path: root/documentation/ref-manual/ref-variables.xml

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<!-- Dummy chapter -->
<chapter id='ref-variables-glos'>

<title>Variables Glossary</title>

<para>
    This chapter lists common variables used in the OpenEmbedded build system and gives an overview
    of their function and contents.
</para>

<glossary id='ref-variables-glossary'>


    <para>
       <link linkend='var-ALLOW_EMPTY'>A</link>
       <link linkend='var-B'>B</link>
       <link linkend='var-CFLAGS'>C</link>
       <link linkend='var-D'>D</link>
       <link linkend='var-ENABLE_BINARY_LOCALE_GENERATION'>E</link>
       <link linkend='var-FILES'>F</link>
<!--               <link linkend='var-glossary-g'>G</link> -->
       <link linkend='var-HOMEPAGE'>H</link>
       <link linkend='var-IMAGE_FEATURES'>I</link>
<!--               <link linkend='var-glossary-j'>J</link> -->
       <link linkend='var-KARCH'>K</link>
       <link linkend='var-LAYERDEPENDS'>L</link>
       <link linkend='var-MACHINE'>M</link>
<!--               <link linkend='var-glossary-n'>N</link> -->
       <link linkend='var-OE_TERMINAL'>O</link>
       <link linkend='var-P'>P</link>
<!--               <link linkend='var-glossary-q'>Q</link> -->
       <link linkend='var-RCONFLICTS'>R</link>
       <link linkend='var-S'>S</link>
       <link linkend='var-T'>T</link>
<!--               <link linkend='var-glossary-u'>U</link> -->
<!--               <link linkend='var-glossary-v'>V</link> -->
       <link linkend='var-WORKDIR'>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-ALLOW_EMPTY'><glossterm>ALLOW_EMPTY</glossterm>
            <glossdef>
                <para>
                   Specifies if an output package should still be produced if it is empty.
                   By default, BitBake does not produce empty packages.
                   This default behavior can cause issues when there is an
                   <link linkend='var-RDEPENDS'><filename>RDEPENDS</filename></link> or
                   some other runtime hard-requirement on the existence of the package.
                </para>

                <para>
                   Like all package-controlling variables, you must always use them in
                   conjunction with a package name override.
                   Here is an example:
                   <literallayout class='monospaced'>
     ALLOW_EMPTY_${PN} = "1"
                   </literallayout>
                </para>
            </glossdef>
         </glossentry>

         <glossentry id='var-AUTHOR'><glossterm>AUTHOR</glossterm>
            <glossdef>
                <para>The email address used to contact the original author
                    or authors in order to send patches and forward bugs.</para>
            </glossdef>
         </glossentry>

        <glossentry id='var-AUTOREV'><glossterm>AUTOREV</glossterm>
            <glossdef>
                <para>When <filename><link linkend='var-SRCREV'>SRCREV</link></filename>
                    is set to the value of this variable, it specifies to use the latest
                    source revision in the repository.
                    Here is an example:
                    <literallayout class='monospaced'>
     SRCREV = "${AUTOREV}"
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

    </glossdiv>

    <glossdiv id='var-glossary-b'><title>B</title>

        <glossentry id='var-B'><glossterm>B</glossterm>
            <glossdef>
                <para>
                    The <ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>Build Directory</ulink>.
                    The OpenEmbedded build system places generated objects into the Build Directory
                    during a recipe's build process.
                    By default, this directory is the same as the <link linkend='var-S'><filename>S</filename></link>
                    directory:
                    <literallayout class='monospaced'>
     B = "${WORKDIR}/${BPN}/{PV}/"
                    </literallayout>
                    You can separate the (<filename>S</filename>) directory and the directory pointed to
                    by the <filename>B</filename> variable.
                    Most Autotools-based recipes support separating these directories.
                    The build system defaults to using separate directories for <filename>gcc</filename>
                    and some kernel recipes.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-BAD_RECOMMENDATIONS'><glossterm>BAD_RECOMMENDATIONS</glossterm>
            <glossdef>
                <para>
                    A list of packages not to install despite being recommended by a recipe.
                    Support for this variable exists only when using the
                    IPK packaging backend.
                </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>

                <para>
                    You can change the default behavior by setting this
                    variable to "1" in the <filename>local.conf</filename>
                    file in the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>Build Directory</ulink>
                    as follows:
                    <literallayout class='monospaced'>
     BB_DANGLINGAPPENDS_WARNONLY = "1"
                    </literallayout>
                </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.
                    To enable monitoring, add the <filename>BB_DISKMON_DIRS</filename>
                    variable to your <filename>conf/local.conf</filename> file found in the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>Build Directory</ulink>.
                    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 in the
                      conf/local.conf file.

        &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 provide
                    the <link linkend='var-BB_DISKMON_WARNINTERVAL'><filename>BB_DISKMON_WARNINTERVAL</filename></link> variable
                    in the <filename>conf/local.conf</filename>.
                    This example causes the build system to immediately
                    abort when either the disk space in <filename>${TMPDIR}</filename> drops
                    below 1 Gbyte or the available free inodes drops below
                    100 Kbytes.
                    Because two directories are provided with the variable, the
                    build system also issue a
                    warning when the disk space in the
                    <filename>${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>${<link linkend='var-TMPDIR'>TMPDIR</link>}</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.
                    To set these intervals, define the variable in your
                    <filename>conf/local.conf</filename> file in the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>Build Directory</ulink>.
                </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,${SSTATE_DIR},1G,100K"
     BB_DISKMON_WARNINTERVAL = "50M,5K"
                    </literallayout>
                    These variables cause the OpenEmbedded build system to
                    issue subsequent warnings each time the available
                    disk space further reduces by 50 Mbytes or the number
                    of free inodes further reduces by 5 Kbytes in the
                    <filename>${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-BBCLASSEXTEND'><glossterm>BBCLASSEXTEND</glossterm>
            <glossdef>
                <para>
                    Allows you to extend a recipe so that it builds variants of the software.
                    Common variants for recipes exist such as "natives" like <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 <link linkend='var-MACHINE'><filename>MACHINE</filename></link>;
                    "nativesdk", which targets the SDK machine instead of <filename>MACHINE</filename>;
                    and "mulitlibs" in the form "<filename>multilib:&lt;multilib_name&gt;</filename>".
                </para>

                <para>
                    To build a different variant of the recipe with a minimal amount of code, it usually
                    is as simple as adding the following to your recipe:
                    <literallayout class='monospaced'>
     BBCLASSEXTEND =+ "native nativesdk"
     BBCLASSEXTEND =+ "multilib:&lt;multilib_name&gt;"
                    </literallayout>
                </para>
             </glossdef>
        </glossentry>

        <glossentry id='var-BBMASK'><glossterm>BBMASK</glossterm>
            <glossdef>
                <para>
                    Prevents BitBake from processing recipes and recipe
                    append files.
                    Use the <filename>BBMASK</filename> variable from within the
                    <filename>conf/local.conf</filename> file found
                    in the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>Build Directory</ulink>.
                </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 the expression.
                    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 value you provide is passed to Python's regular
                    expression compiler.
                    The expression is 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,
                    use the vertical bar to separate the 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 .= "|.*openldap"
     BBMASK .= "|.*opencv"
     BBMASK .= "|.*lzma"
                    </literallayout>
                    Notice how the vertical bar is used to append the fragments.
                    <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-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-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 will append 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 used by BitBake to build software.</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-BBPATH'><glossterm>BBPATH</glossterm>
            <glossdef>
                <para>Used by BitBake to locate <filename>.bbclass</filename> and configuration files.
                    This variable is analogous to the <filename>PATH</filename> variable.</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-BBINCLUDELOGS'><glossterm>BBINCLUDELOGS</glossterm>
            <glossdef>
                <para>Variable that controls how BitBake displays logs on build failure.</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 <ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>Build Directory</ulink>.
                    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 \
       "

     BBLAYERS_NON_REMOVABLE ?= " \
       /home/scottrif/poky/meta \
       /home/scottrif/poky/meta-yocto \
       "
                    </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_NON_REMOVABLE'><glossterm>BBLAYERS_NON_REMOVABLE</glossterm>
            <glossdef>
Core layer for images cannot be removed
                <para>Lists core layers that cannot be removed from the
                    <filename>bblayers.conf</filename> file.
                    In order for BitBake to build your image, your
                    <filename>bblayers.conf</filename> file must include the
                    <filename>meta</filename> and <filename>meta-yocto</filename>
                    core layers.
                    Here is an example that shows these two layers listed in
                    the <filename>BBLAYERS_NON_REMOVABLE</filename> statement:
                    <literallayout class='monospaced'>
     BBLAYERS = " \
       /home/scottrif/poky/meta \
       /home/scottrif/poky/meta-yocto \
       /home/scottrif/poky/meta-yocto-bsp \
       /home/scottrif/poky/meta-mykernel \
       "

     BBLAYERS_NON_REMOVABLE ?= " \
       /home/scottrif/poky/meta \
       /home/scottrif/poky/meta-yocto \
       "
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-BP'><glossterm>BP</glossterm>
            <glossdef>
                <para>The base recipe name and version but without any special
                    recipe name suffix (i.e. <filename>-native</filename>, <filename>lib64-</filename>,
                    and so forth).
                    <filename>BP</filename> is comprised of the following:
                    <literallayout class="monospaced">
     ${BPN}-${PV}
                    </literallayout></para>
            </glossdef>
        </glossentry>

