7093      -  ``localdir`` - Places the file (or extracts its contents) into
7094         the specified subdirectory of :term:`WORKDIR` when the CVS fetcher is
7095         used.
7096
7097      -  ``subpath`` - Limits the checkout to a specific subpath of the
7098         tree when using the Git fetcher is used.
7099
7100      -  ``name`` - Specifies a name to be used for association with
7101         :term:`SRC_URI` checksums or :term:`SRCREV` when you have more than one
7102         file or git repository specified in :term:`SRC_URI`. For example::
7103
7104            SRC_URI = "git://example.com/foo.git;name=first \
7105                       git://example.com/bar.git;name=second \
7106                       http://example.com/file.tar.gz;name=third"
7107
7108            SRCREV_first = "f1d2d2f924e986ac86fdf7b36c94bcdf32beec15"
7109            SRCREV_second = "e242ed3bffccdf271b7fbaf34ed72d089537b42f"
7110            SRC_URI[third.sha256sum] = "13550350a8681c84c861aac2e5b440161c2b33a3e4f302ac680ca5b686de48de"
7111
7112
7113      -  ``downloadfilename`` - Specifies the filename used when storing
7114         the downloaded file.
7115
7116   :term:`SRC_URI_OVERRIDES_PACKAGE_ARCH`
7117      By default, the OpenEmbedded build system automatically detects
7118      whether :term:`SRC_URI` contains files that are machine-specific. If so,
7119      the build system automatically changes :term:`PACKAGE_ARCH`. Setting this
7120      variable to "0" disables this behavior.
7121
7122   :term:`SRCDATE`
7123      The date of the source code used to build the package. This variable
7124      applies only if the source was fetched from a Source Code Manager
7125      (SCM).
7126
7127   :term:`SRCPV`
7128      Returns the version string of the current package. This string is
7129      used to help define the value of :term:`PV`.
7130
7131      The :term:`SRCPV` variable is defined in the ``meta/conf/bitbake.conf``
7132      configuration file in the :term:`Source Directory` as
7133      follows::
7134
7135         SRCPV = "${@bb.fetch2.get_srcrev(d)}"
7136
7137      Recipes that need to define :term:`PV` do so with the help of the
7138      :term:`SRCPV`. For example, the ``ofono`` recipe (``ofono_git.bb``)
7139      located in ``meta/recipes-connectivity`` in the Source Directory
7140      defines :term:`PV` as follows::
7141
7142         PV = "0.12-git${SRCPV}"
7143
7144   :term:`SRCREV`
7145      The revision of the source code used to build the package. This
7146      variable applies to Subversion, Git, Mercurial, and Bazaar only. Note
7147      that if you want to build a fixed revision and you want to avoid
7148      performing a query on the remote repository every time BitBake parses
7149      your recipe, you should specify a :term:`SRCREV` that is a full revision
7150      identifier and not just a tag.
7151
7152      .. note::
7153
7154         For information on limitations when inheriting the latest revision
7155         of software using :term:`SRCREV`, see the :term:`AUTOREV` variable
7156         description and the
7157         ":ref:`dev-manual/common-tasks:automatically incrementing a package version number`"
7158         section, which is in the Yocto Project Development Tasks Manual.
7159
7160   :term:`SRCTREECOVEREDTASKS`
7161      A list of tasks that are typically not relevant (and therefore skipped)
7162      when building using the :ref:`externalsrc <ref-classes-externalsrc>`
7163      class. The default value as set in that class file is the set of tasks
7164      that are rarely needed when using external source::
7165
7166         SRCTREECOVEREDTASKS ?= "do_patch do_unpack do_fetch"
7167
7168      The notable exception is when processing external kernel source as
7169      defined in the :ref:`kernel-yocto <ref-classes-kernel-yocto>`
7170      class file (formatted for aesthetics)::
7171
7172         SRCTREECOVEREDTASKS += "\
7173           do_validate_branches \
7174           do_kernel_configcheck \
7175           do_kernel_checkout \
7176           do_fetch \
7177           do_unpack \
7178           do_patch \
7179         "
7180
7181      See the associated :term:`EXTERNALSRC` and :term:`EXTERNALSRC_BUILD`
7182      variables for more information.
7183
7184   :term:`SSTATE_DIR`
7185      The directory for the shared state cache.
7186
7187   :term:`SSTATE_MIRROR_ALLOW_NETWORK`
7188      If set to "1", allows fetches from mirrors that are specified in
7189      :term:`SSTATE_MIRRORS` to work even when
7190      fetching from the network is disabled by setting :term:`BB_NO_NETWORK` to
7191      "1". Using the :term:`SSTATE_MIRROR_ALLOW_NETWORK` variable is useful if
7192      you have set :term:`SSTATE_MIRRORS` to point to an internal server for
7193      your shared state cache, but you want to disable any other fetching
7194      from the network.
7195
7196   :term:`SSTATE_MIRRORS`
7197      Configures the OpenEmbedded build system to search other mirror
7198      locations for prebuilt cache data objects before building out the
7199      data. This variable works like fetcher :term:`MIRRORS`
7200      and :term:`PREMIRRORS` and points to the cache
7201      locations to check for the shared state (sstate) objects.
7202
7203      You can specify a filesystem directory or a remote URL such as HTTP
7204      or FTP. The locations you specify need to contain the shared state
7205      cache (sstate-cache) results from previous builds. The sstate-cache
7206      you point to can also be from builds on other machines.
7207
7208      When pointing to sstate build artifacts on another machine that uses
7209      a different GCC version for native builds, you must configure
7210      :term:`SSTATE_MIRRORS` with a regular expression that maps local search
7211      paths to server paths. The paths need to take into account
7212      :term:`NATIVELSBSTRING` set by the
7213      :ref:`uninative <ref-classes-uninative>` class. For example, the
7214      following maps the local search path ``universal-4.9`` to the
7215      server-provided path server_url_sstate_path::
7216
7217         SSTATE_MIRRORS ?= "file://universal-4.9/(.*) http://server_url_sstate_path/universal-4.8/\1 \n"
7218
7219      If a mirror uses the same structure as
7220      :term:`SSTATE_DIR`, you need to add "PATH" at the
7221      end as shown in the examples below. The build system substitutes the
7222      correct path within the directory structure.
7223      ::
7224
7225         SSTATE_MIRRORS ?= "\
7226             file://.* http://someserver.tld/share/sstate/PATH;downloadfilename=PATH \n \
7227             file://.* file:///some-local-dir/sstate/PATH"
7228
7229   :term:`SSTATE_SCAN_FILES`
7230      Controls the list of files the OpenEmbedded build system scans for
7231      hardcoded installation paths. The variable uses a space-separated
7232      list of filenames (not paths) with standard wildcard characters
7233      allowed.
7234
7235      During a build, the OpenEmbedded build system creates a shared state
7236      (sstate) object during the first stage of preparing the sysroots.
7237      That object is scanned for hardcoded paths for original installation
7238      locations. The list of files that are scanned for paths is controlled
7239      by the :term:`SSTATE_SCAN_FILES` variable. Typically, recipes add files
7240      they want to be scanned to the value of :term:`SSTATE_SCAN_FILES` rather
7241      than the variable being comprehensively set. The
7242      :ref:`sstate <ref-classes-sstate>` class specifies the default list
7243      of files.
7244
7245      For details on the process, see the
7246      :ref:`staging <ref-classes-staging>` class.
7247
7248   :term:`STAGING_BASE_LIBDIR_NATIVE`
7249      Specifies the path to the ``/lib`` subdirectory of the sysroot
7250      directory for the build host.
7251
7252   :term:`STAGING_BASELIBDIR`
7253      Specifies the path to the ``/lib`` subdirectory of the sysroot
7254      directory for the target for which the current recipe is being built
7255      (:term:`STAGING_DIR_HOST`).
7256
7257   :term:`STAGING_BINDIR`
7258      Specifies the path to the ``/usr/bin`` subdirectory of the sysroot
7259      directory for the target for which the current recipe is being built
7260      (:term:`STAGING_DIR_HOST`).
7261
7262   :term:`STAGING_BINDIR_CROSS`
7263      Specifies the path to the directory containing binary configuration
7264      scripts. These scripts provide configuration information for other
7265      software that wants to make use of libraries or include files
7266      provided by the software associated with the script.
7267
7268      .. note::
7269
7270         This style of build configuration has been largely replaced by
7271         ``pkg-config``. Consequently, if ``pkg-config`` is supported by the
7272         library to which you are linking, it is recommended you use
7273         ``pkg-config`` instead of a provided configuration script.
7274
7275   :term:`STAGING_BINDIR_NATIVE`
7276      Specifies the path to the ``/usr/bin`` subdirectory of the sysroot
7277      directory for the build host.
7278
7279   :term:`STAGING_DATADIR`
7280      Specifies the path to the ``/usr/share`` subdirectory of the sysroot
7281      directory for the target for which the current recipe is being built
7282      (:term:`STAGING_DIR_HOST`).
7283
7284   :term:`STAGING_DATADIR_NATIVE`
7285      Specifies the path to the ``/usr/share`` subdirectory of the sysroot
7286      directory for the build host.
7287
7288   :term:`STAGING_DIR`
7289      Helps construct the ``recipe-sysroots`` directory, which is used
7290      during packaging.
7291
7292      For information on how staging for recipe-specific sysroots occurs,
7293      see the :ref:`ref-tasks-populate_sysroot`
7294      task, the ":ref:`sdk-manual/extensible:sharing files between recipes`"
7295      section in the Yocto Project Development Tasks Manual, the
7296      ":ref:`overview-manual/concepts:configuration, compilation, and staging`"
7297      section in the Yocto Project Overview and Concepts Manual, and the
7298      :term:`SYSROOT_DIRS` variable.
