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<!DOCTYPE chapter PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"
[<!ENTITY % poky SYSTEM "../poky.ent"> %poky; ] >
<!-- Dummy chapter -->
<chapter id='ref-variables-glos'>
<title>Variables Glossary</title>
<para>
This chapter lists common variables used by BitBake and gives an overview
of their function and contents.
</para>
<note>
Following are some points regarding the variables listed in this glossary:
<itemizedlist>
<listitem><para>The variables listed in this glossary
are specific to BitBake.
Consequently, the descriptions are limited to that context.
</para></listitem>
<listitem><para>Also, variables exist in other systems that use BitBake
(e.g. The Yocto Project and OpenEmbedded) that have names identical
to those found in this glossary.
For such cases, the variables in those systems extend the
functionality of the variable as it is described here in
this glossary.
</para></listitem>
<listitem><para>Finally, there are variables mentioned in this
glossary that do not appear in the BitBake glossary.
These other variables are variables used in systems that use
BitBake.
</para></listitem>
</itemizedlist>
</note>
<glossary id='ref-variables-glossary'>
<para>
<link linkend='var-ASSUME_PROVIDED'>A</link>
<link linkend='var-B'>B</link>
<link linkend='var-CACHE'>C</link>
<link linkend='var-DEFAULT_PREFERENCE'>D</link>
<link linkend='var-EXCLUDE_FROM_WORLD'>E</link>
<link linkend='var-FAKEROOT'>F</link>
<link linkend='var-GITDIR'>G</link>
<link linkend='var-HGDIR'>H</link>
<!-- <link linkend='var-ICECC_DISABLED'>I</link> -->
<!-- <link linkend='var-glossary-j'>J</link> -->
<!-- <link linkend='var-KARCH'>K</link> -->
<link linkend='var-LAYERDEPENDS'>L</link>
<link linkend='var-MIRRORS'>M</link>
<!-- <link linkend='var-glossary-n'>N</link> -->
<link linkend='var-OVERRIDES'>O</link>
<link linkend='var-P4DIR'>P</link>
<!-- <link linkend='var-QMAKE_PROFILES'>Q</link> -->
<link linkend='var-RDEPENDS'>R</link>
<link linkend='var-SECTION'>S</link>
<link linkend='var-T'>T</link>
<!-- <link linkend='var-UBOOT_CONFIG'>U</link> -->
<!-- <link linkend='var-glossary-v'>V</link> -->
<!-- <link linkend='var-WARN_QA'>W</link> -->
<!-- <link linkend='var-glossary-x'>X</link> -->
<!-- <link linkend='var-glossary-y'>Y</link> -->
<!-- <link linkend='var-glossary-z'>Z</link>-->
</para>
<glossdiv id='var-glossary-a'><title>A</title>
<glossentry id='var-ASSUME_PROVIDED'><glossterm>ASSUME_PROVIDED</glossterm>
<glossdef>
<para>
Lists recipe names
(<link linkend='var-PN'><filename>PN</filename></link>
values) BitBake does not attempt to build.
Instead, BitBake assumes these recipes have already been
built.
</para>
<para>
In OpenEmbedded Core, <filename>ASSUME_PROVIDED</filename>
mostly specifies native tools that should not be built.
An example is <filename>git-native</filename>, which
when specified allows for the Git binary from the host to
be used rather than building
<filename>git-native</filename>.
</para>
</glossdef>
</glossentry>
</glossdiv>
<glossdiv id='var-glossary-b'><title>B</title>
<glossentry id='var-B'><glossterm>B</glossterm>
<glossdef>
<para>
The directory in which BitBake executes functions
during a recipe's build process.
</para>
</glossdef>
</glossentry>
<glossentry id='var-BB_ALLOWED_NETWORKS'><glossterm>BB_ALLOWED_NETWORKS</glossterm>
<glossdef>
<para>
Specifies a space-delimited list of hosts that the fetcher
is allowed to use to obtain the required source code.
Following are considerations surrounding this variable:
<itemizedlist>
<listitem><para>
This host list is only used if
<link linkend='var-BB_NO_NETWORK'><filename>BB_NO_NETWORK</filename></link>
is either not set or set to "0".
</para></listitem>
<listitem><para>
Limited support for wildcard matching against the
beginning of host names exists.
For example, the following setting matches
<filename>git.gnu.org</filename>,
<filename>ftp.gnu.org</filename>, and
<filename>foo.git.gnu.org</filename>.
<literallayout class='monospaced'>
BB_ALLOWED_NETWORKS = "*.gnu.org"
</literallayout>
</para></listitem>
<listitem><para>
Mirrors not in the host list are skipped and
logged in debug.
</para></listitem>
<listitem><para>
Attempts to access networks not in the host list
cause a failure.
</para></listitem>
</itemizedlist>
Using <filename>BB_ALLOWED_NETWORKS</filename> in
conjunction with
<link linkend='var-PREMIRRORS'><filename>PREMIRRORS</filename></link>
is very useful.
Adding the host you want to use to
<filename>PREMIRRORS</filename> results in the source code
being fetched from an allowed location and avoids raising
an error when a host that is not allowed is in a
<link linkend='var-SRC_URI'><filename>SRC_URI</filename></link>
statement.
This is because the fetcher does not attempt to use the
host listed in <filename>SRC_URI</filename> after a
successful fetch from the
<filename>PREMIRRORS</filename> occurs.
</para>
</glossdef>
</glossentry>
<glossentry id='var-BB_CONSOLELOG'><glossterm>BB_CONSOLELOG</glossterm>
<glossdef>
<para>
Specifies the path to a log file into which BitBake's user
interface writes output during the build.
</para>
</glossdef>
</glossentry>
<glossentry id='var-BB_CURRENTTASK'><glossterm>BB_CURRENTTASK</glossterm>
<glossdef>
<para>
Contains the name of the currently running task.
The name does not include the
<filename>do_</filename> prefix.
</para>
</glossdef>
</glossentry>
<glossentry id='var-BB_DANGLINGAPPENDS_WARNONLY'><glossterm>BB_DANGLINGAPPENDS_WARNONLY</glossterm>
<glossdef>
<para>
Defines how BitBake handles situations where an append
file (<filename>.bbappend</filename>) has no
corresponding recipe file (<filename>.bb</filename>).
This condition often occurs when layers get out of sync
(e.g. <filename>oe-core</filename> bumps a
recipe version and the old recipe no longer exists and the
other layer has not been updated to the new version
of the recipe yet).
</para>
<para>
The default fatal behavior is safest because it is
the sane reaction given something is out of sync.
It is important to realize when your changes are no longer
being applied.
</para>
</glossdef>
</glossentry>
<glossentry id='var-BB_DEFAULT_TASK'><glossterm>BB_DEFAULT_TASK</glossterm>
<glossdef>
<para>
The default task to use when none is specified (e.g.
with the <filename>-c</filename> command line option).
The task name specified should not include the
<filename>do_</filename> prefix.
</para>
</glossdef>
</glossentry>
<glossentry id='var-BB_DISKMON_DIRS'><glossterm>BB_DISKMON_DIRS</glossterm>
<glossdef>
<para>
Monitors disk space and available inodes during the build
and allows you to control the build based on these
parameters.
</para>
<para>
Disk space monitoring is disabled by default.
When setting this variable, use the following form:
<literallayout class='monospaced'>
BB_DISKMON_DIRS = "&lt;action&gt;,&lt;dir&gt;,&lt;threshold&gt; [...]"
where:
&lt;action&gt; is:
ABORT: Immediately abort the build when
a threshold is broken.
STOPTASKS: Stop the build after the currently
executing tasks have finished when
a threshold is broken.
WARN: Issue a warning but continue the
build when a threshold is broken.
Subsequent warnings are issued as
defined by the
<link linkend='var-BB_DISKMON_WARNINTERVAL'>BB_DISKMON_WARNINTERVAL</link> variable,
which must be defined.
&lt;dir&gt; is:
Any directory you choose. You can specify one or
more directories to monitor by separating the
groupings with a space. If two directories are
on the same device, only the first directory
is monitored.
&lt;threshold&gt; is:
Either the minimum available disk space,
the minimum number of free inodes, or
both. You must specify at least one. To
omit one or the other, simply omit the value.
Specify the threshold using G, M, K for Gbytes,
Mbytes, and Kbytes, respectively. If you do
not specify G, M, or K, Kbytes is assumed by
default. Do not use GB, MB, or KB.
</literallayout>
</para>
<para>
Here are some examples:
<literallayout class='monospaced'>
BB_DISKMON_DIRS = "ABORT,${TMPDIR},1G,100K WARN,${SSTATE_DIR},1G,100K"
BB_DISKMON_DIRS = "STOPTASKS,${TMPDIR},1G"
BB_DISKMON_DIRS = "ABORT,${TMPDIR},,100K"
</literallayout>
The first example works only if you also set
the <link linkend='var-BB_DISKMON_WARNINTERVAL'><filename>BB_DISKMON_WARNINTERVAL</filename></link> variable.
This example causes the build system to immediately
abort when either the disk space in <filename>${TMPDIR}</filename> drops
below 1 Gbyte or the available free inodes drops below
100 Kbytes.
Because two directories are provided with the variable, the
build system also issues a
warning when the disk space in the
<filename>${SSTATE_DIR}</filename> directory drops
below 1 Gbyte or the number of free inodes drops
below 100 Kbytes.