        <glossentry id='var-BPN'><glossterm>BPN</glossterm>
            <glossdef>
                <para>The bare name of the recipe.
                    This variable is a version of the <link linkend='var-PN'><filename>PN</filename></link> variable
                    but removes common suffixes such as "-native" and "-cross" as well
                    as removes common prefixes such as multilib's "lib64-" and "lib32-".
                    The exact list of suffixes removed is specified by the
                    <link linkend='var-SPECIAL_PKGSUFFIX'><filename>SPECIAL_PKGSUFFIX</filename></link> variable.
                    The exact list of prefixes removed is specified by the
                    <link linkend='var-MLPREFIX'><filename>MLPREFIX</filename></link> variable.
                    Prefixes are removed for <filename>multilib</filename>
                    and <filename>nativesdk</filename> cases.</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-BUILDDIR'><glossterm>BUILDDIR</glossterm>
            <glossdef>
                <para>Points to the location of the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>Build Directory</ulink>.
                    You can define this directory indirectly through the
                    <link linkend='structure-core-script'><filename>&OE_INIT_FILE;</filename></link>
                    script by passing in a Build Directory path when you run the
                    script.
                    If you run the script and do not provide a Build Directory
                    path, the <filename>BUILDDIR</filename> defaults to
                    <filename>build</filename> in the current directory.
                </para>
            </glossdef>
        </glossentry>
    </glossdiv>

    <glossdiv id='var-glossary-c'><title>C</title>

        <glossentry id='var-CFLAGS'><glossterm>CFLAGS</glossterm>
            <glossdef>
                <para>
                    Flags passed to the C compiler for the target system.
                    This variable evaluates to the same as
                    <filename><link linkend='var-TARGET_CFLAGS'>TARGET_CFLAGS</link></filename>.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-COMBINED_FEATURES'><glossterm>COMBINED_FEATURES</glossterm>
            <glossdef>
                <para>A set of features common between
                    <link linkend='var-MACHINE_FEATURES'><filename>MACHINE_FEATURES</filename></link>
                    and <link linkend='var-DISTRO_FEATURES'><filename>DISTRO_FEATURES</filename></link>.
                    See the glossary descriptions for these variables for more information.</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-COMPATIBLE_HOST'><glossterm>COMPATIBLE_HOST</glossterm>
            <glossdef>
                <para>A regular expression that resolves to one or more hosts
                    (when the recipe is native) or one or more targets (when
                    the recipe is non-native) with which a recipe is compatible.
                    The regular expression is matched against
                    <link linkend="var-HOST_SYS"><filename>HOST_SYS</filename></link>.
                    You can use the variable to stop recipes from being built
                    for classes of systems with which the recipes are not
                    compatible.
                    Stopping these builds is particularly useful with kernels.
                    The variable also helps to increase parsing speed
                    since the build system skips parsing recipes not
                    compatible with the current system.</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-COMPATIBLE_MACHINE'><glossterm>COMPATIBLE_MACHINE</glossterm>
            <glossdef>
                <para>A regular expression that resolves to one or more
                    target machines with which a recipe is compatible.
                    The regular expression is matched against
                    <link linkend="var-MACHINEOVERRIDES"><filename>MACHINEOVERRIDES</filename></link>.
                    You can use the variable to stop recipes from being built
                    for machines with which the recipes are not compatible.
                    Stopping these builds is particularly useful with kernels.
                    The variable also helps to increase parsing speed
                    since the build system skips parsing recipes not
                    compatible with the current machine.</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-CONFFILES'><glossterm>CONFFILES</glossterm>
            <glossdef>
                <para>
                    Identifies editable or configurable files that are part of a package.
                    If the Package Management System (PMS) is being used to update
                    packages on the target system, it is possible that
                    configuration files you have changed after the original installation
                    and that you now want to remain unchanged are overwritten.
                    In other words, editable files might exist in the package that you do not
                    want reset as part of the package update process.
                    You can use the <filename>CONFFILES</filename> variable to list the files in the
                    package that you wish to prevent the PMS from overwriting during this update process.
                </para>

                <para>
                    To use the <filename>CONFFILES</filename> variable, provide a package name
                    override that identifies the resulting package.
                    Then, provide a space-separated list of files.
                    Here is an example:
                    <literallayout class='monospaced'>
  CONFFILES_${PN} += "${sysconfdir}/file1 \
     ${sysconfdir}/file2 ${sysconfdir}/file3"
                    </literallayout>
                </para>

                <para>
                    A relationship exists between the <filename>CONFFILES</filename> and
                    <filename><link linkend='var-FILES'>FILES</link></filename> variables.
                    The files listed within <filename>CONFFILES</filename> must be a subset of
                    the files listed within <filename>FILES</filename>.
                    Because the configuration files you provide with <filename>CONFFILES</filename>
                    are simply being identified so that the PMS will not overwrite them,
                    it makes sense that
                    the files must already be included as part of the package through the
                    <filename>FILES</filename> variable.
                </para>

                <note>
                    When specifying paths as part of the <filename>CONFFILES</filename> variable,
                    it is good practice to use appropriate path variables.
                    For example, <filename>${sysconfdir}</filename> rather than
                    <filename>/etc</filename> or <filename>${bindir}</filename> rather
                    than <filename>/usr/bin</filename>.
                    You can find a list of these variables at the top of the
                    <filename>/meta/conf/bitbake.conf</filename> file in the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#source-directory'>Source Directory</ulink>.
                </note>
            </glossdef>
        </glossentry>

        <glossentry id='var-CONFIG_SITE'><glossterm>CONFIG_SITE</glossterm>
            <glossdef>
                <para>
                    A list of files that contains <filename>autoconf</filename> test results relevant
                    to the current build.
                    This variable is used by the Autotools utilities when running
                    <filename>configure</filename>.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-CORE_IMAGE_EXTRA_INSTALL'><glossterm>CORE_IMAGE_EXTRA_INSTALL</glossterm>
            <glossdef>
                <para>
                    Specifies the list of packages to be added to the image.
                    You should only set this variable in the
                    <filename>local.conf</filename> configuration file found
                    in the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>Build Directory</ulink>.
                </para>

                <para>
                    This variable replaces <filename>POKY_EXTRA_INSTALL</filename>, which is no longer supported.
                </para>
            </glossdef>
        </glossentry>

    </glossdiv>

    <glossdiv id='var-glossary-d'><title>D</title>

        <glossentry id='var-D'><glossterm>D</glossterm>
            <glossdef>
                <para>The destination directory.</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-DEBUG_BUILD'><glossterm>DEBUG_BUILD</glossterm>
            <glossdef>
                <para>
                    Specifies to build packages with debugging information.
                    This influences the value of the
                    <filename><link linkend='var-SELECTED_OPTIMIZATION'>SELECTED_OPTIMIZATION</link></filename>
                    variable.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-DEBUG_OPTIMIZATION'><glossterm>DEBUG_OPTIMIZATION</glossterm>
            <glossdef>
                <para>
                    The options to pass in
                    <filename><link linkend='var-TARGET_CFLAGS'>TARGET_CFLAGS</link></filename>
                    and <filename><link linkend='var-CFLAGS'>CFLAGS</link></filename> when compiling
                    a system for debugging.
                    This variable defaults to "-O -fno-omit-frame-pointer -g".
                </para>
            </glossdef>
        </glossentry>

        <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 the 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).
                    The system ensures that all the dependencies listed
                    have been built and have their contents in the appropriate
                    sysroots before the recipe's configure task is executed.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-DESCRIPTION'><glossterm>DESCRIPTION</glossterm>
            <glossdef>
                <para>The package description used by package managers.
                      If not set, <filename>DESCRIPTION</filename> takes
                      the value of the
                      <link linkend='var-SUMMARY'><filename>SUMMARY</filename></link>
                      variable.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-DESTDIR'><glossterm>DESTDIR</glossterm>
            <glossdef>
                <para>the destination directory.</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-DISTRO'><glossterm>DISTRO</glossterm>
            <glossdef>
                <para>
                    The short name of the distribution.
                    This variable corresponds to a file with the
                    extension <filename>.conf</filename>
                    located in a <filename>conf/distro</filename> directory
                    within the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#metadata'>Metadata</ulink>
                    that contains the distribution configuration.
                    The value must not contain spaces, and is typically all lower-case.
                </para>
                <para>
                    If the variable is blank, a set of default configuration
                    will be used, which is specified
                    within <filename>meta/conf/distro/defaultsetup.conf</filename>.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-DISTRO_EXTRA_RDEPENDS'><glossterm>DISTRO_EXTRA_RDEPENDS</glossterm>
            <glossdef>
                <para>
                    Specifies a list of distro-specific packages to add to all images.
                    This variable takes affect through
                    <filename>packagegroup-base</filename> so the
                    variable only really applies to the more full-featured
                    images that include <filename>packagegroup-base</filename>.
                    You can use this variable to keep distro policy out of
                    generic images.
                    As with all other distro variables, you set this variable
                    in the distro <filename>.conf</filename> file.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-DISTRO_EXTRA_RRECOMMENDS'><glossterm>DISTRO_EXTRA_RRECOMMENDS</glossterm>
            <glossdef>
                <para>
                    Specifies a list of distro-specific packages to add to all images
                    if the packages exist.
                    The packages might not exist or be empty (e.g. kernel modules).
                    The list of packages are automatically installed but you can
                    remove them.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-DISTRO_FEATURES'><glossterm>DISTRO_FEATURES</glossterm>
            <glossdef>
                <para>The features enabled for the distribution.
                    For a list of supported features that ship with the
                    Yocto Project, see the
                    "<link linkend='ref-features-distro'>Distro</link>"
                    section.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-DISTRO_FEATURES_BACKFILL'><glossterm>DISTRO_FEATURES_BACKFILL</glossterm>
            <glossdef>
                <para>Features to be added to
                    <filename><link linkend='var-DISTRO_FEATURES'>DISTRO_FEATURES</link></filename>
                    if not also present in
                    <filename><link linkend='var-DISTRO_FEATURES_BACKFILL_CONSIDERED'>DISTRO_FEATURES_BACKFILL_CONSIDERED</link></filename>.
                </para>