7299
7300      .. note::
7301
7302         Recipes should never write files directly under the :term:`STAGING_DIR`
7303         directory because the OpenEmbedded build system manages the
7304         directory automatically. Instead, files should be installed to
7305         ``${``\ :term:`D`\ ``}`` within your recipe's :ref:`ref-tasks-install`
7306         task and then the OpenEmbedded build system will stage a subset of
7307         those files into the sysroot.
7308
7309   :term:`STAGING_DIR_HOST`
7310      Specifies the path to the sysroot directory for the system on which
7311      the component is built to run (the system that hosts the component).
7312      For most recipes, this sysroot is the one in which that recipe's
7313      :ref:`ref-tasks-populate_sysroot` task copies
7314      files. Exceptions include ``-native`` recipes, where the
7315      ``do_populate_sysroot`` task instead uses
7316      :term:`STAGING_DIR_NATIVE`. Depending on
7317      the type of recipe and the build target, :term:`STAGING_DIR_HOST` can
7318      have the following values:
7319
7320      -  For recipes building for the target machine, the value is
7321         "${:term:`STAGING_DIR`}/${:term:`MACHINE`}".
7322
7323      -  For native recipes building for the build host, the value is empty
7324         given the assumption that when building for the build host, the
7325         build host's own directories should be used.
7326
7327         .. note::
7328
7329            ``-native`` recipes are not installed into host paths like such
7330            as ``/usr``. Rather, these recipes are installed into
7331            :term:`STAGING_DIR_NATIVE`. When compiling ``-native`` recipes,
7332            standard build environment variables such as
7333            :term:`CPPFLAGS` and
7334            :term:`CFLAGS` are set up so that both host paths
7335            and :term:`STAGING_DIR_NATIVE` are searched for libraries and
7336            headers using, for example, GCC's ``-isystem`` option.
7337
7338            Thus, the emphasis is that the ``STAGING_DIR*`` variables
7339            should be viewed as input variables by tasks such as
7340            :ref:`ref-tasks-configure`,
7341            :ref:`ref-tasks-compile`, and
7342            :ref:`ref-tasks-install`. Having the real system
7343            root correspond to :term:`STAGING_DIR_HOST` makes conceptual sense
7344            for ``-native`` recipes, as they make use of host headers and
7345            libraries.
7346
7347   :term:`STAGING_DIR_NATIVE`
7348      Specifies the path to the sysroot directory used when building
7349      components that run on the build host itself.
7350
7351   :term:`STAGING_DIR_TARGET`
7352      Specifies the path to the sysroot used for the system for which the
7353      component generates code. For components that do not generate code,
7354      which is the majority, :term:`STAGING_DIR_TARGET` is set to match
7355      :term:`STAGING_DIR_HOST`.
7356
7357      Some recipes build binaries that can run on the target system but
7358      those binaries in turn generate code for another different system
7359      (e.g. cross-canadian recipes). Using terminology from GNU, the
7360      primary system is referred to as the "HOST" and the secondary, or
7361      different, system is referred to as the "TARGET". Thus, the binaries
7362      run on the "HOST" system and generate binaries for the "TARGET"
7363      system. The :term:`STAGING_DIR_HOST` variable points to the sysroot used
7364      for the "HOST" system, while :term:`STAGING_DIR_TARGET` points to the
7365      sysroot used for the "TARGET" system.
7366
7367   :term:`STAGING_ETCDIR_NATIVE`
7368      Specifies the path to the ``/etc`` subdirectory of the sysroot
7369      directory for the build host.
7370
7371   :term:`STAGING_EXECPREFIXDIR`
7372      Specifies the path to the ``/usr`` subdirectory of the sysroot
7373      directory for the target for which the current recipe is being built
7374      (:term:`STAGING_DIR_HOST`).
7375
7376   :term:`STAGING_INCDIR`
7377      Specifies the path to the ``/usr/include`` subdirectory of the
7378      sysroot directory for the target for which the current recipe being
7379      built (:term:`STAGING_DIR_HOST`).
7380
7381   :term:`STAGING_INCDIR_NATIVE`
7382      Specifies the path to the ``/usr/include`` subdirectory of the
7383      sysroot directory for the build host.
7384
7385   :term:`STAGING_KERNEL_BUILDDIR`
7386      Points to the directory containing the kernel build artifacts.
7387      Recipes building software that needs to access kernel build artifacts
7388      (e.g. ``systemtap-uprobes``) can look in the directory specified with
7389      the :term:`STAGING_KERNEL_BUILDDIR` variable to find these artifacts
7390      after the kernel has been built.
7391
7392   :term:`STAGING_KERNEL_DIR`
7393      The directory with kernel headers that are required to build
7394      out-of-tree modules.
7395
7396   :term:`STAGING_LIBDIR`
7397      Specifies the path to the ``/usr/lib`` subdirectory of the sysroot
7398      directory for the target for which the current recipe is being built
7399      (:term:`STAGING_DIR_HOST`).
7400
7401   :term:`STAGING_LIBDIR_NATIVE`
7402      Specifies the path to the ``/usr/lib`` subdirectory of the sysroot
7403      directory for the build host.
7404
7405   :term:`STAMP`
7406      Specifies the base path used to create recipe stamp files. The path
7407      to an actual stamp file is constructed by evaluating this string and
7408      then appending additional information. Currently, the default
7409      assignment for :term:`STAMP` as set in the ``meta/conf/bitbake.conf``
7410      file is::
7411
7412         STAMP = "${STAMPS_DIR}/${MULTIMACH_TARGET_SYS}/${PN}/${EXTENDPE}${PV}-${PR}"
7413
7414      For information on how BitBake uses stamp files to determine if a
7415      task should be rerun, see the
7416      ":ref:`overview-manual/concepts:stamp files and the rerunning of tasks`"
7417      section in the Yocto Project Overview and Concepts Manual.
7418
7419      See :term:`STAMPS_DIR`,
7420      :term:`MULTIMACH_TARGET_SYS`,
7421      :term:`PN`, :term:`EXTENDPE`,
7422      :term:`PV`, and :term:`PR` for related variable
7423      information.
7424
7425   :term:`STAMPS_DIR`
7426      Specifies the base directory in which the OpenEmbedded build system
7427      places stamps. The default directory is ``${TMPDIR}/stamps``.
7428
7429   :term:`STRIP`
7430      The minimal command and arguments to run ``strip``, which is used to
7431      strip symbols.
7432
7433   :term:`SUMMARY`
7434      The short (72 characters or less) summary of the binary package for
7435      packaging systems such as ``opkg``, ``rpm``, or ``dpkg``. By default,
7436      :term:`SUMMARY` is used to define the
7437      :term:`DESCRIPTION` variable if :term:`DESCRIPTION` is
7438      not set in the recipe.
7439
7440   :term:`SVNDIR`
7441      The directory in which files checked out of a Subversion system are
7442      stored.
7443
7444   :term:`SYSLINUX_DEFAULT_CONSOLE`
7445      Specifies the kernel boot default console. If you want to use a
7446      console other than the default, set this variable in your recipe as
7447      follows where "X" is the console number you want to use::
7448
7449         SYSLINUX_DEFAULT_CONSOLE = "console=ttyX"
7450
7451      The :ref:`syslinux <ref-classes-syslinux>` class initially sets
7452      this variable to null but then checks for a value later.
7453
7454   :term:`SYSLINUX_OPTS`
7455      Lists additional options to add to the syslinux file. You need to set
7456      this variable in your recipe. If you want to list multiple options,
7457      separate the options with a semicolon character (``;``).
7458
7459      The :ref:`syslinux <ref-classes-syslinux>` class uses this variable
7460      to create a set of options.
7461
7462   :term:`SYSLINUX_SERIAL`
7463      Specifies the alternate serial port or turns it off. To turn off
7464      serial, set this variable to an empty string in your recipe. The
7465      variable's default value is set in the
7466      :ref:`syslinux <ref-classes-syslinux>` class as follows::
7467
7468         SYSLINUX_SERIAL ?= "0 115200"
7469
7470      The class checks for and uses the variable as needed.
7471
7472   :term:`SYSLINUX_SERIAL_TTY`
7473      Specifies the alternate console=tty... kernel boot argument. The
7474      variable's default value is set in the
7475      :ref:`syslinux <ref-classes-syslinux>` class as follows::
7476
7477         SYSLINUX_SERIAL_TTY ?= "console=ttyS0,115200"
7478
7479      The class checks for and uses the variable as needed.
7480
7481   :term:`SYSLINUX_SPLASH`
7482      An ``.LSS`` file used as the background for the VGA boot menu when
7483      you use the boot menu. You need to set this variable in your recipe.
7484
7485      The :ref:`syslinux <ref-classes-syslinux>` class checks for this
7486      variable and if found, the OpenEmbedded build system installs the
7487      splash screen.
7488
7489   :term:`SYSROOT_DESTDIR`
7490      Points to the temporary directory under the work directory (default
7491      "``${``\ :term:`WORKDIR`\ ``}/sysroot-destdir``")
7492      where the files populated into the sysroot are assembled during the
7493      :ref:`ref-tasks-populate_sysroot` task.