Subsequent warnings are issued during intervals as
defined by the <filename>BB_DISKMON_WARNINTERVAL</filename>
variable.
</para>
<para>
The second example stops the build after all currently
executing tasks complete when the minimum disk space
in the <filename>${TMPDIR}</filename>
directory drops below 1 Gbyte.
No disk monitoring occurs for the free inodes in this case.
</para>
<para>
The final example immediately aborts the build when the
number of free inodes in the <filename>${TMPDIR}</filename> directory
drops below 100 Kbytes.
No disk space monitoring for the directory itself occurs
in this case.
</para>
</glossdef>
</glossentry>
<glossentry id='var-BB_DISKMON_WARNINTERVAL'><glossterm>BB_DISKMON_WARNINTERVAL</glossterm>
<glossdef>
<para>
Defines the disk space and free inode warning intervals.
</para>
<para>
If you are going to use the
<filename>BB_DISKMON_WARNINTERVAL</filename> variable, you must
also use the
<link linkend='var-BB_DISKMON_DIRS'><filename>BB_DISKMON_DIRS</filename></link> variable
and define its action as "WARN".
During the build, subsequent warnings are issued each time
disk space or number of free inodes further reduces by
the respective interval.
</para>
<para>
If you do not provide a <filename>BB_DISKMON_WARNINTERVAL</filename>
variable and you do use <filename>BB_DISKMON_DIRS</filename> with
the "WARN" action, the disk monitoring interval defaults to
the following:
<literallayout class='monospaced'>
BB_DISKMON_WARNINTERVAL = "50M,5K"
</literallayout>
</para>
<para>
When specifying the variable in your configuration file,
use the following form:
<literallayout class='monospaced'>
BB_DISKMON_WARNINTERVAL = "&lt;disk_space_interval&gt;,&lt;disk_inode_interval&gt;"
where:
&lt;disk_space_interval&gt; is:
An interval of memory expressed in either
G, M, or K for Gbytes, Mbytes, or Kbytes,
respectively. You cannot use GB, MB, or KB.
&lt;disk_inode_interval&gt; is:
An interval of free inodes expressed in either
G, M, or K for Gbytes, Mbytes, or Kbytes,
respectively. You cannot use GB, MB, or KB.
</literallayout>
</para>
<para>
Here is an example:
<literallayout class='monospaced'>
BB_DISKMON_DIRS = "WARN,${SSTATE_DIR},1G,100K"
BB_DISKMON_WARNINTERVAL = "50M,5K"
</literallayout>
These variables cause BitBake to
issue subsequent warnings each time the available
disk space further reduces by 50 Mbytes or the number
of free inodes further reduces by 5 Kbytes in the
<filename>${SSTATE_DIR}</filename> directory.
Subsequent warnings based on the interval occur each time
a respective interval is reached beyond the initial warning
(i.e. 1 Gbytes and 100 Kbytes).
</para>
</glossdef>
</glossentry>
<glossentry id='var-BB_ENV_WHITELIST'><glossterm>BB_ENV_WHITELIST</glossterm>
<glossdef>
<para>
Specifies the internal whitelist of variables to allow
through from the external environment into BitBake's
datastore.
If the value of this variable is not specified
(which is the default), the following list is used:
<link linkend='var-BBPATH'><filename>BBPATH</filename></link>,
<link linkend='var-BB_PRESERVE_ENV'><filename>BB_PRESERVE_ENV</filename></link>,
<link linkend='var-BB_ENV_WHITELIST'><filename>BB_ENV_WHITELIST</filename></link>,
and
<link linkend='var-BB_ENV_EXTRAWHITE'><filename>BB_ENV_EXTRAWHITE</filename></link>.
<note>
You must set this variable in the external environment
in order for it to work.
</note>
</para>
</glossdef>
</glossentry>
<glossentry id='var-BB_ENV_EXTRAWHITE'><glossterm>BB_ENV_EXTRAWHITE</glossterm>
<glossdef>
<para>
Specifies an additional set of variables to allow through
(whitelist) from the external environment into BitBake's
datastore.
This list of variables are on top of the internal list
set in
<link linkend='var-BB_ENV_WHITELIST'><filename>BB_ENV_WHITELIST</filename></link>.
<note>
You must set this variable in the external
environment in order for it to work.
</note>
</para>
</glossdef>
</glossentry>
<glossentry id='var-BB_FETCH_PREMIRRORONLY'><glossterm>BB_FETCH_PREMIRRORONLY</glossterm>
<glossdef>
<para>
When set to "1", causes BitBake's fetcher module to only
search
<link linkend='var-PREMIRRORS'><filename>PREMIRRORS</filename></link>
for files.
BitBake will not search the main
<link linkend='var-SRC_URI'><filename>SRC_URI</filename></link>
or
<link linkend='var-MIRRORS'><filename>MIRRORS</filename></link>.
</para>
</glossdef>
</glossentry>
<glossentry id='var-BB_FILENAME'><glossterm>BB_FILENAME</glossterm>
<glossdef>
<para>
Contains the filename of the recipe that owns the currently
running task.
For example, if the <filename>do_fetch</filename> task that
resides in the <filename>my-recipe.bb</filename> is
executing, the <filename>BB_FILENAME</filename> variable
contains "/foo/path/my-recipe.bb".
</para>
</glossdef>
</glossentry>
<glossentry id='var-BB_GENERATE_MIRROR_TARBALLS'><glossterm>BB_GENERATE_MIRROR_TARBALLS</glossterm>
<glossdef>
<para>
Causes tarballs of the Git repositories, including the
Git metadata, to be placed in the
<link linkend='var-DL_DIR'><filename>DL_DIR</filename></link>
directory.
Anyone wishing to create a source mirror would want to
enable this variable.
</para>
<para>
For performance reasons, creating and placing tarballs of
the Git repositories is not the default action by BitBake.
<literallayout class='monospaced'>
BB_GENERATE_MIRROR_TARBALLS = "1"
</literallayout>
</para>
</glossdef>
</glossentry>
<glossentry id='var-BB_HASHCONFIG_WHITELIST'><glossterm>BB_HASHCONFIG_WHITELIST</glossterm>
<glossdef>
<para>
Lists variables that are excluded from base configuration
checksum, which is used to determine if the cache can
be reused.
</para>
<para>
One of the ways BitBake determines whether to re-parse the
main metadata is through checksums of the variables in the
datastore of the base configuration data.
There are variables that you typically want to exclude when
checking whether or not to re-parse and thus rebuild the
cache.
As an example, you would usually exclude
<filename>TIME</filename> and <filename>DATE</filename>
because these variables are always changing.
If you did not exclude them, BitBake would never reuse the
cache.
</para>
</glossdef>
</glossentry>
<glossentry id='var-BB_HASHBASE_WHITELIST'><glossterm>BB_HASHBASE_WHITELIST</glossterm>
<glossdef>
<para>
Lists variables that are excluded from checksum and
dependency data.
Variables that are excluded can therefore change without
affecting the checksum mechanism.
A common example would be the variable for the path of
the build.
BitBake's output should not (and usually does not) depend
on the directory in which it was built.
</para>
</glossdef>
</glossentry>
<glossentry id='var-BB_HASHCHECK_FUNCTION'><glossterm>BB_HASHCHECK_FUNCTION</glossterm>
<glossdef>
<para>
Specifies the name of the function to call during the
"setscene" part of the task's execution in order to
validate the list of task hashes.
The function returns the list of setscene tasks that should
be executed.
</para>
<para>
At this point in the execution of the code, the objective
is to quickly verify if a given setscene function is likely
to work or not.
It's easier to check the list of setscene functions in
one pass than to call many individual tasks.
The returned list need not be completely accurate.
A given setscene task can still later fail.
However, the more accurate the data returned, the more
efficient the build will be.
</para>
</glossdef>
</glossentry>
<glossentry id='var-BB_INVALIDCONF'><glossterm>BB_INVALIDCONF</glossterm>
<glossdef>
<para>
Used in combination with the
<filename>ConfigParsed</filename> event to trigger
re-parsing the base metadata (i.e. all the
recipes).
The <filename>ConfigParsed</filename> event can set the
variable to trigger the re-parse.
You must be careful to avoid recursive loops with this
functionality.
</para>
</glossdef>
</glossentry>
<glossentry id='var-BB_LOGFMT'><glossterm>BB_LOGFMT</glossterm>
<glossdef>
<para>
Specifies the name of the log files saved into
<filename>${</filename><link linkend='var-T'><filename>T</filename></link><filename>}</filename>.
By default, the <filename>BB_LOGFMT</filename> variable
is undefined and the log file names get created using the
following form:
<literallayout class='monospaced'>
log.{task}.{pid}
</literallayout>
If you want to force log files to take a specific name,
you can set this variable in a configuration file.
</para>
</glossdef>
</glossentry>
<glossentry id='var-BB_NICE_LEVEL'><glossterm>BB_NICE_LEVEL</glossterm>
<glossdef>
<para>
Allows BitBake to run at a specific priority
(i.e. nice level).
System permissions usually mean that BitBake can reduce its
priority but not raise it again.
See
<link linkend='var-BB_TASK_NICE_LEVEL'><filename>BB_TASK_NICE_LEVEL</filename></link>
for additional information.
</para>
</glossdef>
</glossentry>
<glossentry id='var-BB_NO_NETWORK'><glossterm>BB_NO_NETWORK</glossterm>
<glossdef>
<para>
Disables network access in the BitBake fetcher modules.
With this access disabled, any command that attempts to
access the network becomes an error.