                <para>
                    This variable is set in the <filename>meta/conf/bitbake.conf</filename> file.
                    It is not intended to be user-configurable.
                    It is best to just reference the variable to see which distro features are
                    being backfilled for all distro configurations.
                    See the <link linkend='ref-features-backfill'>Feature backfilling</link> section for
                    more information.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-DISTRO_FEATURES_BACKFILL_CONSIDERED'><glossterm>DISTRO_FEATURES_BACKFILL_CONSIDERED</glossterm>
            <glossdef>
                <para>Features from
                    <filename><link linkend='var-DISTRO_FEATURES_BACKFILL'>DISTRO_FEATURES_BACKFILL</link></filename>
                    that should not be backfilled (i.e. added to
                    <filename><link linkend='var-DISTRO_FEATURES'>DISTRO_FEATURES</link></filename>)
                    during the build.
                    See the "<link linkend='ref-features-backfill'>Feature Backfilling</link>" section for
                    more information.
                    </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-DISTRO_NAME'><glossterm>DISTRO_NAME</glossterm>
            <glossdef>
                <para>The long name of the distribution.</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-DISTRO_PN_ALIAS'><glossterm>DISTRO_PN_ALIAS</glossterm>
            <glossdef>
                <para>Alias names used for the recipe in various Linux distributions.</para>
                <para>See the
                    "<ulink url='&YOCTO_DOCS_DEV_URL;#usingpoky-configuring-DISTRO_PN_ALIAS'>Handling
                    a Package Name Alias</ulink>" section in the Yocto Project Development
                    Manual for more information.</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-DISTRO_VERSION'><glossterm>DISTRO_VERSION</glossterm>
            <glossdef>
                <para>the version of the distribution.</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-DISTROOVERRIDES'><glossterm>DISTROOVERRIDES</glossterm>
            <glossdef>
                <para>
                    This variable lists overrides specific to the current
                    distribution.
                    By default, the variable list includes the value of the
                    <filename><link linkend='var-DISTRO'>DISTRO</link></filename>
                    variable.
                    You can extend the variable to apply any variable overrides
                    you want as part of the distribution and are not
                    already in <filename>OVERRIDES</filename> through
                    some other means.
                </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.
                    You can set this directory by defining the <filename>DL_DIR</filename>
                    variable in the <filename>/conf/local.conf</filename> file.
                    This directory is self-maintaining and you should not have
                    to touch it.
                    By default, the directory is <filename>downloads</filename> in the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>Build Directory</ulink>.
                    <literallayout class='monospaced'>
     #DL_DIR ?= "${TOPDIR}/downloads"
                    </literallayout>
                    To specify a different download directory, simply uncomment the line
                    and provide your directory.
                </para>

                <para>
                    During a first build, the system downloads many different source code
                    tarballs from various upstream projects.
                    Downloading can take a while, particularly if your network
                    connection is slow.
                    Tarballs are all stored in the directory defined by
                    <filename>DL_DIR</filename> and the build system looks there first
                    to find source tarballs.
                    <note>
                        When wiping and rebuilding, you can preserve this directory to speed
                        up this part of subsequent builds.
                    </note>
                </para>

                <para>
                    You can safely share this directory between multiple builds on the
                    same development machine.
                    For additional information on how the build process gets
                    source files when working behind a firewall or proxy server,
                    see this specific question in the
                    "<link linkend='how-does-the-yocto-project-obtain-source-code-and-will-it-work-behind-my-firewall-or-proxy-server'>FAQ</link>"
                    chapter.
                </para>
            </glossdef>

        </glossentry>
    </glossdiv>

    <glossdiv id='var-glossary-e'><title>E</title>

        <glossentry id='var-ENABLE_BINARY_LOCALE_GENERATION'><glossterm>ENABLE_BINARY_LOCALE_GENERATION</glossterm>
            <glossdef>
                <para></para>
                <para>Variable that controls which locales for
                    <filename>eglibc</filename> are generated during the
                    build (useful if the target device has 64Mbytes
                    of RAM or less).</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-EXTENDPE'><glossterm>EXTENDPE</glossterm>
            <glossdef>
                <para>
                    Used with file and pathnames to create a prefix for a recipe's
                    version based on the recipe's
                    <link linkend='var-PE'><filename>PE</filename></link> value.
                    If <filename>PE</filename> is set and greater than zero for a recipe,
                    <filename>EXTENDPE</filename> becomes that value (e.g if
                    <filename>PE</filename> is equal to "1" then <filename>EXTENDPE</filename>
                    becomes "1_").
                    If a recipe's <filename>PE</filename> is not set (the default) or is equal to
                    zero, <filename>EXTENDPE</filename> becomes "".</para>
                    <para>See the <link linkend='var-STAMP'><filename>STAMP</filename></link>
                    variable for an example.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-EXTRA_IMAGE_FEATURES'><glossterm>EXTRA_IMAGE_FEATURES</glossterm>
            <glossdef>
                <para>
                    The list of additional features to include in an image.
                    Typically, you configure this variable in your
                    <filename>local.conf</filename> file, which is found in the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>Build Directory</ulink>.
                    Although you can use this variable from within a recipe,
                    best practices dictate that you do not.
                    <note>
                        To enable primary features from within the image
                        recipe, use the
                        <link linkend='var-IMAGE_FEATURES'><filename>IMAGE_FEATURES</filename></link>
                        variable.
                    </note>
                </para>

                <para>
                    Here are some examples of features you can add:
                    <literallayout class='monospaced'>
"dbg-pkgs" - Adds -dbg packages for all installed packages
             including symbol information for debugging and
             profiling.

"debug-tweaks" - Makes an image suitable for development.
                 For example, ssh root access has a blank
                 password.  You should remove this feature
                 before you produce a production image.

"dev-pkgs" - Adds -dev packages for all installed packages.
             This is useful if you want to develop against
             the libraries in the image.

"read-only-rootfs" - Creates an image whose root
                     filesystem is read-only. See the
                     "<ulink url='&YOCTO_DOCS_DEV_URL;#creating-a-read-only-root-filesystem'>Creating a Read-Only Root Filesystem</ulink>"
                     section in the Yocto Project
                     Development Manual for more
                     information

"tools-debug" - Adds debugging tools such as gdb and
                strace.

"tools-profile" - Adds profiling tools such as oprofile,
                  exmap, lttng and valgrind (x86 only).

"tools-sdk" - Adds development tools such as gcc, make,
              pkgconfig and so forth.

"tools-testapps" - Adds useful testing tools such as
                   ts_print, aplay, arecord and so
                   forth.

                    </literallayout>
                </para>

                <para>
                    For a complete list of image features that ships with the
                    Yocto Project, see the
                    "<link linkend="ref-features-image">Images</link>"
                    section.
                </para>

                <para>
                    For an example that shows how to customize your image by
                    using this variable, see the
                    "<ulink url='&YOCTO_DOCS_DEV_URL;#usingpoky-extend-customimage-imagefeatures'>Customizing Images Using Custom <filename>IMAGE_FEATURES</filename> and <filename>EXTRA_IMAGE_FEATURES</filename></ulink>"
                    section in the Yocto Project Development Manual.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-EXTRA_IMAGEDEPENDS'><glossterm>EXTRA_IMAGEDEPENDS</glossterm>
            <glossdef>
                <para>A list of recipes to build that do not provide packages
                    for installing into the root filesystem.
                </para>
                <para>Sometimes a recipe is required to build the final image but is not
                    needed in the root filesystem.
                    You can use the <filename>EXTRA_IMAGEDEPENDS</filename> variable to
                    list these recipes and thus, specify the dependencies.
                    A typical example is a required bootloader in a machine configuration.
                </para>
                <note>
                    To add packages to the root filesystem, see the various
                    <filename>*<link linkend='var-RDEPENDS'>RDEPENDS</link></filename>
                    and <filename>*<link linkend='var-RRECOMMENDS'>RRECOMMENDS</link></filename>
                    variables.
                </note>
            </glossdef>
        </glossentry>

        <glossentry id='var-EXTRA_OECMAKE'><glossterm>EXTRA_OECMAKE</glossterm>
            <glossdef>
                <para>Additional <filename>cmake</filename> options.</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-EXTRA_OECONF'><glossterm>EXTRA_OECONF</glossterm>
            <glossdef>
                <para>Additional <filename>configure</filename> script options.</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-EXTRA_OEMAKE'><glossterm>EXTRA_OEMAKE</glossterm>
            <glossdef>
                <para>Additional GNU <filename>make</filename> options.</para>
            </glossdef>
        </glossentry>

    </glossdiv>

    <glossdiv id='var-glossary-f'><title>F</title>

        <glossentry id='var-FILES'><glossterm>FILES</glossterm>
            <glossdef>
                <para>
                    The list of directories or files that are placed in packages.
                </para>

                <para>
                    To use the <filename>FILES</filename> variable, provide a package name
                    override that identifies the resulting package.
                    Then, provide a space-separated list of files or paths that identifies the
                    files you want included as part of the resulting package.
                    Here is an example:
                    <literallayout class='monospaced'>
  FILES_${PN} += "${bindir}/mydir1/ ${bindir}/mydir2/myfile"
                    </literallayout>
                </para>