7494
7495   :term:`SYSROOT_DIRS`
7496      Directories that are staged into the sysroot by the
7497      :ref:`ref-tasks-populate_sysroot` task. By
7498      default, the following directories are staged::
7499
7500         SYSROOT_DIRS = " \
7501             ${includedir} \
7502             ${libdir} \
7503             ${base_libdir} \
7504             ${nonarch_base_libdir} \
7505             ${datadir} \
7506             "
7507
7508   :term:`SYSROOT_DIRS_BLACKLIST`
7509      Directories that are not staged into the sysroot by the
7510      :ref:`ref-tasks-populate_sysroot` task. You
7511      can use this variable to exclude certain subdirectories of
7512      directories listed in :term:`SYSROOT_DIRS` from
7513      staging. By default, the following directories are not staged::
7514
7515         SYSROOT_DIRS_BLACKLIST = " \
7516             ${mandir} \
7517             ${docdir} \
7518             ${infodir} \
7519             ${datadir}/locale \
7520             ${datadir}/applications \
7521             ${datadir}/fonts \
7522             ${datadir}/pixmaps \
7523             "
7524
7525   :term:`SYSROOT_DIRS_NATIVE`
7526      Extra directories staged into the sysroot by the
7527      :ref:`ref-tasks-populate_sysroot` task for
7528      ``-native`` recipes, in addition to those specified in
7529      :term:`SYSROOT_DIRS`. By default, the following
7530      extra directories are staged::
7531
7532         SYSROOT_DIRS_NATIVE = " \
7533             ${bindir} \
7534             ${sbindir} \
7535             ${base_bindir} \
7536             ${base_sbindir} \
7537             ${libexecdir} \
7538             ${sysconfdir} \
7539             ${localstatedir} \
7540             "
7541
7542      .. note::
7543
7544         Programs built by ``-native`` recipes run directly from the sysroot
7545         (:term:`STAGING_DIR_NATIVE`), which is why additional directories
7546         containing program executables and supporting files need to be staged.
7547
7548   :term:`SYSROOT_PREPROCESS_FUNCS`
7549      A list of functions to execute after files are staged into the
7550      sysroot. These functions are usually used to apply additional
7551      processing on the staged files, or to stage additional files.
7552
7553   :term:`SYSTEMD_AUTO_ENABLE`
7554      When inheriting the :ref:`systemd <ref-classes-systemd>` class,
7555      this variable specifies whether the specified service in
7556      :term:`SYSTEMD_SERVICE` should start
7557      automatically or not. By default, the service is enabled to
7558      automatically start at boot time. The default setting is in the
7559      :ref:`systemd <ref-classes-systemd>` class as follows::
7560
7561         SYSTEMD_AUTO_ENABLE ??= "enable"
7562
7563      You can disable the service by setting the variable to "disable".
7564
7565   :term:`SYSTEMD_BOOT_CFG`
7566      When :term:`EFI_PROVIDER` is set to
7567      "systemd-boot", the :term:`SYSTEMD_BOOT_CFG` variable specifies the
7568      configuration file that should be used. By default, the
7569      :ref:`systemd-boot <ref-classes-systemd-boot>` class sets the
7570      :term:`SYSTEMD_BOOT_CFG` as follows::
7571
7572         SYSTEMD_BOOT_CFG ?= "${:term:`S`}/loader.conf"
7573
7574      For information on Systemd-boot, see the `Systemd-boot
7575      documentation <https://www.freedesktop.org/wiki/Software/systemd/systemd-boot/>`__.
7576
7577   :term:`SYSTEMD_BOOT_ENTRIES`
7578      When :term:`EFI_PROVIDER` is set to
7579      "systemd-boot", the :term:`SYSTEMD_BOOT_ENTRIES` variable specifies a
7580      list of entry files (``*.conf``) to install that contain one boot
7581      entry per file. By default, the
7582      :ref:`systemd-boot <ref-classes-systemd-boot>` class sets the
7583      :term:`SYSTEMD_BOOT_ENTRIES` as follows::
7584
7585          SYSTEMD_BOOT_ENTRIES ?= ""
7586
7587      For information on Systemd-boot, see the `Systemd-boot
7588      documentation <https://www.freedesktop.org/wiki/Software/systemd/systemd-boot/>`__.
7589
7590   :term:`SYSTEMD_BOOT_TIMEOUT`
7591      When :term:`EFI_PROVIDER` is set to
7592      "systemd-boot", the :term:`SYSTEMD_BOOT_TIMEOUT` variable specifies the
7593      boot menu timeout in seconds. By default, the
7594      :ref:`systemd-boot <ref-classes-systemd-boot>` class sets the
7595      :term:`SYSTEMD_BOOT_TIMEOUT` as follows::
7596
7597         SYSTEMD_BOOT_TIMEOUT ?= "10"
7598
7599      For information on Systemd-boot, see the `Systemd-boot
7600      documentation <https://www.freedesktop.org/wiki/Software/systemd/systemd-boot/>`__.
7601
7602   :term:`SYSTEMD_PACKAGES`
7603      When inheriting the :ref:`systemd <ref-classes-systemd>` class,
7604      this variable locates the systemd unit files when they are not found
7605      in the main recipe's package. By default, the :term:`SYSTEMD_PACKAGES`
7606      variable is set such that the systemd unit files are assumed to
7607      reside in the recipes main package::
7608
7609         SYSTEMD_PACKAGES ?= "${PN}"
7610
7611      If these unit files are not in this recipe's main package, you need
7612      to use :term:`SYSTEMD_PACKAGES` to list the package or packages in which
7613      the build system can find the systemd unit files.
7614
7615   :term:`SYSTEMD_SERVICE`
7616      When inheriting the :ref:`systemd <ref-classes-systemd>` class,
7617      this variable specifies the systemd service name for a package.
7618
7619      When you specify this file in your recipe, use a package name
7620      override to indicate the package to which the value applies. Here is
7621      an example from the connman recipe::
7622
7623         SYSTEMD_SERVICE:${PN} = "connman.service"
7624
7625   :term:`SYSVINIT_ENABLED_GETTYS`
7626      When using
7627      :ref:`SysVinit <dev-manual/common-tasks:enabling system services>`,
7628      specifies a space-separated list of the virtual terminals that should
7629      run a `getty <https://en.wikipedia.org/wiki/Getty_%28Unix%29>`__
7630      (allowing login), assuming :term:`USE_VT` is not set to
7631      "0".
7632
7633      The default value for :term:`SYSVINIT_ENABLED_GETTYS` is "1" (i.e. only
7634      run a getty on the first virtual terminal).
7635
7636   :term:`T`
7637      This variable points to a directory were BitBake places temporary
7638      files, which consist mostly of task logs and scripts, when building a
7639      particular recipe. The variable is typically set as follows::
7640
7641         T = "${WORKDIR}/temp"
7642
7643      The :term:`WORKDIR` is the directory into which
7644      BitBake unpacks and builds the recipe. The default ``bitbake.conf``
7645      file sets this variable.
7646
7647      The :term:`T` variable is not to be confused with the
7648      :term:`TMPDIR` variable, which points to the root of
7649      the directory tree where BitBake places the output of an entire
7650      build.
7651
7652   :term:`TARGET_ARCH`
7653      The target machine's architecture. The OpenEmbedded build system
7654      supports many architectures. Here is an example list of architectures
7655      supported. This list is by no means complete as the architecture is
7656      configurable:
7657
7658      - arm
7659      - i586
7660      - x86_64
7661      - powerpc
7662      - powerpc64
7663      - mips
7664      - mipsel
7665
7666      For additional information on machine architectures, see the
7667      :term:`TUNE_ARCH` variable.
7668
7669   :term:`TARGET_AS_ARCH`
7670      Specifies architecture-specific assembler flags for the target
7671      system. :term:`TARGET_AS_ARCH` is initialized from
7672      :term:`TUNE_ASARGS` by default in the BitBake
7673      configuration file (``meta/conf/bitbake.conf``)::
7674
7675         TARGET_AS_ARCH = "${TUNE_ASARGS}"
7676
7677   :term:`TARGET_CC_ARCH`
7678      Specifies architecture-specific C compiler flags for the target
7679      system. :term:`TARGET_CC_ARCH` is initialized from
7680      :term:`TUNE_CCARGS` by default.
7681
7682      .. note::
7683
7684         It is a common workaround to append :term:`LDFLAGS` to
7685         :term:`TARGET_CC_ARCH` in recipes that build software for the target that
7686         would not otherwise respect the exported :term:`LDFLAGS` variable.
7687
7688   :term:`TARGET_CC_KERNEL_ARCH`
7689      This is a specific kernel compiler flag for a CPU or Application
7690      Binary Interface (ABI) tune. The flag is used rarely and only for
7691      cases where a userspace :term:`TUNE_CCARGS` is not
7692      compatible with the kernel compilation. The :term:`TARGET_CC_KERNEL_ARCH`
7693      variable allows the kernel (and associated modules) to use a
7694      different configuration. See the
7695      ``meta/conf/machine/include/arm/feature-arm-thumb.inc`` file in the
7696      :term:`Source Directory` for an example.
7697
7698   :term:`TARGET_CFLAGS`
7699      Specifies the flags to pass to the C compiler when building for the
7700      target. When building in the target context,
7701      :term:`CFLAGS` is set to the value of this variable by
7702      default.
7703
7704      Additionally, the SDK's environment setup script sets the :term:`CFLAGS`
7705      variable in the environment to the :term:`TARGET_CFLAGS` value so that
7706      executables built using the SDK also have the flags applied.
7707
7708   :term:`TARGET_CPPFLAGS`
7709      Specifies the flags to pass to the C pre-processor (i.e. to both the
7710      C and the C++ compilers) when building for the target. When building
7711      in the target context, :term:`CPPFLAGS` is set to the
7712      value of this variable by default.
7713
7714      Additionally, the SDK's environment setup script sets the
7715      :term:`CPPFLAGS` variable in the environment to the :term:`TARGET_CPPFLAGS`
7716      value so that executables built using the SDK also have the flags
7717      applied.