</para>
<para>
Disabling network access is useful for testing source
mirrors, running builds when not connected to the Internet,
and when operating in certain kinds of firewall
environments.
</para>
</glossdef>
</glossentry>
<glossentry id='var-BB_NUMBER_THREADS'><glossterm>BB_NUMBER_THREADS</glossterm>
<glossdef>
<para>
The maximum number of tasks BitBake should run in parallel
at any one time.
If your host development system supports multiple cores,
a good rule of thumb is to set this variable to twice the
number of cores.
</para>
</glossdef>
</glossentry>
<glossentry id='var-BB_NUMBER_PARSE_THREADS'><glossterm>BB_NUMBER_PARSE_THREADS</glossterm>
<glossdef>
<para>
Sets the number of threads BitBake uses when parsing.
By default, the number of threads is equal to the number
of cores on the system.
</para>
</glossdef>
</glossentry>
<glossentry id='var-BB_ORIGENV'><glossterm>BB_ORIGENV</glossterm>
<glossdef>
<para>
Contains a copy of the original external environment in
which BitBake was run.
The copy is taken before any whitelisted variable values
are filtered into BitBake's datastore.
<note>
The contents of this variable is a datastore object
that can be queried using the normal datastore
operations.
</note>
</para>
</glossdef>
</glossentry>
<glossentry id='var-BB_PRESERVE_ENV'><glossterm>BB_PRESERVE_ENV</glossterm>
<glossdef>
<para>
Disables whitelisting and instead allows all variables
through from the external environment into BitBake's
datastore.
<note>
You must set this variable in the external
environment in order for it to work.
</note>
</para>
</glossdef>
</glossentry>
<glossentry id='var-BB_RUNFMT'><glossterm>BB_RUNFMT</glossterm>
<glossdef>
<para>
Specifies the name of the executable script files
(i.e. run files) saved into
<filename>${</filename><link linkend='var-T'><filename>T</filename></link><filename>}</filename>.
By default, the <filename>BB_RUNFMT</filename> variable
is undefined and the run file names get created using the
following form:
<literallayout class='monospaced'>
run.{task}.{pid}
</literallayout>
If you want to force run files to take a specific name,
you can set this variable in a configuration file.
</para>
</glossdef>
</glossentry>
<glossentry id='var-BB_RUNTASK'><glossterm>BB_RUNTASK</glossterm>
<glossdef>
<para>
Contains the name of the currently executing task.
The value does not include the "do_" prefix.
For example, if the currently executing task is
<filename>do_config</filename>, the value is
"config".
</para>
</glossdef>
</glossentry>
<glossentry id='var-BB_SCHEDULER'><glossterm>BB_SCHEDULER</glossterm>
<glossdef>
<para>
Selects the name of the scheduler to use for the
scheduling of BitBake tasks.
Three options exist:
<itemizedlist>
<listitem><para><emphasis>basic</emphasis> -
The basic framework from which everything derives.
Using this option causes tasks to be ordered
numerically as they are parsed.
</para></listitem>
<listitem><para><emphasis>speed</emphasis> -
Executes tasks first that have more tasks
depending on them.
The "speed" option is the default.
</para></listitem>
<listitem><para><emphasis>completion</emphasis> -
Causes the scheduler to try to complete a given
recipe once its build has started.
</para></listitem>
</itemizedlist>
</para>
</glossdef>
</glossentry>
<glossentry id='var-BB_SCHEDULERS'><glossterm>BB_SCHEDULERS</glossterm>
<glossdef>
<para>
Defines custom schedulers to import.
Custom schedulers need to be derived from the
<filename>RunQueueScheduler</filename> class.
</para>
<para>
For information how to select a scheduler, see the
<link linkend='var-BB_SCHEDULER'><filename>BB_SCHEDULER</filename></link>
variable.
</para>
</glossdef>
</glossentry>
<glossentry id='var-BB_SETSCENE_DEPVALID'><glossterm>BB_SETSCENE_DEPVALID</glossterm>
<glossdef>
<para>
Specifies a function BitBake calls that determines
whether BitBake requires a setscene dependency to be met.
</para>
<para>
When running a setscene task, BitBake needs to
know which dependencies of that setscene task also need
to be run.
Whether dependencies also need to be run is highly
dependent on the metadata.
The function specified by this variable returns a
"True" or "False" depending on whether the dependency needs
to be met.
</para>
</glossdef>
</glossentry>
<glossentry id='var-BB_SETSCENE_VERIFY_FUNCTION2'><glossterm>BB_SETSCENE_VERIFY_FUNCTION2</glossterm>
<glossdef>
<para>
Specifies a function to call that verifies the list of
planned task execution before the main task execution
happens.
The function is called once BitBake has a list of setscene
tasks that have run and either succeeded or failed.
</para>
<para>
The function allows for a task list check to see if they
make sense.
Even if BitBake was planning to skip a task, the
returned value of the function can force BitBake to run
the task, which is necessary under certain metadata
defined circumstances.
</para>
</glossdef>
</glossentry>
<glossentry id='var-BB_SIGNATURE_EXCLUDE_FLAGS'><glossterm>BB_SIGNATURE_EXCLUDE_FLAGS</glossterm>
<glossdef>
<para>
Lists variable flags (varflags)
that can be safely excluded from checksum
and dependency data for keys in the datastore.
When generating checksum or dependency data for keys in the
datastore, the flags set against that key are normally
included in the checksum.
</para>
<para>
For more information on varflags, see the
"<link linkend='variable-flags'>Variable Flags</link>"
section.
</para>
</glossdef>
</glossentry>
<glossentry id='var-BB_SIGNATURE_HANDLER'><glossterm>BB_SIGNATURE_HANDLER</glossterm>
<glossdef>
<para>
Defines the name of the signature handler BitBake uses.
The signature handler defines the way stamp files are
created and handled, if and how the signature is
incorporated into the stamps, and how the signature
itself is generated.
</para>
<para>
A new signature handler can be added by injecting a class
derived from the
<filename>SignatureGenerator</filename> class into the
global namespace.
</para>
</glossdef>
</glossentry>
<glossentry id='var-BB_SRCREV_POLICY'><glossterm>BB_SRCREV_POLICY</glossterm>
<glossdef>
<para>
Defines the behavior of the fetcher when it interacts with
source control systems and dynamic source revisions.
The <filename>BB_SRCREV_POLICY</filename> variable is
useful when working without a network.
</para>
<para>
The variable can be set using one of two policies:
<itemizedlist>
<listitem><para><emphasis>cache</emphasis> -
Retains the value the system obtained previously
rather than querying the source control system
each time.
</para></listitem>
<listitem><para><emphasis>clear</emphasis> -
Queries the source controls system every time.
With this policy, there is no cache.
The "clear" policy is the default.
</para></listitem>
</itemizedlist>
</para>
</glossdef>
</glossentry>
<glossentry id='var-BB_STAMP_POLICY'><glossterm>BB_STAMP_POLICY</glossterm>
<glossdef>
<para>
Defines the mode used for how timestamps of stamp files
are compared.
You can set the variable to one of the following modes:
<itemizedlist>
<listitem><para><emphasis>perfile</emphasis> -
Timestamp comparisons are only made
between timestamps of a specific recipe.
This is the default mode.
</para></listitem>
<listitem><para><emphasis>full</emphasis> -
Timestamp comparisons are made for all
dependencies.
</para></listitem>
<listitem><para><emphasis>whitelist</emphasis> -
Identical to "full" mode except timestamp
comparisons are made for recipes listed in the
<link linkend='var-BB_STAMP_WHITELIST'><filename>BB_STAMP_WHITELIST</filename></link>
variable.
</para></listitem>
</itemizedlist>
<note>
Stamp policies are largely obsolete with the
introduction of setscene tasks.
</note>
</para>
</glossdef>
</glossentry>
<glossentry id='var-BB_STAMP_WHITELIST'><glossterm>BB_STAMP_WHITELIST</glossterm>
<glossdef>
<para>
Lists files whose stamp file timestamps are compared when
the stamp policy mode is set to "whitelist".
For information on stamp policies, see the
<link linkend='var-BB_STAMP_POLICY'><filename>BB_STAMP_POLICY</filename></link>
variable.
</para>
</glossdef>
</glossentry>
<glossentry id='var-BB_STRICT_CHECKSUM'><glossterm>BB_STRICT_CHECKSUM</glossterm>
<glossdef>
<para>
Sets a more strict checksum mechanism for non-local URLs.
Setting this variable to a value causes BitBake
to report an error if it encounters a non-local URL
that does not have at least one checksum specified.
</para>
</glossdef>
</glossentry>
<glossentry id='var-BB_TASK_IONICE_LEVEL'><glossterm>BB_TASK_IONICE_LEVEL</glossterm>
<glossdef>
<para>
Allows adjustment of a task's Input/Output priority.
During Autobuilder testing, random failures can occur
for tasks due to I/O starvation.
These failures occur during various QEMU runtime timeouts.
You can use the <filename>BB_TASK_IONICE_LEVEL</filename>
variable to adjust the I/O priority of these tasks.
<note>
This variable works similarly to the
<link linkend='var-BB_TASK_NICE_LEVEL'><filename>BB_TASK_NICE_LEVEL</filename></link>
variable except with a task's I/O priorities.
</note>
</para>
<para>
Set the variable as follows:
<literallayout class='monospaced'>
BB_TASK_IONICE_LEVEL = "<replaceable>class</replaceable>.<replaceable>prio</replaceable>"
</literallayout>
For <replaceable>class</replaceable>, the default value is
"2", which is a best effort.