                <note>
                    When specifying paths as part of the <filename>FILES</filename> variable,
                    it is good practice to use appropriate path variables.
                    For example, <filename>${sysconfdir}</filename> rather than
                    <filename>/etc</filename> or <filename>${bindir}</filename> rather
                    than <filename>/usr/bin</filename>.
                    You can find a list of these variables at the top of the
                    <filename>/meta/conf/bitbake.conf</filename> file in the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#source-directory'>Source Directory</ulink>.
                </note>

                <para>
                    If some of the files you provide with the <filename>FILES</filename> variable
                    are editable and you know they should not be
                    overwritten during the package update process by the Package Management
                    System (PMS), you can identify these files so that the PMS will not
                    overwrite them.
                    See the <filename><link linkend='var-CONFFILES'>CONFFILES</link></filename>
                    variable for information on how to identify these files to the PMS.
                </para>

            </glossdef>
        </glossentry>

        <glossentry id='var-FILESEXTRAPATHS'><glossterm>FILESEXTRAPATHS</glossterm>
            <glossdef>
                <para>
                    Extends the search path the OpenEmbedded build system uses
                    when looking for files and patches as it processes recipes
                    and append files.
                    The default directories BitBake uses when it processes
                    recipes are initially defined by the
                    <link linkend='var-FILESPATH'><filename>FILESPATH</filename></link>
                    variable.
                    You can extend <filename>FILESPATH</filename> variable
                    by using <filename>FILESEXTRAPATHS</filename>.
                </para>

                <para>
                    Best practices dictate that you accomplish this by using
                    <filename>FILESEXTRAPATHS</filename> from within a
                    <filename>.bbappend</filename> file and that you prepend
                    paths as follows:
                    <literallayout class='monospaced'>
     FILESEXTRAPATHS_prepend := "${THISDIR}/${PN}:"
                    </literallayout>
                    In the above example, the build system first looks for files
                    in a directory that has the same name as the corresponding
                    append file.
                    <note>
                        <para>When extending <filename>FILESEXTRAPATHS</filename>,
                        be sure to use the immediate expansion
                        (<filename>:=</filename>) operator.
                        Immediate expansion makes sure that BitBake evaluates
                        <link linkend='var-THISDIR'><filename>THISDIR</filename></link>
                        at the time the directive is encountered rather than at
                        some later time when expansion might result in a
                        directory that does not contain the files you need.
                        </para>
                        <para>Also, include the trailing separating colon
                        character if you are prepending.
                        The trailing colon character is necessary because you
                        are directing BitBake to extend the path by prepending
                        directories to the search path.</para>
                    </note>
                    Here is another common use:
                    <literallayout class='monospaced'>
     FILESEXTRAPATHS_prepend := "${THISDIR}/files:"
                    </literallayout>
                    In this example, the build system extends the
                    <filename>FILESPATH</filename> variable to include a
                    directory named <filename>files</filename> that is in the
                    same directory as the corresponding append file.
                </para>

                <para>
                    Here is a final example that specifically adds three paths:
                    <literallayout class='monospaced'>
     FILESEXTRAPATHS_prepend := "path_1:path_2:path_3:"
                    </literallayout>
                </para>

                <para>
                    By prepending paths in <filename>.bbappend</filename>
                    files, you allow multiple append files that reside in
                    different layers but are used for the same recipe to
                    correctly extend the path.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-FILESOVERRIDES'><glossterm>FILESOVERRIDES</glossterm>
            <glossdef>
                <para>
                    A subset of <link linkend='var-OVERRIDES'><filename>OVERRIDES</filename></link>
                    used by the OpenEmbedded build system for creating
                    <link linkend='var-FILESPATH'><filename>FILESPATH</filename></link>.
                    You can find more information on how overrides are handled
                    in the BitBake Manual that is located at
                    <filename>bitbake/doc/manual</filename> in the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#source-directory'>Source Directory</ulink>.
                </para>

                <para>
                    By default, the <filename>FILESOVERRIDES</filename>
                    variable is defined as:
                    <literallayout class='monospaced'>
     FILESOVERRIDES = "${TRANSLATED_TARGET_ARCH}:${MACHINEOVERRIDES}:${DISTROOVERRIDES}"
                    </literallayout>

                    <note>
                        Do not hand-edit the <filename>FILESOVERRIDES</filename>
                        variable.
                        The values match up with expected overrides and are
                        used in an expected manner by the build system.
                    </note>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-FILESPATH'><glossterm>FILESPATH</glossterm>
            <glossdef>
                <para>
                    The default set of directories the OpenEmbedded build system
                    uses when searching for patches and files.
                    During the build process, BitBake searches each directory in
                    <filename>FILESPATH</filename> in the specified order when
                    looking for files and patches specified by each
                    <filename>file://</filename> URI in a recipe.
                </para>

                <para>
                    The default value for the <filename>FILESPATH</filename>
                    variable is defined in the <filename>base.bbclass</filename>
                    class found in <filename>meta/classes</filename> in the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#source-directory'>Source Directory</ulink>:
                    <literallayout class='monospaced'>
     FILESPATH = "${@base_set_filespath(["${FILE_DIRNAME}/${BP}", \
        "${FILE_DIRNAME}/${BPN}", "${FILE_DIRNAME}/files"], d)}"
                    </literallayout>
                    <note>
                        Do not hand-edit the <filename>FILESPATH</filename>
                        variable.
                        If you want the build system to look in directories
                        other than the defaults, extend the
                        <filename>FILESPATH</filename> variable by using the
                        <link linkend='var-FILESEXTRAPATHS'><filename>FILESEXTRAPATHS</filename></link>
                        variable.
                    </note>
                    Be aware that the default <filename>FILESPATH</filename>
                    directories do not map to directories in custom layers
                    where append files (<filename>.bbappend</filename>)
                    are used.
                    If you want the build system to find patches or files
                    that reside with your append files, you need to extend
                    the <filename>FILESPATH</filename> variable by using
                    the
                    <link linkend='var-FILESEXTRAPATHS'><filename>FILESEXTRAPATHS</filename></link>
                    variable.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-FILESYSTEM_PERMS_TABLES'><glossterm>FILESYSTEM_PERMS_TABLES</glossterm>
            <glossdef>
                <para>Allows you to define your own file permissions settings table as part of
                    your configuration for the packaging process.
                    For example, suppose you need a consistent set of custom permissions for
                    a set of groups and users across an entire work project.
                    It is best to do this in the packages themselves but this is not always
                    possible.
                </para>
                <para>
                    By default, the OpenEmbedded build system uses the <filename>fs-perms.txt</filename>, which
                    is located in the <filename>meta/files</filename> folder in the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#source-directory'>Source Directory</ulink>.
                    If you create your own file permissions setting table, you should place it in your
                    layer or the distros layer.
                </para>
                <para>
                    You define the <filename>FILESYSTEM_PERMS_TABLES</filename> variable in the
                    <filename>conf/local.conf</filename> file, which is found in the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>Build Directory</ulink>, to
                    point to your custom <filename>fs-perms.txt</filename>.
                    You can specify more than a single file permissions setting table.
                    The paths you specify to these files must be defined within the
                    <link linkend='var-BBPATH'><filename>BBPATH</filename></link> variable.
                </para>
                <para>
                    For guidance on how to create your own file permissions settings table file,
                    examine the existing <filename>fs-perms.txt</filename>.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-FULL_OPTIMIZATION'><glossterm>FULL_OPTIMIZATION</glossterm>
            <glossdef>
                <para>
                    The options to pass in
                    <filename><link linkend='var-TARGET_CFLAGS'>TARGET_CFLAGS</link></filename>
                    and <filename><link linkend='var-CFLAGS'>CFLAGS</link></filename>
                    when compiling an optimized system.
                    This variable defaults to
                    "-fexpensive-optimizations -fomit-frame-pointer -frename-registers -O2".
                </para>
            </glossdef>
        </glossentry>

    </glossdiv>

<!--            <glossdiv id='var-glossary-g'><title>G</title>-->
<!--            </glossdiv>-->

    <glossdiv id='var-glossary-h'><title>H</title>

        <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>

        <glossentry id='var-HOST_SYS'><glossterm>HOST_SYS</glossterm>
            <glossdef>
                <para>
                    Specifies the system, including the architecture and the
                    operating system, for with the build is occurring
                    in the context of the current
                    recipe.
                    The OpenEmbedded build system automatically sets this
                    variable.
                    You do not need to set the variable yourself.
                </para>

                <para>
                    Here are two examples:
                    <itemizedlist>
                        <listitem><para>Given a native recipe on a 32-bit
                            x86 machine running Linux, the value is
                            "i686-linux".
                            </para></listitem>
                        <listitem><para>Given a recipe being built for a
                            little-endian MIPS target running Linux,
                            the value might be "mipsel-linux".
                            </para></listitem>
                    </itemizedlist>
                </para>
            </glossdef>
        </glossentry>

    </glossdiv>

    <glossdiv id='var-glossary-i'><title>I</title>

        <glossentry id='var-IMAGE_FEATURES'><glossterm>IMAGE_FEATURES</glossterm>
            <glossdef>
                <para>
                    The primary list of features to include in an image.
                    Typically, you configure this variable in an image recipe.
                    Although you can use this variable from your
                    <filename>local.conf</filename> file, which is found in the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>Build Directory</ulink>,
                    best practices dictate that you do not.
                    <note>
                        To enable extra features from outside the image recipe,
                        use the
                        <filename><link linkend='var-EXTRA_IMAGE_FEATURES'>EXTRA_IMAGE_FEATURES</link></filename> variable.
                    </note>
                    For a list of image features that ships with the Yocto
                    Project, see the
                    "<link linkend="ref-features-image">Images</link>"
                    section.
                </para>