7718
7719   :term:`TARGET_CXXFLAGS`
7720      Specifies the flags to pass to the C++ compiler when building for the
7721      target. When building in the target context,
7722      :term:`CXXFLAGS` is set to the value of this variable
7723      by default.
7724
7725      Additionally, the SDK's environment setup script sets the
7726      :term:`CXXFLAGS` variable in the environment to the :term:`TARGET_CXXFLAGS`
7727      value so that executables built using the SDK also have the flags
7728      applied.
7729
7730   :term:`TARGET_FPU`
7731      Specifies the method for handling FPU code. For FPU-less targets,
7732      which include most ARM CPUs, the variable must be set to "soft". If
7733      not, the kernel emulation gets used, which results in a performance
7734      penalty.
7735
7736   :term:`TARGET_LD_ARCH`
7737      Specifies architecture-specific linker flags for the target system.
7738      :term:`TARGET_LD_ARCH` is initialized from
7739      :term:`TUNE_LDARGS` by default in the BitBake
7740      configuration file (``meta/conf/bitbake.conf``)::
7741
7742         TARGET_LD_ARCH = "${TUNE_LDARGS}"
7743
7744   :term:`TARGET_LDFLAGS`
7745      Specifies the flags to pass to the linker when building for the
7746      target. When building in the target context,
7747      :term:`LDFLAGS` is set to the value of this variable
7748      by default.
7749
7750      Additionally, the SDK's environment setup script sets the
7751      :term:`LDFLAGS` variable in the environment to the
7752      :term:`TARGET_LDFLAGS` value so that executables built using the SDK also
7753      have the flags applied.
7754
7755   :term:`TARGET_OS`
7756      Specifies the target's operating system. The variable can be set to
7757      "linux" for glibc-based systems (GNU C Library) and to "linux-musl"
7758      for musl libc. For ARM/EABI targets, the possible values are
7759      "linux-gnueabi" and "linux-musleabi".
7760
7761   :term:`TARGET_PREFIX`
7762      Specifies the prefix used for the toolchain binary target tools.
7763
7764      Depending on the type of recipe and the build target,
7765      :term:`TARGET_PREFIX` is set as follows:
7766
7767      -  For recipes building for the target machine, the value is
7768         "${:term:`TARGET_SYS`}-".
7769
7770      -  For native recipes, the build system sets the variable to the
7771         value of :term:`BUILD_PREFIX`.
7772
7773      -  For native SDK recipes (``nativesdk``), the build system sets the
7774         variable to the value of :term:`SDK_PREFIX`.
7775
7776   :term:`TARGET_SYS`
7777      Specifies the system, including the architecture and the operating
7778      system, for which the build is occurring in the context of the
7779      current recipe.
7780
7781      The OpenEmbedded build system automatically sets this variable based
7782      on :term:`TARGET_ARCH`,
7783      :term:`TARGET_VENDOR`, and
7784      :term:`TARGET_OS` variables.
7785
7786      .. note::
7787
7788         You do not need to set the :term:`TARGET_SYS` variable yourself.
7789
7790      Consider these two examples:
7791
7792      -  Given a native recipe on a 32-bit, x86 machine running Linux, the
7793         value is "i686-linux".
7794
7795      -  Given a recipe being built for a little-endian, MIPS target
7796         running Linux, the value might be "mipsel-linux".
7797
7798   :term:`TARGET_VENDOR`
7799      Specifies the name of the target vendor.
7800
7801   :term:`TCLIBC`
7802      Specifies the GNU standard C library (``libc``) variant to use during
7803      the build process. This variable replaces ``POKYLIBC``, which is no
7804      longer supported.
7805
7806      You can select "glibc", "musl", "newlib", or "baremetal"
7807
7808   :term:`TCLIBCAPPEND`
7809      Specifies a suffix to be appended onto the
7810      :term:`TMPDIR` value. The suffix identifies the
7811      ``libc`` variant for building. When you are building for multiple
7812      variants with the same :term:`Build Directory`, this
7813      mechanism ensures that output for different ``libc`` variants is kept
7814      separate to avoid potential conflicts.
7815
7816      In the ``defaultsetup.conf`` file, the default value of
7817      :term:`TCLIBCAPPEND` is "-${TCLIBC}". However, distros such as poky,
7818      which normally only support one ``libc`` variant, set
7819      :term:`TCLIBCAPPEND` to "" in their distro configuration file resulting
7820      in no suffix being applied.
7821
7822   :term:`TCMODE`
7823      Specifies the toolchain selector. :term:`TCMODE` controls the
7824      characteristics of the generated packages and images by telling the
7825      OpenEmbedded build system which toolchain profile to use. By default,
7826      the OpenEmbedded build system builds its own internal toolchain. The
7827      variable's default value is "default", which uses that internal
7828      toolchain.
7829
7830      .. note::
7831
7832         If :term:`TCMODE` is set to a value other than "default", then it is your
7833         responsibility to ensure that the toolchain is compatible with the
7834         default toolchain. Using older or newer versions of these
7835         components might cause build problems. See the Release Notes for
7836         the Yocto Project release for the specific components with which
7837         the toolchain must be compatible. To access the Release Notes, go
7838         to the :yocto_home:`Downloads </software-overview/downloads>`
7839         page on the Yocto Project website and click on the "RELEASE
7840         INFORMATION" link for the appropriate release.
7841
7842      The :term:`TCMODE` variable is similar to :term:`TCLIBC`,
7843      which controls the variant of the GNU standard C library (``libc``)
7844      used during the build process: ``glibc`` or ``musl``.
7845
7846      With additional layers, it is possible to use a pre-compiled external
7847      toolchain. One example is the Sourcery G++ Toolchain. The support for
7848      this toolchain resides in the separate Mentor Graphics
7849      ``meta-sourcery`` layer at
7850      https://github.com/MentorEmbedded/meta-sourcery/.
7851
7852      The layer's ``README`` file contains information on how to use the
7853      Sourcery G++ Toolchain as an external toolchain. In summary, you must
7854      be sure to add the layer to your ``bblayers.conf`` file in front of
7855      the ``meta`` layer and then set the ``EXTERNAL_TOOLCHAIN`` variable
7856      in your ``local.conf`` file to the location in which you installed
7857      the toolchain.
7858
7859      The fundamentals used for this example apply to any external
7860      toolchain. You can use ``meta-sourcery`` as a template for adding
7861      support for other external toolchains.
7862
7863   :term:`TEST_EXPORT_DIR`
7864      The location the OpenEmbedded build system uses to export tests when
7865      the :term:`TEST_EXPORT_ONLY` variable is set
7866      to "1".
7867
7868      The :term:`TEST_EXPORT_DIR` variable defaults to
7869      ``"${TMPDIR}/testimage/${PN}"``.
7870
7871   :term:`TEST_EXPORT_ONLY`
7872      Specifies to export the tests only. Set this variable to "1" if you
7873      do not want to run the tests but you want them to be exported in a
7874      manner that you to run them outside of the build system.
7875
7876   :term:`TEST_LOG_DIR`
7877      Holds the SSH log and the boot log for QEMU machines. The
7878      :term:`TEST_LOG_DIR` variable defaults to ``"${WORKDIR}/testimage"``.
7879
7880      .. note::
7881
7882         Actual test results reside in the task log (``log.do_testimage``),
7883         which is in the ``${WORKDIR}/temp/`` directory.
7884
7885   :term:`TEST_POWERCONTROL_CMD`
7886      For automated hardware testing, specifies the command to use to
7887      control the power of the target machine under test. Typically, this
7888      command would point to a script that performs the appropriate action
7889      (e.g. interacting with a web-enabled power strip). The specified
7890      command should expect to receive as the last argument "off", "on" or
7891      "cycle" specifying to power off, on, or cycle (power off and then
7892      power on) the device, respectively.
7893
7894   :term:`TEST_POWERCONTROL_EXTRA_ARGS`
7895      For automated hardware testing, specifies additional arguments to
7896      pass through to the command specified in
7897      :term:`TEST_POWERCONTROL_CMD`. Setting
7898      :term:`TEST_POWERCONTROL_EXTRA_ARGS` is optional. You can use it if you
7899      wish, for example, to separate the machine-specific and
7900      non-machine-specific parts of the arguments.
7901
7902   :term:`TEST_QEMUBOOT_TIMEOUT`
7903      The time in seconds allowed for an image to boot before automated
7904      runtime tests begin to run against an image. The default timeout
7905      period to allow the boot process to reach the login prompt is 500
7906      seconds. You can specify a different value in the ``local.conf``
7907      file.
7908
7909      For more information on testing images, see the
7910      ":ref:`dev-manual/common-tasks:performing automated runtime testing`"
7911      section in the Yocto Project Development Tasks Manual.
7912
7913   :term:`TEST_SERIALCONTROL_CMD`
7914      For automated hardware testing, specifies the command to use to
7915      connect to the serial console of the target machine under test. This
7916      command simply needs to connect to the serial console and forward
7917      that connection to standard input and output as any normal terminal
7918      program does.
7919
7920      For example, to use the Picocom terminal program on serial device
7921      ``/dev/ttyUSB0`` at 115200bps, you would set the variable as follows::
7922
7923         TEST_SERIALCONTROL_CMD = "picocom /dev/ttyUSB0 -b 115200"
7924
7925   :term:`TEST_SERIALCONTROL_EXTRA_ARGS`
7926      For automated hardware testing, specifies additional arguments to
7927      pass through to the command specified in
7928      :term:`TEST_SERIALCONTROL_CMD`. Setting
7929      :term:`TEST_SERIALCONTROL_EXTRA_ARGS` is optional. You can use it if you
7930      wish, for example, to separate the machine-specific and
7931      non-machine-specific parts of the command.