You can use "1" for realtime and "3" for idle.
If you want to use realtime, you must have superuser
privileges.
</para>
<para>
For <replaceable>prio</replaceable>, you can use any
value from "0", which is the highest priority, to "7",
which is the lowest.
The default value is "4".
You do not need any special privileges to use this range
of priority values.
<note>
In order for your I/O priority settings to take effect,
you need the Completely Fair Queuing (CFQ) Scheduler
selected for the backing block device.
To select the scheduler, use the following command form
where <replaceable>device</replaceable> is the device
(e.g. sda, sdb, and so forth):
<literallayout class='monospaced'>
$ sudo sh -c “echo cfq > /sys/block/<replaceable>device</replaceable>/queu/scheduler
</literallayout>
</note>
</para>
</glossdef>
</glossentry>
<glossentry id='var-BB_TASK_NICE_LEVEL'><glossterm>BB_TASK_NICE_LEVEL</glossterm>
<glossdef>
<para>
Allows specific tasks to change their priority
(i.e. nice level).
</para>
<para>
You can use this variable in combination with task
overrides to raise or lower priorities of specific tasks.
For example, on the
<ulink url='http://www.yoctoproject.org'>Yocto Project</ulink>
autobuilder, QEMU emulation in images is given a higher
priority as compared to build tasks to ensure that images
do not suffer timeouts on loaded systems.
</para>
</glossdef>
</glossentry>
<glossentry id='var-BB_TASKHASH'><glossterm>BB_TASKHASH</glossterm>
<glossdef>
<para>
Within an executing task, this variable holds the hash
of the task as returned by the currently enabled
signature generator.
</para>
</glossdef>
</glossentry>
<glossentry id='var-BB_VERBOSE_LOGS'><glossterm>BB_VERBOSE_LOGS</glossterm>
<glossdef>
<para>
Controls how verbose BitBake is during builds.
If set, shell scripts echo commands and shell script output
appears on standard out (stdout).
</para>
</glossdef>
</glossentry>
<glossentry id='var-BB_WORKERCONTEXT'><glossterm>BB_WORKERCONTEXT</glossterm>
<glossdef>
<para>
Specifies if the current context is executing a task.
BitBake sets this variable to "1" when a task is
being executed.
The value is not set when the task is in server context
during parsing or event handling.
</para>
</glossdef>
</glossentry>
<glossentry id='var-BBCLASSEXTEND'><glossterm>BBCLASSEXTEND</glossterm>
<glossdef>
<para>
Allows you to extend a recipe so that it builds variants
of the software.
Some examples of these variants for recipes from the
OpenEmbedded Core metadata are "natives" such as
<filename>quilt-native</filename>, which is a copy of
Quilt built to run on the build system; "crosses" such
as <filename>gcc-cross</filename>, which is a compiler
built to run on the build machine but produces binaries
that run on the target <filename>MACHINE</filename>;
"nativesdk", which targets the SDK machine instead of
<filename>MACHINE</filename>; and "mulitlibs" in the form
"<filename>multilib:</filename><replaceable>multilib_name</replaceable>".
</para>
<para>
To build a different variant of the recipe with a minimal
amount of code, it usually is as simple as adding the
variable to your recipe.
Here are two examples.
The "native" variants are from the OpenEmbedded Core
metadata:
<literallayout class='monospaced'>
BBCLASSEXTEND =+ "native nativesdk"
BBCLASSEXTEND =+ "multilib:<replaceable>multilib_name</replaceable>"
</literallayout>
<note>
<para>
Internally, the <filename>BBCLASSEXTEND</filename>
mechanism generates recipe variants by rewriting
variable values and applying overrides such as
<filename>_class-native</filename>.
For example, to generate a native version of a recipe,
a
<link linkend='var-DEPENDS'><filename>DEPENDS</filename></link>
on "foo" is rewritten to a <filename>DEPENDS</filename>
on "foo-native".
</para>
<para>
Even when using <filename>BBCLASSEXTEND</filename>, the
recipe is only parsed once.
Parsing once adds some limitations.
For example, it is not possible to
include a different file depending on the variant,
since <filename>include</filename> statements are
processed when the recipe is parsed.
</para>
</note>
</para>
</glossdef>
</glossentry>
<glossentry id='var-BBDEBUG'><glossterm>BBDEBUG</glossterm>
<glossdef>
<para>
Sets the BitBake debug output level to a specific value
as incremented by the <filename>-D</filename> command line
option.
<note>
You must set this variable in the external environment
in order for it to work.
</note>
</para>
</glossdef>
</glossentry>
<glossentry id='var-BBFILE_COLLECTIONS'><glossterm>BBFILE_COLLECTIONS</glossterm>
<glossdef>
<para>Lists the names of configured layers.
These names are used to find the other <filename>BBFILE_*</filename>
variables.
Typically, each layer appends its name to this variable in its
<filename>conf/layer.conf</filename> file.
</para>
</glossdef>
</glossentry>
<glossentry id='var-BBFILE_PATTERN'><glossterm>BBFILE_PATTERN</glossterm>
<glossdef>
<para>Variable that expands to match files from
<link linkend='var-BBFILES'><filename>BBFILES</filename></link>
in a particular layer.
This variable is used in the <filename>conf/layer.conf</filename> file and must
be suffixed with the name of the specific layer (e.g.
<filename>BBFILE_PATTERN_emenlow</filename>).</para>
</glossdef>
</glossentry>
<glossentry id='var-BBFILE_PRIORITY'><glossterm>BBFILE_PRIORITY</glossterm>
<glossdef>
<para>Assigns the priority for recipe files in each layer.</para>
<para>This variable is useful in situations where the same recipe appears in
more than one layer.
Setting this variable allows you to prioritize a
layer against other layers that contain the same recipe - effectively
letting you control the precedence for the multiple layers.
The precedence established through this variable stands regardless of a
recipe's version
(<link linkend='var-PV'><filename>PV</filename></link> variable).
For example, a layer that has a recipe with a higher <filename>PV</filename> value but for
which the <filename>BBFILE_PRIORITY</filename> is set to have a lower precedence still has a
lower precedence.</para>
<para>A larger value for the <filename>BBFILE_PRIORITY</filename> variable results in a higher
precedence.
For example, the value 6 has a higher precedence than the value 5.
If not specified, the <filename>BBFILE_PRIORITY</filename> variable is set based on layer
dependencies (see the
<filename><link linkend='var-LAYERDEPENDS'>LAYERDEPENDS</link></filename> variable for
more information.
The default priority, if unspecified
for a layer with no dependencies, is the lowest defined priority + 1
(or 1 if no priorities are defined).</para>
<tip>
You can use the command <filename>bitbake-layers show-layers</filename> to list
all configured layers along with their priorities.
</tip>
</glossdef>
</glossentry>
<glossentry id='var-BBFILES'><glossterm>BBFILES</glossterm>
<glossdef>
<para>List of recipe files BitBake uses to build software.</para>
</glossdef>
</glossentry>
<glossentry id='var-BBINCLUDED'><glossterm>BBINCLUDED</glossterm>
<glossdef>
<para>
Contains a space-separated list of all of all files that
BitBake's parser included during parsing of the current
file.
</para>
</glossdef>
</glossentry>
<glossentry id='var-BBINCLUDELOGS'><glossterm>BBINCLUDELOGS</glossterm>
<glossdef>
<para>
If set to a value, enables printing the task log when
reporting a failed task.
</para>
</glossdef>
</glossentry>
<glossentry id='var-BBINCLUDELOGS_LINES'><glossterm>BBINCLUDELOGS_LINES</glossterm>
<glossdef>
<para>
If
<link linkend='var-BBINCLUDELOGS'><filename>BBINCLUDELOGS</filename></link>
is set, specifies the maximum number of lines from the
task log file to print when reporting a failed task.
If you do not set <filename>BBINCLUDELOGS_LINES</filename>,
the entire log is printed.
</para>
</glossdef>
</glossentry>
<glossentry id='var-BBLAYERS'><glossterm>BBLAYERS</glossterm>
<glossdef>
<para>Lists the layers to enable during the build.
This variable is defined in the <filename>bblayers.conf</filename> configuration
file in the build directory.
Here is an example:
<literallayout class='monospaced'>
BBLAYERS = " \
/home/scottrif/poky/meta \
/home/scottrif/poky/meta-yocto \
/home/scottrif/poky/meta-yocto-bsp \
/home/scottrif/poky/meta-mykernel \
"
</literallayout>
This example enables four layers, one of which is a custom, user-defined layer
named <filename>meta-mykernel</filename>.
</para>
</glossdef>
</glossentry>
<glossentry id='var-BBLAYERS_FETCH_DIR'><glossterm>BBLAYERS_FETCH_DIR</glossterm>
<glossdef>
<para>
Sets the base location where layers are stored.
This setting is used in conjunction with
<filename>bitbake-layers layerindex-fetch</filename> and
tells <filename>bitbake-layers</filename> where to place
the fetched layers.
</para>
</glossdef>
</glossentry>
<glossentry id='var-BBMASK'><glossterm>BBMASK</glossterm>
<glossdef>
<para>
Prevents BitBake from processing recipes and recipe
append files.
</para>
<para>
You can use the <filename>BBMASK</filename> variable
to "hide" these <filename>.bb</filename> and
<filename>.bbappend</filename> files.