                <para>
                    For example that shows how to customize your image by
                    using this variable, see the
                    "<ulink url='&YOCTO_DOCS_DEV_URL;#usingpoky-extend-customimage-imagefeatures'>Customizing Images Using Custom <filename>IMAGE_FEATURES</filename> and <filename>EXTRA_IMAGE_FEATURES</filename></ulink>"
                    section in the Yocto Project Development Manual.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-IMAGE_FSTYPES'><glossterm>IMAGE_FSTYPES</glossterm>
            <glossdef>
                <para>Formats of root filesystem images that you want to have created.</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-IMAGE_INSTALL'><glossterm>IMAGE_INSTALL</glossterm>
            <glossdef>
                <para>
                    Specifies the packages to install into an image.
                    The <filename>IMAGE_INSTALL</filename> variable is a mechanism for an image
                    recipe and you should use it with care to avoid ordering issues.
                </para>

                <para>
                    Image recipes set <filename>IMAGE_INSTALL</filename> to specify the
                    packages to install into an image through <filename>image.bbclass</filename>.
                    Additionally, "helper" classes exist, such as <filename>core-image.bbclass</filename>,
                    that can take
                    <filename><link linkend='var-IMAGE_FEATURES'>IMAGE_FEATURES</link></filename> lists
                    and turn these into auto-generated entries in
                    <filename>IMAGE_INSTALL</filename> in addition to its default contents.
                </para>

                <para>
                    Using <filename>IMAGE_INSTALL</filename> with the <filename>+=</filename>
                    operator from the <filename>/conf/local.conf</filename> file or from within
                    an image recipe is not recommended as it can cause ordering issues.
                    Since <filename>core-image.bbclass</filename> sets <filename>IMAGE_INSTALL</filename>
                    to a default value using the <filename>?=</filename> operator, using a
                    <filename>+=</filename> operation against <filename>IMAGE_INSTALL</filename>
                    will result in unexpected behavior when used in
                    <filename>/conf/local.conf</filename>.
                    Furthermore, the same operation from with an image recipe may or may not
                    succeed depending on the specific situation.
                    In both these cases, the behavior is contrary to how most users expect
                    the <filename>+=</filename> operator to work.
                </para>

                <para>
                    When you use this variable, it is best to use it as follows:
                    <literallayout class='monospaced'>
     IMAGE_INSTALL_append = " package-name"
                    </literallayout>
                    Be sure to include the space between the quotation character and the start of the
                    package name.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-IMAGE_LINGUAS'><glossterm>IMAGE_LINGUAS</glossterm>
            <glossdef>
                <para>
                    Specifies the list of locales to install into the image
                    during the root filesystem construction process.
                    The OpenEmbedded build system automatically splits locale
                    files, which are used for localization, into separate
                    packages.
                    Setting the <filename>IMAGE_LINGUAS</filename> variable
                    ensures that any locale packages that correspond to packages
                    already selected for installation into the image are also
                    installed.
                    Here is an example:
                    <literallayout class='monospaced'>
     IMAGE_LINGUAS = "pt-br de-de"
                    </literallayout>
                    In this example, the build system ensures any Brazilian
                    Portuguese and German locale files that correspond to
                    packages in the image are installed (i.e.
                    <filename>*-locale-pt-br</filename>
                    and <filename>*-locale-de-de</filename> as well as
                    <filename>*-locale-pt</filename>
                    and <filename>*-locale-de</filename>, since some software
                    packages only provide locale files by language and not by
                    country-specific language).
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-IMAGE_OVERHEAD_FACTOR'><glossterm>IMAGE_OVERHEAD_FACTOR</glossterm>
            <glossdef>
                <para>
                    Defines a multiplier that the build system applies to the initial image
                    size for cases when the multiplier times the returned disk usage value
                    for the image is greater than the sum of
                    <filename><link linkend='var-IMAGE_ROOTFS_SIZE'>IMAGE_ROOTFS_SIZE</link></filename>
                    and
                    <filename><link linkend='var-IMAGE_ROOTFS_EXTRA_SPACE'>IMAGE_ROOTFS_EXTRA_SPACE</link></filename>.
                    The result of the multiplier applied to the initial image size creates
                    free disk space in the image as overhead.
                    By default, the build process uses a multiplier of 1.3 for this variable.
                    This default value results in 30% free disk space added to the image when this
                    method is used to determine the final generated image size.
                    You should be aware that post install scripts and the package management
                    system uses disk space inside this overhead area.
                    Consequently, the multiplier does not produce an image with
                    all the theoretical free disk space.
                    See <filename><link linkend='var-IMAGE_ROOTFS_SIZE'>IMAGE_ROOTFS_SIZE</link></filename>
                    for information on how the build system determines the overall image size.
                </para>

                <para>
                    The default 30% free disk space typically gives the image enough room to boot
                    and allows for basic post installs while still leaving a small amount of
                    free disk space.
                    If 30% free space is inadequate, you can increase the default value.
                    For example, the following setting gives you 50% free space added to the image:
                    <literallayout class='monospaced'>
     IMAGE_OVERHEAD_FACTOR = "1.5"
                    </literallayout>
                </para>

                <para>
                    Alternatively, you can ensure a specific amount of free disk space is added
                    to the image by using
                    <filename><link linkend='var-IMAGE_ROOTFS_EXTRA_SPACE'>IMAGE_ROOTFS_EXTRA_SPACE</link></filename>
                    the variable.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-IMAGE_ROOTFS_EXTRA_SPACE'><glossterm>IMAGE_ROOTFS_EXTRA_SPACE</glossterm>
            <glossdef>
                <para>
                    Defines additional free disk space created in the image in Kbytes.
                    By default, this variable is set to "0".
                    This free disk space is added to the image after the build system determines
                    the image size as described in
                    <filename><link linkend='var-IMAGE_ROOTFS_SIZE'>IMAGE_ROOTFS_SIZE</link></filename>.
                </para>

                <para>
                    This variable is particularly useful when you want to ensure that a
                    specific amount of free disk space is available on a device after an image
                    is installed and running.
                    For example, to be sure 5 Gbytes of free disk space is available, set the
                    variable as follows:
                    <literallayout class='monospaced'>
     IMAGE_ROOTFS_EXTRA_SPACE = "5242880"
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-IMAGE_ROOTFS_SIZE'><glossterm>IMAGE_ROOTFS_SIZE</glossterm>
            <glossdef>
                <para>
                    Defines the size in Kbytes for the generated image.
                    The OpenEmbedded build system determines the final size for the generated
                    image using an algorithm that takes into account the initial disk space used
                    for the generated image, a requested size for the image, and requested
                    additional free disk space to be added to the image.
                    Programatically, the build system determines the final size of the
                    generated image as follows:
                    <literallayout class='monospaced'>
    if (image-du * overhead) &lt; rootfs-size:
	internal-rootfs-size = rootfs-size + xspace
    else:
	internal-rootfs-size = (image-du * overhead) + xspace

    where:

      image-du = Returned value of the du command on
                 the image.

      overhead = IMAGE_OVERHEAD_FACTOR

      rootfs-size = IMAGE_ROOTFS_SIZE

      internal-rootfs-size = Initial root filesystem
                             size before any modifications.

      xspace = IMAGE_ROOTFS_EXTRA_SPACE
                    </literallayout>
                    See the <link linkend='var-IMAGE_OVERHEAD_FACTOR'><filename>IMAGE_OVERHEAD_FACTOR</filename></link>
                    and <link linkend='var-IMAGE_ROOTFS_EXTRA_SPACE'><filename>IMAGE_ROOTFS_EXTRA_SPACE</filename></link>
                    variables for related information.
<!--                    In the above example, <filename>overhead</filename> is defined by the
                    <filename><link linkend='var-IMAGE_OVERHEAD_FACTOR'>IMAGE_OVERHEAD_FACTOR</link></filename>
                    variable, <filename>xspace</filename> is defined by the
                    <filename><link linkend='var-IMAGE_ROOTFS_EXTRA_SPACE'>IMAGE_ROOTFS_EXTRA_SPACE</link></filename>
                    variable, and <filename>du</filename> is the results of the disk usage command
                    on the initially generated image. -->
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-INC_PR'><glossterm>INC_PR</glossterm>
            <glossdef>
                <para>Helps define the recipe revision for recipes that share
                    a common <filename>include</filename> file.
                    You can think of this variable as part of the recipe revision
                    as set from within an include file.</para>
                <para>Suppose, for example, you have a set of recipes that
                    are used across several projects.
                    And, within each of those recipes the revision
                    (its <link linkend='var-PR'><filename>PR</filename></link>
                    value) is set accordingly.
                    In this case, when the revision of those recipes changes,
                    the burden is on you to find all those recipes and
                    be sure that they get changed to reflect the updated
                    version of the recipe.
                    In this scenario, it can get complicated when recipes
                    that are used in many places and provide common functionality
                    are upgraded to a new revision.</para>
                <para>A more efficient way of dealing with this situation is
                    to set the <filename>INC_PR</filename> variable inside
                    the <filename>include</filename> files that the recipes
                    share and then expand the <filename>INC_PR</filename>
                    variable within the recipes to help
                    define the recipe revision.
                    </para>
                <para>
                    The following provides an example that shows how to use
                    the <filename>INC_PR</filename> variable
                    given a common <filename>include</filename> file that
                    defines the variable.
                    Once the variable is defined in the
                    <filename>include</filename> file, you can use the
                    variable to set the <filename>PR</filename> values in
                    each recipe.
                    You will notice that when you set a recipe's
                    <filename>PR</filename> you can provide more granular
                    revisioning by appending values to the
                    <filename>INC_PR</filename> variable:
                    <literallayout class='monospaced'>
recipes-graphics/xorg-font/xorg-font-common.inc:INC_PR = "r2"
recipes-graphics/xorg-font/encodings_1.0.4.bb:PR = "${INC_PR}.1"
recipes-graphics/xorg-font/font-util_1.3.0.bb:PR = "${INC_PR}.0"
recipes-graphics/xorg-font/font-alias_1.0.3.bb:PR = "${INC_PR}.3"
                    </literallayout>
                    The first line of the example establishes the baseline
                    revision to be used for all recipes that use the
                    <filename>include</filename> file.
                    The remaining lines in the example are from individual
                    recipes and show how the <filename>PR</filename> value
                    is set.</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-INHIBIT_PACKAGE_STRIP'><glossterm>INHIBIT_PACKAGE_STRIP</glossterm>
            <glossdef>
                <para>
                    If set to "1", causes the build to not strip binaries in resulting packages.
                </para>
            </glossdef>
        </glossentry>