7932
7933   :term:`TEST_SERVER_IP`
7934      The IP address of the build machine (host machine). This IP address
7935      is usually automatically detected. However, if detection fails, this
7936      variable needs to be set to the IP address of the build machine (i.e.
7937      where the build is taking place).
7938
7939      .. note::
7940
7941         The :term:`TEST_SERVER_IP` variable is only used for a small number of
7942         tests such as the "dnf" test suite, which needs to download packages
7943         from ``WORKDIR/oe-rootfs-repo``.
7944
7945   :term:`TEST_SUITES`
7946      An ordered list of tests (modules) to run against an image when
7947      performing automated runtime testing.
7948
7949      The OpenEmbedded build system provides a core set of tests that can
7950      be used against images.
7951
7952      .. note::
7953
7954         Currently, there is only support for running these tests under
7955         QEMU.
7956
7957      Tests include ``ping``, ``ssh``, ``df`` among others. You can add
7958      your own tests to the list of tests by appending :term:`TEST_SUITES` as
7959      follows::
7960
7961         TEST_SUITES:append = " mytest"
7962
7963      Alternatively, you can
7964      provide the "auto" option to have all applicable tests run against
7965      the image.
7966      ::
7967
7968         TEST_SUITES:append = " auto"
7969
7970      Using this option causes the
7971      build system to automatically run tests that are applicable to the
7972      image. Tests that are not applicable are skipped.
7973
7974      The order in which tests are run is important. Tests that depend on
7975      another test must appear later in the list than the test on which
7976      they depend. For example, if you append the list of tests with two
7977      tests (``test_A`` and ``test_B``) where ``test_B`` is dependent on
7978      ``test_A``, then you must order the tests as follows::
7979
7980         TEST_SUITES = "test_A test_B"
7981
7982      For more information on testing images, see the
7983      ":ref:`dev-manual/common-tasks:performing automated runtime testing`"
7984      section in the Yocto Project Development Tasks Manual.
7985
7986   :term:`TEST_TARGET`
7987      Specifies the target controller to use when running tests against a
7988      test image. The default controller to use is "qemu"::
7989
7990         TEST_TARGET = "qemu"
7991
7992      A target controller is a class that defines how an image gets
7993      deployed on a target and how a target is started. A layer can extend
7994      the controllers by adding a module in the layer's
7995      ``/lib/oeqa/controllers`` directory and by inheriting the
7996      ``BaseTarget`` class, which is an abstract class that cannot be used
7997      as a value of :term:`TEST_TARGET`.
7998
7999      You can provide the following arguments with :term:`TEST_TARGET`:
8000
8001      -  *"qemu":* Boots a QEMU image and runs the tests. See the
8002         ":ref:`dev-manual/common-tasks:enabling runtime tests on qemu`" section
8003         in the Yocto Project Development Tasks Manual for more
8004         information.
8005
8006      -  *"simpleremote":* Runs the tests on target hardware that is
8007         already up and running. The hardware can be on the network or it
8008         can be a device running an image on QEMU. You must also set
8009         :term:`TEST_TARGET_IP` when you use
8010         "simpleremote".
8011
8012         .. note::
8013
8014            This argument is defined in
8015            ``meta/lib/oeqa/controllers/simpleremote.py``.
8016
8017      For information on running tests on hardware, see the
8018      ":ref:`dev-manual/common-tasks:enabling runtime tests on hardware`"
8019      section in the Yocto Project Development Tasks Manual.
8020
8021   :term:`TEST_TARGET_IP`
8022      The IP address of your hardware under test. The :term:`TEST_TARGET_IP`
8023      variable has no effect when :term:`TEST_TARGET` is
8024      set to "qemu".
8025
8026      When you specify the IP address, you can also include a port. Here is
8027      an example::
8028
8029         TEST_TARGET_IP = "192.168.1.4:2201"
8030
8031      Specifying a port is
8032      useful when SSH is started on a non-standard port or in cases when
8033      your hardware under test is behind a firewall or network that is not
8034      directly accessible from your host and you need to do port address
8035      translation.
8036
8037   :term:`TESTIMAGE_AUTO`
8038      Automatically runs the series of automated tests for images when an
8039      image is successfully built. Setting :term:`TESTIMAGE_AUTO` to "1" causes
8040      any image that successfully builds to automatically boot under QEMU.
8041      Using the variable also adds in dependencies so that any SDK for
8042      which testing is requested is automatically built first.
8043
8044      These tests are written in Python making use of the ``unittest``
8045      module, and the majority of them run commands on the target system
8046      over ``ssh``. You can set this variable to "1" in your ``local.conf``
8047      file in the :term:`Build Directory` to have the
8048      OpenEmbedded build system automatically run these tests after an
8049      image successfully builds:
8050
8051         TESTIMAGE_AUTO = "1"
8052
8053      For more information
8054      on enabling, running, and writing these tests, see the
8055      ":ref:`dev-manual/common-tasks:performing automated runtime testing`"
8056      section in the Yocto Project Development Tasks Manual and the
8057      ":ref:`testimage*.bbclass <ref-classes-testimage*>`" section.
8058
8059   :term:`THISDIR`
8060      The directory in which the file BitBake is currently parsing is
8061      located. Do not manually set this variable.
8062
8063   :term:`TIME`
8064      The time the build was started. Times appear using the hour, minute,
8065      and second (HMS) format (e.g. "140159" for one minute and fifty-nine
8066      seconds past 1400 hours).
8067
8068   :term:`TMPDIR`
8069      This variable is the base directory the OpenEmbedded build system
8070      uses for all build output and intermediate files (other than the
8071      shared state cache). By default, the :term:`TMPDIR` variable points to
8072      ``tmp`` within the :term:`Build Directory`.
8073
8074      If you want to establish this directory in a location other than the
8075      default, you can uncomment and edit the following statement in the
8076      ``conf/local.conf`` file in the :term:`Source Directory`::
8077
8078         #TMPDIR = "${TOPDIR}/tmp"
8079
8080      An example use for this scenario is to set :term:`TMPDIR` to a local disk,
8081      which does not use NFS, while having the Build Directory use NFS.
8082
8083      The filesystem used by :term:`TMPDIR` must have standard filesystem
8084      semantics (i.e. mixed-case files are unique, POSIX file locking, and
8085      persistent inodes). Due to various issues with NFS and bugs in some
8086      implementations, NFS does not meet this minimum requirement.
8087      Consequently, :term:`TMPDIR` cannot be on NFS.
8088
8089   :term:`TOOLCHAIN_HOST_TASK`
8090      This variable lists packages the OpenEmbedded build system uses when
8091      building an SDK, which contains a cross-development environment. The
8092      packages specified by this variable are part of the toolchain set
8093      that runs on the :term:`SDKMACHINE`, and each
8094      package should usually have the prefix ``nativesdk-``. For example,
8095      consider the following command when building an SDK::
8096
8097         $ bitbake -c populate_sdk imagename
8098
8099      In this case, a default list of packages is
8100      set in this variable, but you can add additional packages to the
8101      list. See the
8102      ":ref:`sdk-manual/appendix-customizing-standard:adding individual packages to the standard sdk`" section
8103      in the Yocto Project Application Development and the Extensible
8104      Software Development Kit (eSDK) manual for more information.
8105
8106      For background information on cross-development toolchains in the
8107      Yocto Project development environment, see the
8108      ":ref:`sdk-manual/intro:the cross-development toolchain`"
8109      section in the Yocto Project Overview and Concepts Manual. For
8110      information on setting up a cross-development environment, see the
8111      :doc:`/sdk-manual/index` manual.
8112
8113   :term:`TOOLCHAIN_OUTPUTNAME`
8114      This variable defines the name used for the toolchain output. The
8115      :ref:`populate_sdk_base <ref-classes-populate-sdk-*>` class sets
8116      the :term:`TOOLCHAIN_OUTPUTNAME` variable as follows::
8117
8118         TOOLCHAIN_OUTPUTNAME ?= "${SDK_NAME}-toolchain-${SDK_VERSION}"
8119
8120      See
8121      the :term:`SDK_NAME` and
8122      :term:`SDK_VERSION` variables for additional
8123      information.
8124
8125   :term:`TOOLCHAIN_TARGET_TASK`
8126      This variable lists packages the OpenEmbedded build system uses when
8127      it creates the target part of an SDK (i.e. the part built for the
8128      target hardware), which includes libraries and headers. Use this
8129      variable to add individual packages to the part of the SDK that runs
8130      on the target. See the
8131      ":ref:`sdk-manual/appendix-customizing-standard:adding individual packages to the standard sdk`" section
8132      in the Yocto Project Application Development and the Extensible
8133      Software Development Kit (eSDK) manual for more information.
8134
8135      For background information on cross-development toolchains in the
8136      Yocto Project development environment, see the
8137      ":ref:`sdk-manual/intro:the cross-development toolchain`"
8138      section in the Yocto Project Overview and Concepts Manual. For
8139      information on setting up a cross-development environment, see the
8140      :doc:`/sdk-manual/index` manual.
8141
8142   :term:`TOPDIR`
8143      The top-level :term:`Build Directory`. BitBake
8144      automatically sets this variable when you initialize your build
8145      environment using :ref:`structure-core-script`.
8146
8147   :term:`TRANSLATED_TARGET_ARCH`
8148      A sanitized version of :term:`TARGET_ARCH`. This
8149      variable is used where the architecture is needed in a value where
8150      underscores are not allowed, for example within package filenames. In
8151      this case, dash characters replace any underscore characters used in
8152      :term:`TARGET_ARCH`.