BitBake ignores any recipe or recipe append files that
match any of the expressions.
It is as if BitBake does not see them at all.
Consequently, matching files are not parsed or otherwise
used by BitBake.</para>
<para>
The values you provide are passed to Python's regular
expression compiler.
The expressions are compared against the full paths to
the files.
For complete syntax information, see Python's
documentation at
<ulink url='http://docs.python.org/release/2.3/lib/re-syntax.html'></ulink>.
</para>
<para>
The following example uses a complete regular expression
to tell BitBake to ignore all recipe and recipe append
files in the <filename>meta-ti/recipes-misc/</filename>
directory:
<literallayout class='monospaced'>
BBMASK = "meta-ti/recipes-misc/"
</literallayout>
If you want to mask out multiple directories or recipes,
you can specify multiple regular expression fragments.
This next example masks out multiple directories and
individual recipes:
<literallayout class='monospaced'>
BBMASK += "/meta-ti/recipes-misc/ meta-ti/recipes-ti/packagegroup/"
BBMASK += "/meta-oe/recipes-support/"
BBMASK += "/meta-foo/.*/openldap"
BBMASK += "opencv.*\.bbappend"
BBMASK += "lzma"
</literallayout>
<note>
When specifying a directory name, use the trailing
slash character to ensure you match just that directory
name.
</note>
</para>
</glossdef>
</glossentry>
<glossentry id='var-BBPATH'><glossterm>BBPATH</glossterm>
<glossdef>
<para>
Used by BitBake to locate class
(<filename>.bbclass</filename>) and configuration
(<filename>.conf</filename>) files.
This variable is analogous to the
<filename>PATH</filename> variable.
</para>
<para>
If you run BitBake from a directory outside of the
build directory,
you must be sure to set
<filename>BBPATH</filename> to point to the
build directory.
Set the variable as you would any environment variable
and then run BitBake:
<literallayout class='monospaced'>
$ BBPATH="<replaceable>build_directory</replaceable>"
$ export BBPATH
$ bitbake <replaceable>target</replaceable>
</literallayout>
</para>
</glossdef>
</glossentry>
<glossentry id='var-BBSERVER'><glossterm>BBSERVER</glossterm>
<glossdef>
<para>
Points to the server that runs memory-resident BitBake.
The variable is only used when you employ memory-resident
BitBake.
</para>
</glossdef>
</glossentry>
<glossentry id='var-BBTARGETS'><glossterm>BBTARGETS</glossterm>
<glossdef>
<para>
Allows you to use a configuration file to add to the list
of command-line target recipes you want to build.
</para>
</glossdef>
</glossentry>
<glossentry id='var-BBVERSIONS'><glossterm>BBVERSIONS</glossterm>
<glossdef>
<para>
Allows a single recipe to build multiple versions of a
project from a single recipe file.
You also able to specify conditional metadata
using the
<link linkend='var-OVERRIDES'><filename>OVERRIDES</filename></link>
mechanism for a single version or for an optionally named
range of versions.
</para>
<para>
For more information on <filename>BBVERSIONS</filename>,
see the
"<link linkend='variants-class-extension-mechanism'>Variants - Class Extension Mechanism</link>"
section.
</para>
</glossdef>
</glossentry>
<glossentry id='var-BITBAKE_UI'><glossterm>BITBAKE_UI</glossterm>
<glossdef>
<para>
Used to specify the UI module to use when running BitBake.
Using this variable is equivalent to using the
<filename>-u</filename> command-line option.
<note>
You must set this variable in the external environment
in order for it to work.
</note>
</para>
</glossdef>
</glossentry>
<glossentry id='var-BUILDNAME'><glossterm>BUILDNAME</glossterm>
<glossdef>
<para>
A name assigned to the build.
The name defaults to a datetime stamp of when the build was
started but can be defined by the metadata.
</para>
</glossdef>
</glossentry>
<glossentry id='var-BZRDIR'><glossterm>BZRDIR</glossterm>
<glossdef>
<para>
The directory in which files checked out of a Bazaar
system are stored.
</para>
</glossdef>
</glossentry>
</glossdiv>
<glossdiv id='var-glossary-c'><title>C</title>
<glossentry id='var-CACHE'><glossterm>CACHE</glossterm>
<glossdef>
<para>
Specifies the directory BitBake uses to store a cache
of the metadata so it does not need to be parsed every
time BitBake is started.
</para>
</glossdef>
</glossentry>
<glossentry id='var-CVSDIR'><glossterm>CVSDIR</glossterm>
<glossdef>
<para>
The directory in which files checked out under the
CVS system are stored.
</para>
</glossdef>
</glossentry>
</glossdiv>
<glossdiv id='var-glossary-d'><title>D</title>
<glossentry id='var-DEFAULT_PREFERENCE'><glossterm>DEFAULT_PREFERENCE</glossterm>
<glossdef>
<para>
Specifies a weak bias for recipe selection priority.
</para>
<para>
The most common usage of this is variable is to set
it to "-1" within a recipe for a development version of a
piece of software.
Using the variable in this way causes the stable version
of the recipe to build by default in the absence of
<filename><link linkend='var-PREFERRED_VERSION'>PREFERRED_VERSION</link></filename>
being used to build the development version.
</para>
<note>
The bias provided by <filename>DEFAULT_PREFERENCE</filename>
is weak and is overridden by
<filename><link linkend='var-BBFILE_PRIORITY'>BBFILE_PRIORITY</link></filename>
if that variable is different between two layers
that contain different versions of the same recipe.
</note>
</glossdef>
</glossentry>
<glossentry id='var-DEPENDS'><glossterm>DEPENDS</glossterm>
<glossdef>
<para>
Lists a recipe's build-time dependencies
(i.e. other recipe files).
</para>
<para>
Consider this simple example for two recipes named "a" and
"b" that produce similarly named packages.
In this example, the <filename>DEPENDS</filename>
statement appears in the "a" recipe:
<literallayout class='monospaced'>
DEPENDS = "b"
</literallayout>
Here, the dependency is such that the
<filename>do_configure</filename> task for recipe "a"
depends on the <filename>do_populate_sysroot</filename>
task of recipe "b".
This means anything that recipe "b" puts into sysroot
is available when recipe "a" is configuring itself.
</para>
<para>
For information on runtime dependencies, see the
<link linkend='var-RDEPENDS'><filename>RDEPENDS</filename></link>
variable.
</para>
</glossdef>
</glossentry>
<glossentry id='var-DESCRIPTION'><glossterm>DESCRIPTION</glossterm>
<glossdef>
<para>
A long description for the recipe.
</para>
</glossdef>
</glossentry>
<glossentry id='var-DL_DIR'><glossterm>DL_DIR</glossterm>
<glossdef>
<para>
The central download directory used by the build process to
store downloads.
By default, <filename>DL_DIR</filename> gets files
suitable for mirroring for everything except Git
repositories.
If you want tarballs of Git repositories, use the
<link linkend='var-BB_GENERATE_MIRROR_TARBALLS'><filename>BB_GENERATE_MIRROR_TARBALLS</filename></link>
variable.
</para>
</glossdef>
</glossentry>
</glossdiv>
<glossdiv id='var-glossary-e'><title>E</title>
<glossentry id='var-EXCLUDE_FROM_WORLD'><glossterm>EXCLUDE_FROM_WORLD</glossterm>
<glossdef>
<para>
Directs BitBake to exclude a recipe from world builds (i.e.
<filename>bitbake world</filename>).
During world builds, BitBake locates, parses and builds all
recipes found in every layer exposed in the
<filename>bblayers.conf</filename> configuration file.
</para>
<para>
To exclude a recipe from a world build using this variable,
set the variable to "1" in the recipe.
</para>
<note>
Recipes added to <filename>EXCLUDE_FROM_WORLD</filename>
may still be built during a world build in order to satisfy
dependencies of other recipes.
Adding a recipe to <filename>EXCLUDE_FROM_WORLD</filename>
only ensures that the recipe is not explicitly added
to the list of build targets in a world build.
</note>
</glossdef>
</glossentry>
</glossdiv>
<glossdiv id='var-glossary-f'><title>F</title>
<glossentry id='var-FAKEROOT'><glossterm>FAKEROOT</glossterm>
<glossdef>
<para>
Contains the command to use when running a shell script
in a fakeroot environment.
The <filename>FAKEROOT</filename> variable is obsolete
and has been replaced by the other
<filename>FAKEROOT*</filename> variables.
See these entries in the glossary for more information.
</para>
</glossdef>
</glossentry>
<glossentry id='var-FAKEROOTBASEENV'><glossterm>FAKEROOTBASEENV</glossterm>
<glossdef>
<para>
Lists environment variables to set when executing
the command defined by
<link linkend='var-FAKEROOTCMD'><filename>FAKEROOTCMD</filename></link>
that starts the bitbake-worker process
in the fakeroot environment.
</para>
</glossdef>
</glossentry>
<glossentry id='var-FAKEROOTCMD'><glossterm>FAKEROOTCMD</glossterm>
<glossdef>
<para>
Contains the command that starts the bitbake-worker
process in the fakeroot environment.
</para>
</glossdef>
</glossentry>
<glossentry id='var-FAKEROOTDIRS'><glossterm>FAKEROOTDIRS</glossterm>
<glossdef>
<para>
Lists directories to create before running a task in
the fakeroot environment.