        <glossentry id='var-INHERIT'><glossterm>INHERIT</glossterm>
            <glossdef>
                <para>
                    Causes the named class to be inherited at
                    this point during parsing.
                    The variable is only valid in configuration files.
                </para>
            </glossdef>
        </glossentry>


        <glossentry id='var-INITSCRIPT_PACKAGES'><glossterm>INITSCRIPT_PACKAGES</glossterm>
            <glossdef>
                <para>
                    A list of the packages that contain initscripts.
                    If multiple packages are specified, you need to append the package name
                    to the other <filename>INITSCRIPT_*</filename> as an override.</para>
                 <para>
                    This variable is used in recipes when using <filename>update-rc.d.bbclass</filename>.
                    The variable is optional and defaults to the
                    <link linkend='var-PN'><filename>PN</filename></link> variable.
                </para>
           </glossdef>
        </glossentry>

        <glossentry id='var-INITSCRIPT_NAME'><glossterm>INITSCRIPT_NAME</glossterm>
            <glossdef>
                <para>
                    The filename of the initscript as installed to <filename>${etcdir}/init.d</filename>.
                </para>
                <para>
                    This variable is used in recipes when using <filename>update-rc.d.bbclass</filename>.
                    The variable is Mandatory.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-INITSCRIPT_PARAMS'><glossterm>INITSCRIPT_PARAMS</glossterm>
            <glossdef>
                <para>
                    Specifies the options to pass to <filename>update-rc.d</filename>.
                    Here is an example:
                    <literallayout class='monospaced'>
     INITSCRIPT_PARAMS = "start 99 5 2 . stop 20 0 1 6 ."
                    </literallayout>
                    In this example, the script has a runlevel of 99,
                    starts the script in initlevels 2 and 5, and
                    stops the script in levels 0, 1 and 6.
                </para>
                <para>
                    The variable is mandatory and is used in recipes when using
                    <filename>update-rc.d.bbclass</filename>.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-INSANE_SKIP'><glossterm>INSANE_SKIP</glossterm>
            <glossdef>
                <para>
                    Specifies the QA checks to skip for a specific package
                    within a recipe.
                    For example, to skip the check for symbolic link
                    <filename>.so</filename> files in the main package of a
                    recipe, add the following to the recipe.
                    The package name override must be used, which in this
                    example is <filename>${PN}</filename>:
                    <literallayout class='monospaced'>
     INSANE_SKIP_${PN} += "dev-so"
                    </literallayout>
                </para>
                <para>
                    See the "<link linkend='ref-classes-insane'>Generated Output Quality Assurance Checks - <filename>insane.bbclass</filename></link>"
                    section for a list of the valid QA checks you can
                    specify using this variable.
                </para>
            </glossdef>
        </glossentry>


    </glossdiv>

<!--            <glossdiv id='var-glossary-j'><title>J</title>-->
<!--            </glossdiv>-->

   <glossdiv id='var-glossary-k'><title>K</title>

        <glossentry id='var-KARCH'><glossterm>KARCH</glossterm>
            <glossdef>
                <para>
                    Defines the kernel architecture used when assembling
                    the configuration.
                    Architectures supported for this release are:
                    <literallayout class='monospaced'>
     powerpc
     arm
     i386
     mips
     powerpc
     x86_64
                    </literallayout>
                </para>

                <para>
                    You define the <filename>KARCH</filename> variable in the
                    <ulink url='&YOCTO_DOCS_KERNEL_DEV_URL;#bsp-descriptions'>BSP Descriptions</ulink>.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-KBRANCH'><glossterm>KBRANCH</glossterm>
            <glossdef>
                <para>
                    A regular expression used by the build process to explicitly identify the kernel
                    branch that is validated, patched and configured during a build.
                    The <filename>KBRANCH</filename> variable is optional.
                    You can use it to trigger checks to ensure the exact kernel branch you want is
                    being used by the build process.
                </para>

                <para>
                    Values for this variable are set in the kernel's recipe file and the kernel's
                    append file.
                    For example, if you are using the Yocto Project kernel that is based on the
                    Linux 3.4 kernel, the kernel recipe file is the
                    <filename>meta/recipes-kernel/linux/linux-yocto_3.4.bb</filename> file.
                    Following is the default value for <filename>KBRANCH</filename> and the default
                    override for the architectures the Yocto Project supports:
                    <literallayout class='monospaced'>
     KBRANCH_DEFAULT = "standard/base"
     KBRANCH = "${KBRANCH_DEFAULT}"
                    </literallayout>
                    This branch exists in the <filename>linux-yocto-3.4</filename> kernel Git
                    repository <ulink url='&YOCTO_GIT_URL;/cgit.cgi/linux-yocto-3.4/refs/heads'></ulink>.
                </para>

                <para>
                    This variable is also used from the kernel's append file to identify the kernel
                    branch specific to a particular machine or target hardware.
                    The kernel's append file is located in the BSP layer for a given machine.
                    For example, the kernel append file for the Crown Bay BSP is in the
                    <filename>meta-intel</filename> Git repository and is named
                    <filename>meta-crownbay/recipes-kernel/linux/linux-yocto_3.4.bbappend</filename>.
                    Here are the related statements from the append file:
                    <literallayout class='monospaced'>
     COMPATIBLE_MACHINE_crownbay = "crownbay"
     KMACHINE_crownbay  = "crownbay"
     KBRANCH_crownbay  = "standard/crownbay"

     COMPATIBLE_MACHINE_crownbay-noemgd = "crownbay-noemgd"
     KMACHINE_crownbay-noemgd  = "crownbay"
     KBRANCH_crownbay-noemgd  = "standard/crownbay"
                    </literallayout>
                        The <filename>KBRANCH_*</filename> statements identify the kernel branch to
                        use when building for the Crown Bay BSP.
                        In this case there are two identical statements: one for each type of
                        Crown Bay machine.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-KBRANCH_DEFAULT'><glossterm>KBRANCH_DEFAULT</glossterm>
            <glossdef>
                <para>
                    Defines the Linux kernel source repository's default
                    branch used to build the Linux kernel.
                    The <filename>KBRANCH_DEFAULT</filename> value is
                    the default value for
                    <link linkend='var-KBRANCH'><filename>KBRANCH</filename></link>.
                    Unless you specify otherwise,
                    <filename>KBRANCH_DEFAULT</filename> initializes to
                    "master".
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-KERNEL_EXTRA_ARGS'><glossterm>KERNEL_EXTRA_ARGS</glossterm>
            <glossdef>
                <para>
                    Specifies additional <filename>make</filename>
                    command-line arguments the OpenEmbedded build system
                    passes on when compiling the kernel.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-KERNEL_FEATURES'><glossterm>KERNEL_FEATURES</glossterm>
            <glossdef>
                <para>Includes additional metadata from the Yocto Project kernel Git repository.
                    In the OpenEmbedded build system, the default Board Support Packages (BSPs)
                    <ulink url='&YOCTO_DOCS_DEV_URL;#metadata'>Metadata</ulink>
                    is provided through
                    the <link linkend='var-KMACHINE'><filename>KMACHINE</filename></link>
                    and <link linkend='var-KBRANCH'><filename>KBRANCH</filename></link> variables.
                    You can use the <filename>KERNEL_FEATURES</filename> variable to further
                    add metadata for all BSPs.</para>
                <para>The metadata you add through this variable includes config fragments and
                    features descriptions,
                    which usually includes patches as well as config fragments.
                    You typically override the <filename>KERNEL_FEATURES</filename> variable
                    for a specific machine.
                    In this way, you can provide validated, but optional, sets of kernel
                    configurations and features.</para>
                <para>For example, the following adds <filename>netfilter</filename> to all
                    the Yocto Project kernels and adds sound support to the <filename>qemux86</filename>
                    machine:
                    <literallayout class='monospaced'>
     # Add netfilter to all linux-yocto kernels
     KERNEL_FEATURES="features/netfilter"

     # Add sound support to the qemux86 machine
     KERNEL_FEATURES_append_qemux86=" cfg/sound"
                    </literallayout></para>
            </glossdef>
        </glossentry>

        <glossentry id='var-KERNEL_IMAGETYPE'><glossterm>KERNEL_IMAGETYPE</glossterm>
            <glossdef>
                <para>The type of kernel to build for a device, usually set by the
                    machine configuration files and defaults to "zImage".
                    This variable is used
                    when building the kernel and is passed to <filename>make</filename> as the target to
                    build.</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-KERNEL_PATH'><glossterm>KERNEL_PATH</glossterm>
            <glossdef>
                <para>
                    The location of the kernel sources.
                    This variable is set to the value of the
                    <link linkend='var-STAGING_KERNEL_DIR'><filename>STAGING_KERNEL_DIR</filename></link>
                    within the <filename>module.bbclass</filename> class.
                    For information on how this variable is used, see the
                    "<ulink url='&YOCTO_DOCS_KERNEL_DEV_URL;#incorporating-out-of-tree-modules'>Incorporating Out-of-Tree Modules</ulink>"
                    section.
                </para>