8153
8154      Do not edit this variable.
8155
8156   :term:`TUNE_ARCH`
8157      The GNU canonical architecture for a specific architecture (i.e.
8158      ``arm``, ``armeb``, ``mips``, ``mips64``, and so forth). BitBake uses
8159      this value to setup configuration.
8160
8161      :term:`TUNE_ARCH` definitions are specific to a given architecture. The
8162      definitions can be a single static definition, or can be dynamically
8163      adjusted. You can see details for a given CPU family by looking at
8164      the architecture's ``README`` file. For example, the
8165      ``meta/conf/machine/include/mips/README`` file in the
8166      :term:`Source Directory` provides information for
8167      :term:`TUNE_ARCH` specific to the ``mips`` architecture.
8168
8169      :term:`TUNE_ARCH` is tied closely to
8170      :term:`TARGET_ARCH`, which defines the target
8171      machine's architecture. The BitBake configuration file
8172      (``meta/conf/bitbake.conf``) sets :term:`TARGET_ARCH` as follows::
8173
8174         TARGET_ARCH = "${TUNE_ARCH}"
8175
8176      The following list, which is by no means complete since architectures
8177      are configurable, shows supported machine architectures:
8178
8179      - arm
8180      - i586
8181      - x86_64
8182      - powerpc
8183      - powerpc64
8184      - mips
8185      - mipsel
8186
8187   :term:`TUNE_ASARGS`
8188      Specifies architecture-specific assembler flags for the target
8189      system. The set of flags is based on the selected tune features.
8190      :term:`TUNE_ASARGS` is set using the tune include files, which are
8191      typically under ``meta/conf/machine/include/`` and are influenced
8192      through :term:`TUNE_FEATURES`. For example, the
8193      ``meta/conf/machine/include/x86/arch-x86.inc`` file defines the flags
8194      for the x86 architecture as follows::
8195
8196         TUNE_ASARGS += "${@bb.utils.contains("TUNE_FEATURES", "mx32", "-x32", "", d)}"
8197
8198      .. note::
8199
8200         Board Support Packages (BSPs) select the tune. The selected tune,
8201         in turn, affects the tune variables themselves (i.e. the tune can
8202         supply its own set of flags).
8203
8204   :term:`TUNE_CCARGS`
8205      Specifies architecture-specific C compiler flags for the target
8206      system. The set of flags is based on the selected tune features.
8207      :term:`TUNE_CCARGS` is set using the tune include files, which are
8208      typically under ``meta/conf/machine/include/`` and are influenced
8209      through :term:`TUNE_FEATURES`.
8210
8211      .. note::
8212
8213         Board Support Packages (BSPs) select the tune. The selected tune,
8214         in turn, affects the tune variables themselves (i.e. the tune can
8215         supply its own set of flags).
8216
8217   :term:`TUNE_FEATURES`
8218      Features used to "tune" a compiler for optimal use given a specific
8219      processor. The features are defined within the tune files and allow
8220      arguments (i.e. ``TUNE_*ARGS``) to be dynamically generated based on
8221      the features.
8222
8223      The OpenEmbedded build system verifies the features to be sure they
8224      are not conflicting and that they are supported.
8225
8226      The BitBake configuration file (``meta/conf/bitbake.conf``) defines
8227      :term:`TUNE_FEATURES` as follows::
8228
8229         TUNE_FEATURES ??= "${TUNE_FEATURES:tune-${DEFAULTTUNE}}"
8230
8231      See the :term:`DEFAULTTUNE` variable for more information.
8232
8233   :term:`TUNE_LDARGS`
8234      Specifies architecture-specific linker flags for the target system.
8235      The set of flags is based on the selected tune features.
8236      :term:`TUNE_LDARGS` is set using the tune include files, which are
8237      typically under ``meta/conf/machine/include/`` and are influenced
8238      through :term:`TUNE_FEATURES`. For example, the
8239      ``meta/conf/machine/include/x86/arch-x86.inc`` file defines the flags
8240      for the x86 architecture as follows::
8241
8242         TUNE_LDARGS += "${@bb.utils.contains("TUNE_FEATURES", "mx32", "-m elf32_x86_64", "", d)}"
8243
8244      .. note::
8245
8246         Board Support Packages (BSPs) select the tune. The selected tune,
8247         in turn, affects the tune variables themselves (i.e. the tune can
8248         supply its own set of flags).
8249
8250   :term:`TUNE_PKGARCH`
8251      The package architecture understood by the packaging system to define
8252      the architecture, ABI, and tuning of output packages. The specific
8253      tune is defined using the "_tune" override as follows::
8254
8255         TUNE_PKGARCH:tune-tune = "tune"
8256
8257      These tune-specific package architectures are defined in the machine
8258      include files. Here is an example of the "core2-32" tuning as used in
8259      the ``meta/conf/machine/include/tune-core2.inc`` file::
8260
8261         TUNE_PKGARCH:tune-core2-32 = "core2-32"
8262
8263   :term:`TUNEABI`
8264      An underlying Application Binary Interface (ABI) used by a particular
8265      tuning in a given toolchain layer. Providers that use prebuilt
8266      libraries can use the :term:`TUNEABI`,
8267      :term:`TUNEABI_OVERRIDE`, and
8268      :term:`TUNEABI_WHITELIST` variables to check
8269      compatibility of tunings against their selection of libraries.
8270
8271      If :term:`TUNEABI` is undefined, then every tuning is allowed. See the
8272      :ref:`sanity <ref-classes-sanity>` class to see how the variable is
8273      used.
8274
8275   :term:`TUNEABI_OVERRIDE`
8276      If set, the OpenEmbedded system ignores the
8277      :term:`TUNEABI_WHITELIST` variable.
8278      Providers that use prebuilt libraries can use the
8279      :term:`TUNEABI_OVERRIDE`, :term:`TUNEABI_WHITELIST`, and
8280      :term:`TUNEABI` variables to check compatibility of a
8281      tuning against their selection of libraries.
8282
8283      See the :ref:`sanity <ref-classes-sanity>` class to see how the
8284      variable is used.
8285
8286   :term:`TUNEABI_WHITELIST`
8287      A whitelist of permissible :term:`TUNEABI` values. If
8288      :term:`TUNEABI_WHITELIST` is not set, all tunes are allowed. Providers
8289      that use prebuilt libraries can use the :term:`TUNEABI_WHITELIST`,
8290      :term:`TUNEABI_OVERRIDE`, and :term:`TUNEABI`
8291      variables to check compatibility of a tuning against their selection
8292      of libraries.
8293
8294      See the :ref:`sanity <ref-classes-sanity>` class to see how the
8295      variable is used.
8296
8297   :term:`TUNECONFLICTS[feature]`
8298      Specifies CPU or Application Binary Interface (ABI) tuning features
8299      that conflict with feature.
8300
8301      Known tuning conflicts are specified in the machine include files in
8302      the :term:`Source Directory`. Here is an example from
8303      the ``meta/conf/machine/include/mips/arch-mips.inc`` include file
8304      that lists the "o32" and "n64" features as conflicting with the "n32"
8305      feature::
8306
8307         TUNECONFLICTS[n32] = "o32 n64"
8308
8309   :term:`TUNEVALID[feature]`
8310      Specifies a valid CPU or Application Binary Interface (ABI) tuning
8311      feature. The specified feature is stored as a flag. Valid features
8312      are specified in the machine include files (e.g.
8313      ``meta/conf/machine/include/arm/arch-arm.inc``). Here is an example
8314      from that file::
8315
8316         TUNEVALID[bigendian] = "Enable big-endian mode."
8317
8318      See the machine include files in the :term:`Source Directory`
8319      for these features.
8320
8321   :term:`UBOOT_CONFIG`
8322      Configures the :term:`UBOOT_MACHINE` and can
8323      also define :term:`IMAGE_FSTYPES` for individual
8324      cases.
8325
8326      Following is an example from the ``meta-fsl-arm`` layer. ::
8327
8328         UBOOT_CONFIG ??= "sd"
8329         UBOOT_CONFIG[sd] = "mx6qsabreauto_config,sdcard"
8330         UBOOT_CONFIG[eimnor] = "mx6qsabreauto_eimnor_config"
8331         UBOOT_CONFIG[nand] = "mx6qsabreauto_nand_config,ubifs"
8332         UBOOT_CONFIG[spinor] = "mx6qsabreauto_spinor_config"
8333
8334      In this example, "sd" is selected as the configuration of the possible four for the
8335      :term:`UBOOT_MACHINE`. The "sd" configuration defines
8336      "mx6qsabreauto_config" as the value for :term:`UBOOT_MACHINE`, while the
8337      "sdcard" specifies the :term:`IMAGE_FSTYPES` to use for the U-Boot image.
8338
8339      For more information on how the :term:`UBOOT_CONFIG` is handled, see the
8340      :ref:`uboot-config <ref-classes-uboot-config>`
8341      class.
8342
8343   :term:`UBOOT_DTB_LOADADDRESS`
8344      Specifies the load address for the dtb image used by U-Boot. During FIT
8345      image creation, the :term:`UBOOT_DTB_LOADADDRESS` variable is used in
8346      :ref:`kernel-fitimage <ref-classes-kernel-fitimage>` class to specify
8347      the load address to be used in
8348      creating the dtb sections of Image Tree Source for the FIT image.
8349
8350   :term:`UBOOT_DTBO_LOADADDRESS`
8351      Specifies the load address for the dtbo image used by U-Boot.  During FIT
8352      image creation, the :term:`UBOOT_DTBO_LOADADDRESS` variable is used in
8353      :ref:`kernel-fitimage <ref-classes-kernel-fitimage>` class to specify the load address to be used in
8354      creating the dtbo sections of Image Tree Source for the FIT image.