</para>
</glossdef>
</glossentry>
<glossentry id='var-FAKEROOTENV'><glossterm>FAKEROOTENV</glossterm>
<glossdef>
<para>
Lists environment variables to set when running a task
in the fakeroot environment.
For additional information on environment variables and
the fakeroot environment, see the
<link linkend='var-FAKEROOTBASEENV'><filename>FAKEROOTBASEENV</filename></link>
variable.
</para>
</glossdef>
</glossentry>
<glossentry id='var-FAKEROOTNOENV'><glossterm>FAKEROOTNOENV</glossterm>
<glossdef>
<para>
Lists environment variables to set when running a task
that is not in the fakeroot environment.
For additional information on environment variables and
the fakeroot environment, see the
<link linkend='var-FAKEROOTENV'><filename>FAKEROOTENV</filename></link>
variable.
</para>
</glossdef>
</glossentry>
<glossentry id='var-FETCHCMD'><glossterm>FETCHCMD</glossterm>
<glossdef>
<para>
Defines the command the BitBake fetcher module
executes when running fetch operations.
You need to use an override suffix when you use the
variable (e.g. <filename>FETCHCMD_git</filename>
or <filename>FETCHCMD_svn</filename>).
</para>
</glossdef>
</glossentry>
<glossentry id='var-FILE'><glossterm>FILE</glossterm>
<glossdef>
<para>
Points at the current file.
BitBake sets this variable during the parsing process
to identify the file being parsed.
BitBake also sets this variable when a recipe is being
executed to identify the recipe file.
</para>
</glossdef>
</glossentry>
<glossentry id='var-FILESPATH'><glossterm>FILESPATH</glossterm>
<glossdef>
<para>
Specifies directories BitBake uses when searching for
patches and files.
The "local" fetcher module uses these directories when
handling <filename>file://</filename> URLs.
The variable behaves like a shell <filename>PATH</filename>
environment variable.
The value is a colon-separated list of directories that
are searched left-to-right in order.
</para>
</glossdef>
</glossentry>
</glossdiv>
<glossdiv id='var-glossary-g'><title>G</title>
<glossentry id='var-GITDIR'><glossterm>GITDIR</glossterm>
<glossdef>
<para>
The directory in which a local copy of a Git repository
is stored when it is cloned.
</para>
</glossdef>
</glossentry>
</glossdiv>
<glossdiv id='var-glossary-h'><title>H</title>
<glossentry id='var-HGDIR'><glossterm>HGDIR</glossterm>
<glossdef>
<para>
The directory in which files checked out of a Mercurial
system are stored.
</para>
</glossdef>
</glossentry>
<glossentry id='var-HOMEPAGE'><glossterm>HOMEPAGE</glossterm>
<glossdef>
<para>Website where more information about the software the recipe is building
can be found.</para>
</glossdef>
</glossentry>
</glossdiv>
<glossdiv id='var-glossary-i'><title>I</title>
<glossentry id='var-INHERIT'><glossterm>INHERIT</glossterm>
<glossdef>
<para>
Causes the named class or classes to be inherited globally.
Anonymous functions in the class or classes
are not executed for the
base configuration and in each individual recipe.
The OpenEmbedded build system ignores changes to
<filename>INHERIT</filename> in individual recipes.
</para>
<para>
For more information on <filename>INHERIT</filename>, see
the
"<link linkend="inherit-configuration-directive"><filename>INHERIT</filename> Configuration Directive</link>"
section.
</para>
</glossdef>
</glossentry>
</glossdiv>
<!--
<glossdiv id='var-glossary-j'><title>J</title>
</glossdiv>
<glossdiv id='var-glossary-k'><title>K</title>
</glossdiv>
-->
<glossdiv id='var-glossary-l'><title>L</title>
<glossentry id='var-LAYERDEPENDS'><glossterm>LAYERDEPENDS</glossterm>
<glossdef>
<para>Lists the layers, separated by spaces, upon which this recipe depends.
Optionally, you can specify a specific layer version for a dependency
by adding it to the end of the layer name with a colon, (e.g. "anotherlayer:3"
to be compared against
<link linkend='var-LAYERVERSION'><filename>LAYERVERSION</filename></link><filename>_anotherlayer</filename>
in this case).
BitBake produces an error if any dependency is missing or
the version numbers do not match exactly (if specified).</para>
<para>
You use this variable in the <filename>conf/layer.conf</filename> file.
You must also use the specific layer name as a suffix
to the variable (e.g. <filename>LAYERDEPENDS_mylayer</filename>).</para>
</glossdef>
</glossentry>
<glossentry id='var-LAYERDIR'><glossterm>LAYERDIR</glossterm>
<glossdef>
<para>When used inside the <filename>layer.conf</filename> configuration
file, this variable provides the path of the current layer.
This variable is not available outside of <filename>layer.conf</filename>
and references are expanded immediately when parsing of the file completes.</para>
</glossdef>
</glossentry>
<glossentry id='var-LAYERDIR_RE'><glossterm>LAYERDIR_RE</glossterm>
<glossdef>
<para>When used inside the <filename>layer.conf</filename> configuration
file, this variable provides the path of the current layer,
escaped for use in a regular expression
(<link linkend='var-BBFILE_PATTERN'><filename>BBFILE_PATTERN</filename></link>).
This variable is not available outside of <filename>layer.conf</filename>
and references are expanded immediately when parsing of the file completes.</para>
</glossdef>
</glossentry>
<glossentry id='var-LAYERVERSION'><glossterm>LAYERVERSION</glossterm>
<glossdef>
<para>Optionally specifies the version of a layer as a single number.
You can use this variable within
<link linkend='var-LAYERDEPENDS'><filename>LAYERDEPENDS</filename></link>
for another layer in order to depend on a specific version
of the layer.</para>
<para>
You use this variable in the <filename>conf/layer.conf</filename> file.
You must also use the specific layer name as a suffix
to the variable (e.g. <filename>LAYERDEPENDS_mylayer</filename>).</para>
</glossdef>
</glossentry>
<glossentry id='var-LICENSE'><glossterm>LICENSE</glossterm>
<glossdef>
<para>
The list of source licenses for the recipe.
</para>
</glossdef>
</glossentry>
</glossdiv>
<glossdiv id='var-glossary-m'><title>M</title>
<glossentry id='var-MIRRORS'><glossterm>MIRRORS</glossterm>
<glossdef>
<para>
Specifies additional paths from which BitBake gets source code.
When the build system searches for source code, it first
tries the local download directory.
If that location fails, the build system tries locations
defined by
<link linkend='var-PREMIRRORS'><filename>PREMIRRORS</filename></link>,
the upstream source, and then locations specified by
<filename>MIRRORS</filename> in that order.
</para>
</glossdef>
</glossentry>
<glossentry id='var-MULTI_PROVIDER_WHITELIST'><glossterm>MULTI_PROVIDER_WHITELIST</glossterm>
<glossdef>
<para>
Allows you to suppress BitBake warnings caused when
building two separate recipes that provide the same
output.
</para>
<para>
Bitbake normally issues a warning when building two
different recipes where each provides the same output.
This scenario is usually something the user does not
want.
However, cases do exist where it makes sense, particularly
in the <filename>virtual/*</filename> namespace.
You can use this variable to suppress BitBake's warnings.
</para>
<para>
To use the variable, list provider names (e.g.
recipe names, <filename>virtual/kernel</filename>,
and so forth).
</para>
</glossdef>
</glossentry>
</glossdiv>
<!--
<glossdiv id='var-glossary-n'><title>N</title>
</glossdiv>
-->
<glossdiv id='var-glossary-o'><title>O</title>
<glossentry id='var-OVERRIDES'><glossterm>OVERRIDES</glossterm>
<glossdef>
<para>
BitBake uses <filename>OVERRIDES</filename> to control
what variables are overridden after BitBake parses
recipes and configuration files.
</para>
<para>
Following is a simple example that uses an overrides
list based on machine architectures:
<literallayout class='monospaced'>
OVERRIDES = "arm:x86:mips:powerpc"
</literallayout>
You can find information on how to use
<filename>OVERRIDES</filename> in the
"<link linkend='conditional-syntax-overrides'>Conditional Syntax (Overrides)</link>"
section.
</para>
</glossdef>
</glossentry>
</glossdiv>
<glossdiv id='var-glossary-p'><title>P</title>
<glossentry id='var-P4DIR'><glossterm>P4DIR</glossterm>
<glossdef>
<para>
The directory in which a local copy of a Perforce depot
is stored when it is fetched.
</para>
</glossdef>
</glossentry>
<glossentry id='var-PACKAGES'><glossterm>PACKAGES</glossterm>
<glossdef>
<para>The list of packages the recipe creates.
</para>
</glossdef>
</glossentry>
<glossentry id='var-PACKAGES_DYNAMIC'><glossterm>PACKAGES_DYNAMIC</glossterm>
<glossdef>
<para>
A promise that your recipe satisfies runtime dependencies
for optional modules that are found in other recipes.
<filename>PACKAGES_DYNAMIC</filename>
does not actually satisfy the dependencies, it only states that
they should be satisfied.
For example, if a hard, runtime dependency
(<link linkend='var-RDEPENDS'><filename>RDEPENDS</filename></link>)
of another package is satisfied during the build
through the <filename>PACKAGES_DYNAMIC</filename>
variable, but a package with the module name is never actually
produced, then the other package will be broken.
</para>
</glossdef>
</glossentry>
<glossentry id='var-PE'><glossterm>PE</glossterm>
<glossdef>
<para>
The epoch of the recipe.