                <para>
                    The <link linkend='var-KERNEL_SRC'><filename>KERNEL_SRC</filename></link>
                    variable is identical to the <filename>KERNEL_PATH</filename>
                    variable.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-KERNEL_SRC'><glossterm>KERNEL_SRC</glossterm>
            <glossdef>
                <para>
                    The location of the kernel sources.
                    This variable is set to the value of the
                    <link linkend='var-STAGING_KERNEL_DIR'><filename>STAGING_KERNEL_DIR</filename></link>
                    within the <filename>module.bbclass</filename> class.
                    For information on how this variable is used, see the
                    "<ulink url='&YOCTO_DOCS_KERNEL_DEV_URL;#incorporating-out-of-tree-modules'>Incorporating Out-of-Tree Modules</ulink>"
                    section.
                </para>

                <para>
                    The <link linkend='var-KERNEL_PATH'><filename>KERNEL_PATH</filename></link>
                    variable is identical to the <filename>KERNEL_SRC</filename>
                    variable.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-KFEATURE_DESCRIPTION'><glossterm>KFEATURE_DESCRIPTION</glossterm>
            <glossdef>
                <para>
                    Provides a short description of a configuration fragment.
                    You use this variable in the <filename>.scc</filename>
                    file that describes a configuration fragment file.
                    Here is the variable used in a file named
                    <filename>smp.scc</filename> to describe SMP being
                    enabled:
                    <literallayout class='monospaced'>
     define KFEATURE_DESCRIPTION "Enable SMP"
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-KMACHINE'><glossterm>KMACHINE</glossterm>
            <glossdef>
                <para>
                    The machine as known by the kernel.
                    Sometimes the machine name used by the kernel does not match the machine name
                    used by the OpenEmbedded build system.
                    For example, the machine name that the OpenEmbedded build system understands as
                    <filename>qemuarm</filename> goes by a different name in the Linux Yocto kernel.
                    The kernel understands that machine as <filename>arm_versatile926ejs</filename>.
                    For cases like these, the <filename>KMACHINE</filename> variable maps the
                    kernel machine name to the OpenEmbedded build system machine name.
                </para>

                <para>
                    Kernel machine names are initially defined in the
                    Yocto Linux Kernel's <filename>meta</filename> branch.
                    From the <filename>meta</filename> branch, look in
                    the <filename>meta/cfg/kernel-cache/bsp/&lt;bsp_name&gt;/&lt;bsp-name&gt;-&lt;kernel-type&gt;.scc</filename> file.
                    For example, from the <filename>meta</filename> branch in the
                    <filename>linux-yocto-3.0</filename> kernel, the
                    <filename>meta/cfg/kernel-cache/bsp/cedartrail/cedartrail-standard.scc</filename> file
                    has the following:
                    <literallayout class='monospaced'>
     define KMACHINE cedartrail
     define KTYPE standard
     define KARCH i386

     include ktypes/standard
     branch cedartrail

     include cedartrail.scc
                    </literallayout>
                    You can see that the kernel understands the machine name for
                    the Cedar Trail Board Support Package (BSP) as
                    <filename>cedartrail</filename>.
                </para>

                <para>
                    If you look in the Cedar Trail BSP layer in the
                    <filename>meta-intel</filename>
                    <ulink url='&YOCTO_DOCS_DEV_URL;#source-repositories'>Source Repositories</ulink>
                    at <filename>meta-cedartrail/recipes-kernel/linux/linux-yocto_3.0.bbappend</filename>,
                    you will find the following statements among others:
                    <literallayout class='monospaced'>
     COMPATIBLE_MACHINE_cedartrail = "cedartrail"
     KMACHINE_cedartrail  = "cedartrail"
     KBRANCH_cedartrail  = "yocto/standard/cedartrail"
     KERNEL_FEATURES_append_cedartrail += "bsp/cedartrail/cedartrail-pvr-merge.scc"
     KERNEL_FEATURES_append_cedartrail += "cfg/efi-ext.scc"

     COMPATIBLE_MACHINE_cedartrail-nopvr = "cedartrail"
     KMACHINE_cedartrail-nopvr  = "cedartrail"
     KBRANCH_cedartrail-nopvr  = "yocto/standard/cedartrail"
     KERNEL_FEATURES_append_cedartrail-nopvr += " cfg/smp.scc"
                    </literallayout>
                    The <filename>KMACHINE</filename> statements in the kernel's append file make sure that
                    the OpenEmbedded build system and the Yocto Linux kernel understand the same machine
                    names.
                </para>

                <para>
                    This append file uses two <filename>KMACHINE</filename> statements.
                    The first is not really necessary but does ensure that the machine known to the
                    OpenEmbedded build system as <filename>cedartrail</filename> maps to the machine
                    in the kernel also known as <filename>cedartrail</filename>:
                    <literallayout class='monospaced'>
     KMACHINE_cedartrail  = "cedartrail"
                    </literallayout>
                </para>

                <para>
                    The second statement is a good example of why the <filename>KMACHINE</filename> variable
                    is needed.
                    In this example, the OpenEmbedded build system uses the <filename>cedartrail-nopvr</filename>
                    machine name to refer to the Cedar Trail BSP that does not support the proprietary
                    PowerVR driver.
                    The kernel, however, uses the machine name <filename>cedartrail</filename>.
                    Thus, the append file must map the <filename>cedartrail-nopvr</filename> machine name to
                    the kernel's <filename>cedartrail</filename> name:
                    <literallayout class='monospaced'>
     KMACHINE_cedartrail-nopvr  = "cedartrail"
                    </literallayout>
                </para>

                <para>
                    BSPs that ship with the Yocto Project release provide all mappings between the Yocto
                    Project kernel machine names and the OpenEmbedded machine names.
                    Be sure to use the <filename>KMACHINE</filename> if you create a BSP and the machine
                    name you use is different than that used in the kernel.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-KTYPE'><glossterm>KTYPE</glossterm>
            <glossdef>
                <para>
                    Defines the kernel type to be used in assembling the
                    configuration.
                    The linux-yocto recipes define "standard", "tiny",
                    and "preempt-rt" kernel types.
                    See the
                    "<ulink url='&YOCTO_DOCS_KERNEL_DEV_URL;#kernel-types'>Kernel Types</ulink>"
                    section in the Yocto Project Linux Kernel Development
                    Manual for more information on kernel types.
                </para>

                <para>
                    You define the <filename>KTYPE</filename> variable in the
                    <ulink url='&YOCTO_DOCS_KERNEL_DEV_URL;#bsp-descriptions'>BSP Descriptions</ulink>.
                    The value you use must match the value used for the
                    <link linkend='var-LINUX_KERNEL_TYPE'><filename>LINUX_KERNEL_TYPE</filename></link>
                    value used by the kernel recipe.
                </para>
            </glossdef>
        </glossentry>
   </glossdiv>

    <glossdiv id='var-glossary-l'><title>L</title>

        <glossentry id='var-LAYERDEPENDS'><glossterm>LAYERDEPENDS</glossterm>
            <glossdef>
                <para>Lists the layers that this recipe depends upon, separated by spaces.
                    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).
                    An error will be produced if any dependency is missing or
                    the version numbers do not match exactly (if specified).
                    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>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-LAYERVERSION'><glossterm>LAYERVERSION</glossterm>
            <glossdef>
                <para>Optionally specifies the version of a layer as a single number.
                    You can use this within
                    <link linkend='var-LAYERDEPENDS'><filename>LAYERDEPENDS</filename></link>
                    for another layer in order to depend on a specific version
                    of the 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>LAYERVERSION_mylayer</filename>).</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-LIC_FILES_CHKSUM'><glossterm>LIC_FILES_CHKSUM</glossterm>
            <glossdef>
                <para>Checksums of the license text in the recipe source code.</para>
                <para>This variable tracks changes in license text of the source
                    code files.
                    If the license text is changed, it will trigger a build
                    failure, which gives the developer an opportunity to review any
                    license change.</para>
                <para>
                    This variable must be defined for all recipes (unless
                    <link linkend='var-LICENSE'><filename>LICENSE</filename></link>
                    is set to "CLOSED")</para>
                <para>For more information, see the
                    <link linkend='usingpoky-configuring-LIC_FILES_CHKSUM'>
                    Tracking License Changes</link> section</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-LICENSE'><glossterm>LICENSE</glossterm>
            <glossdef>
                <para>
                    The list of source licenses for the recipe.
                    Follow these rules:
                    <itemizedlist>
                        <listitem><para>Do not use spaces within individual
                            license names.</para></listitem>
                        <listitem><para>Separate license names using
                            | (pipe) when there is a choice between licenses.
                            </para></listitem>
                        <listitem><para>Separate license names using
                            &amp; (ampersand) when multiple licenses exist
                            that cover different parts of the source.
                            </para></listitem>
                        <listitem><para>You can use spaces between license
                            names.</para></listitem>
                    </itemizedlist>
                </para>