8355
8356   :term:`UBOOT_ENTRYPOINT`
8357      Specifies the entry point for the U-Boot image. During U-Boot image
8358      creation, the :term:`UBOOT_ENTRYPOINT` variable is passed as a
8359      command-line parameter to the ``uboot-mkimage`` utility.
8360
8361   :term:`UBOOT_LOADADDRESS`
8362      Specifies the load address for the U-Boot image. During U-Boot image
8363      creation, the :term:`UBOOT_LOADADDRESS` variable is passed as a
8364      command-line parameter to the ``uboot-mkimage`` utility.
8365
8366   :term:`UBOOT_LOCALVERSION`
8367      Appends a string to the name of the local version of the U-Boot
8368      image. For example, assuming the version of the U-Boot image built
8369      was "2013.10", the full version string reported by U-Boot would be
8370      "2013.10-yocto" given the following statement::
8371
8372         UBOOT_LOCALVERSION = "-yocto"
8373
8374   :term:`UBOOT_MACHINE`
8375      Specifies the value passed on the ``make`` command line when building
8376      a U-Boot image. The value indicates the target platform
8377      configuration. You typically set this variable from the machine
8378      configuration file (i.e. ``conf/machine/machine_name.conf``).
8379
8380      Please see the "Selection of Processor Architecture and Board Type"
8381      section in the U-Boot README for valid values for this variable.
8382
8383   :term:`UBOOT_MAKE_TARGET`
8384      Specifies the target called in the ``Makefile``. The default target
8385      is "all".
8386
8387   :term:`UBOOT_MKIMAGE`
8388      Specifies the name of the mkimage command as used by the
8389      :ref:`kernel-fitimage <ref-classes-kernel-fitimage>` class to assemble
8390      the FIT image. This can be used to substitute an alternative command, wrapper
8391      script or function if desired. The default is "uboot-mkimage".
8392
8393   :term:`UBOOT_MKIMAGE_DTCOPTS`
8394      Options for the device tree compiler passed to mkimage '-D'
8395      feature while creating FIT image in :ref:`kernel-fitimage <ref-classes-kernel-fitimage>` class.
8396      If :term:`UBOOT_MKIMAGE_DTCOPTS` is not set then kernel-fitimage will not
8397      pass the ``-D`` option to mkimage.
8398
8399   :term:`UBOOT_MKIMAGE_SIGN`
8400      Specifies the name of the mkimage command as used by the
8401      :ref:`kernel-fitimage <ref-classes-kernel-fitimage>` class to sign
8402      the FIT image after it has been assembled (if enabled). This can be used
8403      to substitute an alternative command, wrapper script or function if
8404      desired. The default is "${:term:`UBOOT_MKIMAGE`}".
8405
8406   :term:`UBOOT_MKIMAGE_SIGN_ARGS`
8407      Optionally specifies additional arguments for the
8408      :ref:`kernel-fitimage <ref-classes-kernel-fitimage>` class to pass to the
8409      mkimage command when signing the FIT image.
8410
8411   :term:`UBOOT_RD_ENTRYPOINT`
8412      Specifies the entrypoint for the RAM disk image.
8413      During FIT image creation, the
8414      :term:`UBOOT_RD_ENTRYPOINT` variable is used
8415      in :ref:`kernel-fitimage <ref-classes-kernel-fitimage>` class to specify the
8416      entrypoint to be used in creating the Image Tree Source for
8417      the FIT image.
8418
8419   :term:`UBOOT_RD_LOADADDRESS`
8420      Specifies the load address for the RAM disk image.
8421      During FIT image creation, the
8422      :term:`UBOOT_RD_LOADADDRESS` variable is used
8423      in :ref:`kernel-fitimage <ref-classes-kernel-fitimage>` class to specify the
8424      load address to be used in creating the Image Tree Source for
8425      the FIT image.
8426
8427   :term:`UBOOT_SIGN_ENABLE`
8428      Enable signing of FIT image. The default value is "0".
8429
8430   :term:`UBOOT_SIGN_KEYDIR`
8431      Location of the directory containing the RSA key and
8432      certificate used for signing FIT image.
8433
8434   :term:`UBOOT_SIGN_KEYNAME`
8435      The name of keys used for signing U-Boot FIT image stored in
8436      :term:`UBOOT_SIGN_KEYDIR` directory. For e.g. dev.key key and dev.crt
8437      certificate stored in :term:`UBOOT_SIGN_KEYDIR` directory will have
8438      :term:`UBOOT_SIGN_KEYNAME` set to "dev".
8439
8440   :term:`UBOOT_SUFFIX`
8441      Points to the generated U-Boot extension. For example, ``u-boot.sb``
8442      has a ``.sb`` extension.
8443
8444      The default U-Boot extension is ``.bin``
8445
8446   :term:`UBOOT_TARGET`
8447      Specifies the target used for building U-Boot. The target is passed
8448      directly as part of the "make" command (e.g. SPL and AIS). If you do
8449      not specifically set this variable, the OpenEmbedded build process
8450      passes and uses "all" for the target during the U-Boot building
8451      process.
8452
8453   :term:`UNKNOWN_CONFIGURE_WHITELIST`
8454      Specifies a list of options that, if reported by the configure script
8455      as being invalid, should not generate a warning during the
8456      :ref:`ref-tasks-configure` task. Normally, invalid
8457      configure options are simply not passed to the configure script (e.g.
8458      should be removed from :term:`EXTRA_OECONF` or
8459      :term:`PACKAGECONFIG_CONFARGS`).
8460      However, there are common options that are passed to all
8461      configure scripts at a class level, but might not be valid for some
8462      configure scripts. Therefore warnings about these options are useless.
8463      For these cases, the options are added to :term:`UNKNOWN_CONFIGURE_WHITELIST`.
8464
8465      The configure arguments check that uses
8466      :term:`UNKNOWN_CONFIGURE_WHITELIST` is part of the
8467      :ref:`insane <ref-classes-insane>` class and is only enabled if the
8468      recipe inherits the :ref:`autotools <ref-classes-autotools>` class.
8469
8470   :term:`UPDATERCPN`
8471      For recipes inheriting the
8472      :ref:`update-rc.d <ref-classes-update-rc.d>` class, :term:`UPDATERCPN`
8473      specifies the package that contains the initscript that is enabled.
8474
8475      The default value is "${PN}". Given that almost all recipes that
8476      install initscripts package them in the main package for the recipe,
8477      you rarely need to set this variable in individual recipes.
8478
8479   :term:`UPSTREAM_CHECK_GITTAGREGEX`
8480      You can perform a per-recipe check for what the latest upstream
8481      source code version is by calling ``bitbake -c checkpkg`` recipe. If
8482      the recipe source code is provided from Git repositories, the
8483      OpenEmbedded build system determines the latest upstream version by
8484      picking the latest tag from the list of all repository tags.
8485
8486      You can use the :term:`UPSTREAM_CHECK_GITTAGREGEX` variable to provide a
8487      regular expression to filter only the relevant tags should the
8488      default filter not work correctly.
8489      ::
8490
8491         UPSTREAM_CHECK_GITTAGREGEX = "git_tag_regex"
8492
8493   :term:`UPSTREAM_CHECK_REGEX`
8494      Use the :term:`UPSTREAM_CHECK_REGEX` variable to specify a different
8495      regular expression instead of the default one when the package
8496      checking system is parsing the page found using
8497      :term:`UPSTREAM_CHECK_URI`.
8498      ::
8499
8500         UPSTREAM_CHECK_REGEX = "package_regex"
8501
8502   :term:`UPSTREAM_CHECK_URI`
8503      You can perform a per-recipe check for what the latest upstream
8504      source code version is by calling ``bitbake -c checkpkg`` recipe. If
8505      the source code is provided from tarballs, the latest version is
8506      determined by fetching the directory listing where the tarball is and
8507      attempting to find a later tarball. When this approach does not work,
8508      you can use :term:`UPSTREAM_CHECK_URI` to provide a different URI that
8509      contains the link to the latest tarball.
8510      ::
8511
8512         UPSTREAM_CHECK_URI = "recipe_url"
8513
8514   :term:`USE_DEVFS`
8515      Determines if ``devtmpfs`` is used for ``/dev`` population. The
8516      default value used for :term:`USE_DEVFS` is "1" when no value is
8517      specifically set. Typically, you would set :term:`USE_DEVFS` to "0" for a
8518      statically populated ``/dev`` directory.
8519
8520      See the ":ref:`dev-manual/common-tasks:selecting a device manager`" section in
8521      the Yocto Project Development Tasks Manual for information on how to
8522      use this variable.
8523
8524   :term:`USE_VT`
8525      When using
8526      :ref:`SysVinit <dev-manual/common-tasks:enabling system services>`,
8527      determines whether or not to run a
8528      `getty <https://en.wikipedia.org/wiki/Getty_%28Unix%29>`__ on any
8529      virtual terminals in order to enable logging in through those
8530      terminals.
8531
8532      The default value used for :term:`USE_VT` is "1" when no default value is
8533      specifically set. Typically, you would set :term:`USE_VT` to "0" in the
8534      machine configuration file for machines that do not have a graphical
8535      display attached and therefore do not need virtual terminal
8536      functionality.
8537
8538   :term:`USER_CLASSES`
8539      A list of classes to globally inherit. These classes are used by the
8540      OpenEmbedded build system to enable extra features (e.g.
8541      ``buildstats``, ``image-prelink``, and so forth).
8542
8543      The default list is set in your ``local.conf`` file::
8544
8545         USER_CLASSES ?= "buildstats image-prelink"
8546
8547      For more information, see
8548      ``meta-poky/conf/local.conf.sample`` in the :term:`Source Directory`.