By default, this variable is unset.
The variable is used to make upgrades possible when the
versioning scheme changes in some backwards incompatible
way.
</para>
</glossdef>
</glossentry>
<glossentry id='var-PERSISTENT_DIR'><glossterm>PERSISTENT_DIR</glossterm>
<glossdef>
<para>
Specifies the directory BitBake uses to store data that
should be preserved between builds.
In particular, the data stored is the data that uses
BitBake's persistent data API and the data used by the
PR Server and PR Service.
</para>
</glossdef>
</glossentry>
<glossentry id='var-PF'><glossterm>PF</glossterm>
<glossdef>
<para>
Specifies the recipe or package name and includes all version and revision
numbers (i.e. <filename>eglibc-2.13-r20+svnr15508/</filename> and
<filename>bash-4.2-r1/</filename>).
</para>
</glossdef>
</glossentry>
<glossentry id='var-PN'><glossterm>PN</glossterm>
<glossdef>
<para>The recipe name.</para>
</glossdef>
</glossentry>
<glossentry id='var-PR'><glossterm>PR</glossterm>
<glossdef>
<para>The revision of the recipe.
</para>
</glossdef>
</glossentry>
<glossentry id='var-PREFERRED_PROVIDER'><glossterm>PREFERRED_PROVIDER</glossterm>
<glossdef>
<para>
Determines which recipe should be given preference when
multiple recipes provide the same item.
You should always suffix the variable with the name of the
provided item, and you should set it to the
<link linkend='var-PN'><filename>PN</filename></link>
of the recipe to which you want to give precedence.
Some examples:
<literallayout class='monospaced'>
PREFERRED_PROVIDER_virtual/kernel ?= "linux-yocto"
PREFERRED_PROVIDER_virtual/xserver = "xserver-xf86"
PREFERRED_PROVIDER_virtual/libgl ?= "mesa"
</literallayout>
</para>
</glossdef>
</glossentry>
<glossentry id='var-PREFERRED_PROVIDERS'><glossterm>PREFERRED_PROVIDERS</glossterm>
<glossdef>
<para>
Determines which recipe should be given preference for
cases where multiple recipes provide the same item.
Functionally,
<filename>PREFERRED_PROVIDERS</filename> is identical to
<link linkend='var-PREFERRED_PROVIDER'><filename>PREFERRED_PROVIDER</filename></link>.
However, the <filename>PREFERRED_PROVIDERS</filename>
variable lets you define preferences for multiple
situations using the following form:
<literallayout class='monospaced'>
PREFERRED_PROVIDERS = "xxx:yyy aaa:bbb ..."
</literallayout>
This form is a convenient replacement for the following:
<literallayout class='monospaced'>
PREFERRED_PROVIDER_xxx = "yyy"
PREFERRED_PROVIDER_aaa = "bbb"
</literallayout>
</para>
</glossdef>
</glossentry>
<glossentry id='var-PREFERRED_VERSION'><glossterm>PREFERRED_VERSION</glossterm>
<glossdef>
<para>
If there are multiple versions of recipes available, this
variable determines which recipe should be given preference.
You must always suffix the variable with the
<link linkend='var-PN'><filename>PN</filename></link>
you want to select, and you should set
<link linkend='var-PV'><filename>PV</filename></link>
accordingly for precedence.
You can use the "<filename>%</filename>" character as a
wildcard to match any number of characters, which can be
useful when specifying versions that contain long revision
numbers that could potentially change.
Here are two examples:
<literallayout class='monospaced'>
PREFERRED_VERSION_python = "2.7.3"
PREFERRED_VERSION_linux-yocto = "4.12%"
</literallayout>
</para>
</glossdef>
</glossentry>
<glossentry id='var-PREMIRRORS'><glossterm>PREMIRRORS</glossterm>
<glossdef>
<para>
Specifies additional paths from which BitBake gets source code.
When the build system searches for source code, it first
tries the local download directory.
If that location fails, the build system tries locations
defined by <filename>PREMIRRORS</filename>, the upstream
source, and then locations specified by
<link linkend='var-MIRRORS'><filename>MIRRORS</filename></link>
in that order.
</para>
<para>
Typically, you would add a specific server for the
build system to attempt before any others by adding
something like the following to your configuration:
<literallayout class='monospaced'>
PREMIRRORS_prepend = "\
git://.*/.* http://www.yoctoproject.org/sources/ \n \
ftp://.*/.* http://www.yoctoproject.org/sources/ \n \
http://.*/.* http://www.yoctoproject.org/sources/ \n \
https://.*/.* http://www.yoctoproject.org/sources/ \n"
</literallayout>
These changes cause the build system to intercept
Git, FTP, HTTP, and HTTPS requests and direct them to
the <filename>http://</filename> sources mirror.
You can use <filename>file://</filename> URLs to point
to local directories or network shares as well.
</para>
</glossdef>
</glossentry>
<glossentry id='var-PROVIDES'><glossterm>PROVIDES</glossterm>
<glossdef>
<para>
A list of aliases by which a particular recipe can be
known.
By default, a recipe's own
<filename><link linkend='var-PN'>PN</link></filename>
is implicitly already in its <filename>PROVIDES</filename>
list.
If a recipe uses <filename>PROVIDES</filename>, the
additional aliases are synonyms for the recipe and can
be useful satisfying dependencies of other recipes during
the build as specified by
<filename><link linkend='var-DEPENDS'>DEPENDS</link></filename>.
</para>
<para>
Consider the following example
<filename>PROVIDES</filename> statement from a recipe
file <filename>libav_0.8.11.bb</filename>:
<literallayout class='monospaced'>
PROVIDES += "libpostproc"
</literallayout>
The <filename>PROVIDES</filename> statement results in
the "libav" recipe also being known as "libpostproc".
</para>
<para>
In addition to providing recipes under alternate names,
the <filename>PROVIDES</filename> mechanism is also used
to implement virtual targets.
A virtual target is a name that corresponds to some
particular functionality (e.g. a Linux kernel).
Recipes that provide the functionality in question list the
virtual target in <filename>PROVIDES</filename>.
Recipes that depend on the functionality in question can
include the virtual target in
<link linkend='var-DEPENDS'><filename>DEPENDS</filename></link>
to leave the choice of provider open.
</para>
<para>
Conventionally, virtual targets have names on the form
"virtual/function" (e.g. "virtual/kernel").
The slash is simply part of the name and has no
syntactical significance.
</para>
</glossdef>
</glossentry>
<glossentry id='var-PRSERV_HOST'><glossterm>PRSERV_HOST</glossterm>
<glossdef>
<para>
The network based
<link linkend='var-PR'><filename>PR</filename></link>
service host and port.
</para>
<para>
Following is an example of how the <filename>PRSERV_HOST</filename> variable is
set:
<literallayout class='monospaced'>
PRSERV_HOST = "localhost:0"
</literallayout>
You must set the variable if you want to automatically
start a local PR service.
You can set <filename>PRSERV_HOST</filename> to other
values to use a remote PR service.
</para>
</glossdef>
</glossentry>
<glossentry id='var-PV'><glossterm>PV</glossterm>
<glossdef>
<para>The version of the recipe.
</para>
</glossdef>
</glossentry>
</glossdiv>
<!--
<glossdiv id='var-glossary-q'><title>Q</title>
</glossdiv>
-->
<glossdiv id='var-glossary-r'><title>R</title>
<glossentry id='var-RDEPENDS'><glossterm>RDEPENDS</glossterm>
<glossdef>
<para>
Lists a package's runtime dependencies (i.e. other packages)
that must be installed in order for the built package to run
correctly.
If a package in this list cannot be found during the build,
you will get a build error.
</para>
<para>
Because the <filename>RDEPENDS</filename> variable applies
to packages being built, you should always use the variable
in a form with an attached package name.
For example, suppose you are building a development package
that depends on the <filename>perl</filename> package.
In this case, you would use the following
<filename>RDEPENDS</filename> statement:
<literallayout class='monospaced'>
RDEPENDS_${PN}-dev += "perl"
</literallayout>
In the example, the development package depends on
the <filename>perl</filename> package.
Thus, the <filename>RDEPENDS</filename> variable has the
<filename>${PN}-dev</filename> package name as part of the
variable.
</para>
<para>
BitBake supports specifying versioned dependencies.
Although the syntax varies depending on the packaging
format, BitBake hides these differences from you.
Here is the general syntax to specify versions with
the <filename>RDEPENDS</filename> variable:
<literallayout class='monospaced'>
RDEPENDS_${PN} = "<replaceable>package</replaceable> (<replaceable>operator</replaceable> <replaceable>version</replaceable>)"
</literallayout>
For <filename>operator</filename>, you can specify the
following:
<literallayout class='monospaced'>
=
&lt;
&gt;
&lt;=
&gt;=
</literallayout>
For example, the following sets up a dependency on version
1.2 or greater of the package <filename>foo</filename>:
<literallayout class='monospaced'>
RDEPENDS_${PN} = "foo (>= 1.2)"
</literallayout>
</para>
<para>
For information on build-time dependencies, see the
<link linkend='var-DEPENDS'><filename>DEPENDS</filename></link>
variable.
</para>
</glossdef>
</glossentry>
<glossentry id='var-RPROVIDES'><glossterm>RPROVIDES</glossterm>
<glossdef>
<para>
A list of package name aliases that a package also provides.
These aliases are useful for satisfying runtime dependencies
of other packages both during the build and on the target
(as specified by
<filename><link linkend='var-RDEPENDS'>RDEPENDS</link></filename>).
</para>
<para>
As with all package-controlling variables, you must always
use the variable in conjunction with a package name override.
Here is an example:
<literallayout class='monospaced'>
RPROVIDES_${PN} = "widget-abi-2"
</literallayout>
</para>
</glossdef>
</glossentry>
<glossentry id='var-RRECOMMENDS'><glossterm>RRECOMMENDS</glossterm>
<glossdef>
<para>
A list of packages that extends the usability of a package
being built.
The package being built does not depend on this list of
packages in order to successfully build, but needs them for
the extended usability.
To specify runtime dependencies for packages, see the
<filename><link linkend='var-RDEPENDS'>RDEPENDS</link></filename>
variable.
</para>
<para>
BitBake supports specifying versioned recommends.
Although the syntax varies depending on the packaging
format, BitBake hides these differences from you.
Here is the general syntax to specify versions with
the <filename>RRECOMMENDS</filename> variable:
<literallayout class='monospaced'>
RRECOMMENDS_${PN} = "<replaceable>package</replaceable> (<replaceable>operator</replaceable> <replaceable>version</replaceable>)"
</literallayout>
For <filename>operator</filename>, you can specify the
following:
<literallayout class='monospaced'>
=
&lt;
&gt;
&lt;=
&gt;=
</literallayout>
For example, the following sets up a recommend on version
1.2 or greater of the package <filename>foo</filename>:
<literallayout class='monospaced'>
RRECOMMENDS_${PN} = "foo (>= 1.2)"
</literallayout>
</para>
</glossdef>
</glossentry>
</glossdiv>
<glossdiv id='var-glossary-s'><title>S</title>
<glossentry id='var-SECTION'><glossterm>SECTION</glossterm>
<glossdef>
<para>The section in which packages should be categorized.</para>
</glossdef>
</glossentry>
<glossentry id='var-SRC_URI'><glossterm>SRC_URI</glossterm>
<glossdef>
<para>
The list of source files - local or remote.
This variable tells BitBake which bits
to pull for the build and how to pull them.
For example, if the recipe or append file needs to
fetch a single tarball from the Internet, the recipe or
append file uses a <filename>SRC_URI</filename>
entry that specifies that tarball.
On the other hand, if the recipe or append file needs to
fetch a tarball and include a custom file, the recipe or
append file needs an <filename>SRC_URI</filename> variable
that specifies all those sources.</para>
<para>The following list explains the available URI protocols:
<itemizedlist>
<listitem><para><emphasis><filename>file://</filename> -</emphasis>
Fetches files, which are usually files shipped with
the metadata,
from the local machine.
The path is relative to the
<link linkend='var-FILESPATH'><filename>FILESPATH</filename></link>
variable.</para></listitem>
<listitem><para><emphasis><filename>bzr://</filename> -</emphasis> Fetches files from a
Bazaar revision control repository.</para></listitem>
<listitem><para><emphasis><filename>git://</filename> -</emphasis> Fetches files from a
Git revision control repository.</para></listitem>
<listitem><para><emphasis><filename>osc://</filename> -</emphasis> Fetches files from
an OSC (OpenSUSE Build service) revision control repository.</para></listitem>
<listitem><para><emphasis><filename>repo://</filename> -</emphasis> Fetches files from
a repo (Git) repository.</para></listitem>
<listitem><para><emphasis><filename>http://</filename> -</emphasis> Fetches files from
the Internet using HTTP.</para></listitem>
<listitem><para><emphasis><filename>https://</filename> -</emphasis> Fetches files
from the Internet using HTTPS.</para></listitem>
<listitem><para><emphasis><filename>ftp://</filename> -</emphasis> Fetches files
from the Internet using FTP.</para></listitem>
<listitem><para><emphasis><filename>cvs://</filename> -</emphasis> Fetches files from
a CVS revision control repository.</para></listitem>
<listitem><para><emphasis><filename>hg://</filename> -</emphasis> Fetches files from
a Mercurial (<filename>hg</filename>) revision control repository.</para></listitem>
<listitem><para><emphasis><filename>p4://</filename> -</emphasis> Fetches files from
a Perforce (<filename>p4</filename>) revision control repository.</para></listitem>
<listitem><para><emphasis><filename>ssh://</filename> -</emphasis> Fetches files from
a secure shell.</para></listitem>
<listitem><para><emphasis><filename>svn://</filename> -</emphasis> Fetches files from
a Subversion (<filename>svn</filename>) revision control repository.</para></listitem>
</itemizedlist>
</para>
<para>Here are some additional options worth mentioning:
<itemizedlist>
<listitem><para><emphasis><filename>unpack</filename> -</emphasis> Controls
whether or not to unpack the file if it is an archive.
The default action is to unpack the file.</para></listitem>
<listitem><para><emphasis><filename>subdir</filename> -</emphasis> Places the file
(or extracts its contents) into the specified
subdirectory.
This option is useful for unusual tarballs or other archives that
do not have their files already in a subdirectory within the archive.
</para></listitem>
<listitem><para><emphasis><filename>name</filename> -</emphasis> Specifies a
name to be used for association with <filename>SRC_URI</filename> checksums
when you have more than one file specified in <filename>SRC_URI</filename>.
</para></listitem>
<listitem><para><emphasis><filename>downloadfilename</filename> -</emphasis> Specifies
the filename used when storing the downloaded file.</para></listitem>
</itemizedlist>
</para>
</glossdef>
</glossentry>
<glossentry id='var-SRCDATE'><glossterm>SRCDATE</glossterm>
<glossdef>
<para>
The date of the source code used to build the package.
This variable applies only if the source was fetched from a Source Code Manager (SCM).
</para>
</glossdef>
</glossentry>
<glossentry id='var-SRCREV'><glossterm>SRCREV</glossterm>
<glossdef>
<para>
The revision of the source code used to build the package.
This variable applies only when using Subversion, Git, Mercurial and Bazaar.
If you want to build a fixed revision and you want
to avoid performing a query on the remote repository every time
BitBake parses your recipe, you should specify a <filename>SRCREV</filename> that is a
full revision identifier and not just a tag.
</para>
</glossdef>
</glossentry>
<glossentry id='var-SRCREV_FORMAT'><glossterm>SRCREV_FORMAT</glossterm>
<glossdef>
<para>
Helps construct valid
<link linkend='var-SRCREV'><filename>SRCREV</filename></link>
values when multiple source controlled URLs are used in
<link linkend='var-SRC_URI'><filename>SRC_URI</filename></link>.
</para>
<para>
The system needs help constructing these values under these
circumstances.
Each component in the <filename>SRC_URI</filename>
is assigned a name and these are referenced
in the <filename>SRCREV_FORMAT</filename> variable.
Consider an example with URLs named "machine" and "meta".
In this case, <filename>SRCREV_FORMAT</filename> could look
like "machine_meta" and those names would have the SCM
versions substituted into each position.
Only one <filename>AUTOINC</filename> placeholder is added
and if needed.
And, this placeholder is placed at the start of the
returned string.
</para>
</glossdef>
</glossentry>
<glossentry id='var-STAMP'><glossterm>STAMP</glossterm>
<glossdef>
<para>
Specifies the base path used to create recipe stamp files.
The path to an actual stamp file is constructed by evaluating this
string and then appending additional information.
</para>
</glossdef>
</glossentry>
<glossentry id='var-STAMPCLEAN'><glossterm>STAMPCLEAN</glossterm>
<glossdef>
<para>
Specifies the base path used to create recipe stamp files.
Unlike the
<link linkend='var-STAMP'><filename>STAMP</filename></link>
variable, <filename>STAMPCLEAN</filename> can contain
wildcards to match the range of files a clean operation
should remove.
BitBake uses a clean operation to remove any other stamps
it should be removing when creating a new stamp.
</para>
</glossdef>
</glossentry>
<glossentry id='var-SUMMARY'><glossterm>SUMMARY</glossterm>
<glossdef>
<para>
A short summary for the recipe, which is 72 characters or less.
</para>
</glossdef>
</glossentry>
<glossentry id='var-SVNDIR'><glossterm>SVNDIR</glossterm>
<glossdef>
<para>
The directory in which files checked out of a Subversion
system are stored.
</para>
</glossdef>
</glossentry>
</glossdiv>
<glossdiv id='var-glossary-t'><title>T</title>
<glossentry id='var-T'><glossterm>T</glossterm>
<glossdef>
<para>Points to a directory were BitBake places
temporary files, which consist mostly of task logs and
scripts, when building a particular recipe.
</para>
</glossdef>
</glossentry>
<glossentry id='var-TOPDIR'><glossterm>TOPDIR</glossterm>
<glossdef>
<para>
Points to the build directory.
BitBake automatically sets this variable.
</para>
</glossdef>
</glossentry>
</glossdiv>
<!--
<glossdiv id='var-glossary-u'><title>U</title>
</glossdiv>
<glossdiv id='var-glossary-v'><title>V</title>
</glossdiv>
<glossdiv id='var-glossary-w'><title>W</title>
</glossdiv>
<glossdiv id='var-glossary-x'><title>X</title>
</glossdiv>
<glossdiv id='var-glossary-y'><title>Y</title>
</glossdiv>
<glossdiv id='var-glossary-z'><title>Z</title>
</glossdiv>
-->
</glossary>
</chapter>
<!--
vim: expandtab tw=80 ts=4
-->
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