8549
8550   :term:`USERADD_ERROR_DYNAMIC`
8551      If set to ``error``, forces the OpenEmbedded build system to produce
8552      an error if the user identification (``uid``) and group
8553      identification (``gid``) values are not defined in any of the files
8554      listed in :term:`USERADD_UID_TABLES` and
8555      :term:`USERADD_GID_TABLES`. If set to
8556      ``warn``, a warning will be issued instead.
8557
8558      The default behavior for the build system is to dynamically apply
8559      ``uid`` and ``gid`` values. Consequently, the
8560      :term:`USERADD_ERROR_DYNAMIC` variable is by default not set. If you plan
8561      on using statically assigned ``gid`` and ``uid`` values, you should
8562      set the :term:`USERADD_ERROR_DYNAMIC` variable in your ``local.conf``
8563      file as follows::
8564
8565         USERADD_ERROR_DYNAMIC = "error"
8566
8567      Overriding the
8568      default behavior implies you are going to also take steps to set
8569      static ``uid`` and ``gid`` values through use of the
8570      :term:`USERADDEXTENSION`,
8571      :term:`USERADD_UID_TABLES`, and
8572      :term:`USERADD_GID_TABLES` variables.
8573
8574      .. note::
8575
8576         There is a difference in behavior between setting
8577         :term:`USERADD_ERROR_DYNAMIC` to ``error`` and setting it to ``warn``.
8578         When it is set to ``warn``, the build system will report a warning for
8579         every undefined ``uid`` and ``gid`` in any recipe. But when it is set
8580         to ``error``, it will only report errors for recipes that are actually
8581         built.
8582         This saves you from having to add static IDs for recipes that you
8583         know will never be built.
8584
8585   :term:`USERADD_GID_TABLES`
8586      Specifies a password file to use for obtaining static group
8587      identification (``gid``) values when the OpenEmbedded build system
8588      adds a group to the system during package installation.
8589
8590      When applying static group identification (``gid``) values, the
8591      OpenEmbedded build system looks in :term:`BBPATH` for a
8592      ``files/group`` file and then applies those ``uid`` values. Set the
8593      variable as follows in your ``local.conf`` file::
8594
8595
8596         USERADD_GID_TABLES = "files/group"
8597
8598      .. note::
8599
8600         Setting the :term:`USERADDEXTENSION` variable to "useradd-staticids"
8601         causes the build system to use static ``gid`` values.
8602
8603   :term:`USERADD_PACKAGES`
8604      When inheriting the :ref:`useradd <ref-classes-useradd>` class,
8605      this variable specifies the individual packages within the recipe
8606      that require users and/or groups to be added.
8607
8608      You must set this variable if the recipe inherits the class. For
8609      example, the following enables adding a user for the main package in
8610      a recipe::
8611
8612         USERADD_PACKAGES = "${PN}"
8613
8614      .. note::
8615
8616         It follows that if you are going to use the :term:`USERADD_PACKAGES`
8617         variable, you need to set one or more of the :term:`USERADD_PARAM`,
8618         :term:`GROUPADD_PARAM`, or :term:`GROUPMEMS_PARAM` variables.
8619
8620   :term:`USERADD_PARAM`
8621      When inheriting the :ref:`useradd <ref-classes-useradd>` class,
8622      this variable specifies for a package what parameters should pass to
8623      the ``useradd`` command if you add a user to the system when the
8624      package is installed.
8625
8626      Here is an example from the ``dbus`` recipe::
8627
8628         USERADD_PARAM:${PN} = "--system --home ${localstatedir}/lib/dbus \
8629                                --no-create-home --shell /bin/false \
8630                                --user-group messagebus"
8631
8632      For information on the
8633      standard Linux shell command ``useradd``, see
8634      https://linux.die.net/man/8/useradd.
8635
8636   :term:`USERADD_UID_TABLES`
8637      Specifies a password file to use for obtaining static user
8638      identification (``uid``) values when the OpenEmbedded build system
8639      adds a user to the system during package installation.
8640
8641      When applying static user identification (``uid``) values, the
8642      OpenEmbedded build system looks in :term:`BBPATH` for a
8643      ``files/passwd`` file and then applies those ``uid`` values. Set the
8644      variable as follows in your ``local.conf`` file::
8645
8646         USERADD_UID_TABLES = "files/passwd"
8647
8648      .. note::
8649
8650         Setting the :term:`USERADDEXTENSION` variable to "useradd-staticids"
8651         causes the build system to use static ``uid`` values.
8652
8653   :term:`USERADDEXTENSION`
8654      When set to "useradd-staticids", causes the OpenEmbedded build system
8655      to base all user and group additions on a static ``passwd`` and
8656      ``group`` files found in :term:`BBPATH`.
8657
8658      To use static user identification (``uid``) and group identification
8659      (``gid``) values, set the variable as follows in your ``local.conf``
8660      file: USERADDEXTENSION = "useradd-staticids"
8661
8662      .. note::
8663
8664         Setting this variable to use static ``uid`` and ``gid``
8665         values causes the OpenEmbedded build system to employ the
8666         :ref:`ref-classes-useradd` class.
8667
8668      If you use static ``uid`` and ``gid`` information, you must also
8669      specify the ``files/passwd`` and ``files/group`` files by setting the
8670      :term:`USERADD_UID_TABLES` and
8671      :term:`USERADD_GID_TABLES` variables.
8672      Additionally, you should also set the
8673      :term:`USERADD_ERROR_DYNAMIC` variable.
8674
8675   :term:`VOLATILE_LOG_DIR`
8676      Specifies the persistence of the target's ``/var/log`` directory,
8677      which is used to house postinstall target log files.
8678
8679      By default, :term:`VOLATILE_LOG_DIR` is set to "yes", which means the
8680      file is not persistent. You can override this setting by setting the
8681      variable to "no" to make the log directory persistent.
8682
8683   :term:`WARN_QA`
8684      Specifies the quality assurance checks whose failures are reported as
8685      warnings by the OpenEmbedded build system. You set this variable in
8686      your distribution configuration file. For a list of the checks you
8687      can control with this variable, see the
8688      ":ref:`insane.bbclass <ref-classes-insane>`" section.
8689
8690   :term:`WKS_FILE`
8691      Specifies the location of the Wic kickstart file that is used by the
8692      OpenEmbedded build system to create a partitioned image
8693      (image\ ``.wic``). For information on how to create a partitioned
8694      image, see the
8695      ":ref:`dev-manual/common-tasks:creating partitioned images using wic`"
8696      section in the Yocto Project Development Tasks Manual. For details on
8697      the kickstart file format, see the ":doc:`/ref-manual/kickstart`" Chapter.
8698
8699   :term:`WKS_FILE_DEPENDS`
8700      When placed in the recipe that builds your image, this variable lists
8701      build-time dependencies. The :term:`WKS_FILE_DEPENDS` variable is only
8702      applicable when Wic images are active (i.e. when
8703      :term:`IMAGE_FSTYPES` contains entries related
8704      to Wic). If your recipe does not create Wic images, the variable has
8705      no effect.
8706
8707      The :term:`WKS_FILE_DEPENDS` variable is similar to the
8708      :term:`DEPENDS` variable. When you use the variable in
8709      your recipe that builds the Wic image, dependencies you list in the
8710      :term:`WKS_FILE_DEPENDS` variable are added to the :term:`DEPENDS` variable.
8711
8712      With the :term:`WKS_FILE_DEPENDS` variable, you have the possibility to
8713      specify a list of additional dependencies (e.g. native tools,
8714      bootloaders, and so forth), that are required to build Wic images.
8715      Following is an example::
8716
8717         WKS_FILE_DEPENDS = "some-native-tool"
8718
8719      In the
8720      previous example, some-native-tool would be replaced with an actual
8721      native tool on which the build would depend.
8722
8723   :term:`WORKDIR`
8724      The pathname of the work directory in which the OpenEmbedded build
8725      system builds a recipe. This directory is located within the
8726      :term:`TMPDIR` directory structure and is specific to
8727      the recipe being built and the system for which it is being built.
8728
8729      The :term:`WORKDIR` directory is defined as follows::
8730
8731         ${TMPDIR}/work/${MULTIMACH_TARGET_SYS}/${PN}/${EXTENDPE}${PV}-${PR}
8732
8733      The actual directory depends on several things:
8734
8735      -  :term:`TMPDIR`: The top-level build output directory
8736      -  :term:`MULTIMACH_TARGET_SYS`: The target system identifier
8737      -  :term:`PN`: The recipe name
8738      -  :term:`EXTENDPE`: The epoch - (if :term:`PE` is not specified, which
8739         is usually the case for most recipes, then `EXTENDPE` is blank)
8740      -  :term:`PV`: The recipe version
8741      -  :term:`PR`: The recipe revision
8742
8743      As an example, assume a Source Directory top-level folder name
8744      ``poky``, a default Build Directory at ``poky/build``, and a
8745      ``qemux86-poky-linux`` machine target system. Furthermore, suppose
8746      your recipe is named ``foo_1.3.0-r0.bb``. In this case, the work
8747      directory the build system uses to build the package would be as
8748      follows::
8749
8750         poky/build/tmp/work/qemux86-poky-linux/foo/1.3.0-r0
8751
8752   :term:`XSERVER`
8753      Specifies the packages that should be installed to provide an X
8754      server and drivers for the current machine, assuming your image
8755      directly includes ``packagegroup-core-x11-xserver`` or, perhaps
8756      indirectly, includes "x11-base" in
8757      :term:`IMAGE_FEATURES`.
8758
8759      The default value of :term:`XSERVER`, if not specified in the machine
8760      configuration, is "xserver-xorg xf86-video-fbdev xf86-input-evdev".
8761
8762