                <para>
                    Here are some examples:
                    <literallayout class='monospaced'>
     LICENSE = "LGPLv2.1 | GPLv3"
     LICENSE = "MPL-1 &amp; LGPLv2.1"
     LICENSE = "GPLv2+"
                    </literallayout>
                    The first example is from the recipes for Qt, which the user
                    may choose to distribute under either the LGPL version
                    2.1 or GPL version 3.
                    The second example is from Cairo where two licenses cover
                    different parts of the source code.
                    The final example is from <filename>sysstat</filename>,
                    which presents a single license.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-LICENSE_PATH'><glossterm>LICENSE_PATH</glossterm>
            <glossdef>
                <para>Path to additional licenses used during the build.
                    By default, the OpenEmbedded build system uses <filename>COMMON_LICENSE_DIR</filename>
                    to define the directory that holds common license text used during the build.
                    The <filename>LICENSE_PATH</filename> variable allows you to extend that
                    location to other areas that have additional licenses:
                    <literallayout class='monospaced'>
     LICENSE_PATH += "/path/to/additional/common/licenses"
                    </literallayout></para>
            </glossdef>
        </glossentry>

        <glossentry id='var-LINUX_KERNEL_TYPE'><glossterm>LINUX_KERNEL_TYPE</glossterm>
            <glossdef>
                <para>
                    Defines the kernel type to be used in assembling the
                    configuration.
                    The linux-yocto recipes define "standard", "tiny", and
                    "preempt-rt" kernel types.
                    See the
                    "<ulink url='&YOCTO_DOCS_KERNEL_DEV_URL;#kernel-types'>Kernel Types</ulink>"
                    section in the Yocto Project Linux Kernel Development
                    Manual for more information on kernel types.
                </para>

                <para>
                    If you do not specify a
                    <filename>LINUX_KERNEL_TYPE</filename>, it defaults to
                    "standard".
                    Together with
                    <link linkend='var-KMACHINE'><filename>KMACHINE</filename></link>,
                    the <filename>LINUX_KERNEL_TYPE</filename> variable
                    defines the search
                    arguments used by the kernel tools to find the appropriate
                    description within the kernel
                    <ulink url='&YOCTO_DOCS_DEV_URL;#metadata'>Metadata</ulink>
                    with which to build out the sources and configuration.
                    </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-LINUX_VERSION'><glossterm>LINUX_VERSION</glossterm>
            <glossdef>
                <para>The Linux version from <filename>kernel.org</filename>
                    on which the Linux kernel image being built using the
                    OpenEmbedded build system is based.
                    You define this variable in the kernel recipe.
                    For example, the <filename>linux-yocto-3.4.bb</filename>
                    kernel recipe found in
                    <filename>meta/recipes-kernel/linux</filename>
                    defines the variables as follows:
                    <literallayout class='monospaced'>
     LINUX_VERSION ?= "3.4.24"
                    </literallayout>
                    The <filename>LINUX_VERSION</filename> variable is used to
                    define <link linkend='var-PV'><filename>PV</filename></link>
                    for the recipe:
                    <literallayout class='monospaced'>
     PV = "${LINUX_VERSION}+git${SRCPV}"
                    </literallayout></para>
            </glossdef>
        </glossentry>

        <glossentry id='var-LINUX_VERSION_EXTENSION'><glossterm>LINUX_VERSION_EXTENSION</glossterm>
            <glossdef>
                <para>A string extension compiled into the version
                    string of the Linux kernel built with the OpenEmbedded
                    build system.
                    You define this variable in the kernel recipe.
                    For example, the linux-yocto kernel recipes all define
                    the variable as follows:
                    <literallayout class='monospaced'>
     LINUX_VERSION_EXTENSION ?= "-yocto-${<link linkend='var-LINUX_KERNEL_TYPE'>LINUX_KERNEL_TYPE</link>}"
                    </literallayout>
                    Defining this variable essentially sets the
                    Linux kernel configuration item
                    <filename>CONFIG_LOCALVERSION</filename>, which is visible
                    through the <filename>uname</filename> command.
                    Here is an example that shows the extension assuming it
                    was set as previously shown:
                    <literallayout class='monospaced'>
     $ uname -r
     3.7.0-rc8-custom
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-LOG_DIR'><glossterm>LOG_DIR</glossterm>
            <glossdef>
                <para>
                    Specifies the directory to which the OpenEmbedded build
                    system writes overall log files.
                    The default directory is <filename>${TMPDIR}/log</filename>.
                </para>
                <para>
                    For the directory containing logs specific to each task,
                    see the <link linkend='var-T'><filename>T</filename></link>
                    variable.
                </para>
            </glossdef>
        </glossentry>

    </glossdiv>

    <glossdiv id='var-glossary-m'><title>M</title>

         <glossentry id='var-MACHINE'><glossterm>MACHINE</glossterm>
            <glossdef>
                <para>
                    Specifies the target device for which the image is built.
                    You define <filename>MACHINE</filename> in the
                    <filename>local.conf</filename> file found in the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>Build Directory</ulink>.
                    By default, <filename>MACHINE</filename> is set to
                    "qemux86", which is an x86-based architecture machine to
                    be emulated using QEMU:
                    <literallayout class='monospaced'>
     MACHINE ?= "qemux86"
                    </literallayout>
                    The variable corresponds to a machine configuration file of the
                    same name, through which machine-specific configurations are set.
                    Thus, when <filename>MACHINE</filename> is set to "qemux86" there
                    exists the corresponding <filename>qemux86.conf</filename> machine
                    configuration file, which can be found in the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#source-directory'>Source Directory</ulink>
                    in <filename>meta/conf/machine</filename>.
                </para>

                <para>
                    The list of machines supported by the Yocto Project as
                    shipped include the following:
                    <literallayout class='monospaced'>
     MACHINE ?= "qemuarm"
     MACHINE ?= "qemumips"
     MACHINE ?= "qemuppc"
     MACHINE ?= "qemux86"
     MACHINE ?= "qemux86-64"
     MACHINE ?= "atom-pc"
     MACHINE ?= "beagleboard"
     MACHINE ?= "mpc8315e-rdb"
     MACHINE ?= "routerstationpro"
                    </literallayout>
                    The last four are Yocto Project reference hardware boards, which
                    are provided in the <filename>meta-yocto-bsp</filename> layer.
                    <note>Adding additional Board Support Package (BSP) layers
                        to your configuration adds new possible settings for
                        <filename>MACHINE</filename>.
                    </note>
                </para>
            </glossdef>
         </glossentry>

         <glossentry id='var-MACHINE_ESSENTIAL_EXTRA_RDEPENDS'><glossterm>MACHINE_ESSENTIAL_EXTRA_RDEPENDS</glossterm>
            <glossdef>
                <para></para>
                <para>
                    A list of required machine-specific packages to install as part of
                    the image being built.
                    The build process depends on these packages being present.
                    Furthermore, because this is a "machine essential" variable, the list of
                    packages are essential for the machine to boot.
                    The impact of this variable affects images based on
                    <filename>packagegroup-core-boot</filename>,
                    including the <filename>core-image-minimal</filename> image.
                </para>
                <para>
                    This variable is similar to the
                    <filename><link linkend='var-MACHINE_ESSENTIAL_EXTRA_RRECOMMENDS'>MACHINE_ESSENTIAL_EXTRA_RRECOMMENDS</link></filename>
                    variable with the exception that the image being built has a build
                    dependency on the variable's list of packages.
                    In other words, the image will not build if a file in this list is not found.
                </para>
                <para>
                    As an example, suppose the machine for which you are building requires
                    <filename>example-init</filename> to be run during boot to initialize the hardware.
                    In this case, you would use the following in the machine's
                    <filename>.conf</filename> configuration file:
                    <literallayout class='monospaced'>
     MACHINE_ESSENTIAL_EXTRA_RDEPENDS += "example-init"
                    </literallayout>
                </para>
            </glossdef>
         </glossentry>

         <glossentry id='var-MACHINE_ESSENTIAL_EXTRA_RRECOMMENDS'><glossterm>MACHINE_ESSENTIAL_EXTRA_RRECOMMENDS</glossterm>
            <glossdef>
                <para></para>
                <para>
                    A list of recommended machine-specific packages to install as part of
                    the image being built.
                    The build process does not depend on these packages being present.
                    However, because this is a "machine essential" variable, the list of
                    packages are essential for the machine to boot.
                    The impact of this variable affects images based on
                    <filename>packagegroup-core-boot</filename>,
                    including the <filename>core-image-minimal</filename> image.
                </para>
                <para>
                    This variable is similar to the
                    <filename><link linkend='var-MACHINE_ESSENTIAL_EXTRA_RDEPENDS'>MACHINE_ESSENTIAL_EXTRA_RDEPENDS</link></filename>
                    variable with the exception that the image being built does not have a build
                    dependency on the variable's list of packages.
                    In other words, the image will still build if a package in this list is not found.
                    Typically, this variable is used to handle essential kernel modules, whose
                    functionality may be selected to be built into the kernel rather than as a module,
                    in which case a package will not be produced.
                </para>
                <para>
                    Consider an example where you have a custom kernel where a specific touchscreen
                    driver is required for the machine to be usable.
                    However, the driver can be built as a module or
                    into the kernel depending on the kernel configuration.
                    If the driver is built as a module, you want it to be installed.
                    But, when the driver is built into the kernel, you still want the
                    build to succeed.
                    This variable sets up a "recommends" relationship so that in the latter case,
                    the build will not fail due to the missing package.
                    To accomplish this, assuming the package for the module was called
                    <filename>kernel-module-ab123</filename>, you would use the
                    following in the machine's <filename>.conf</filename> configuration
                    file:
                    <literallayout class='monospaced'>
     MACHINE_ESSENTIAL_EXTRA_RRECOMMENDS += "kernel-module-ab123"
                    </literallayout>
                </para>
                <para>
                    Some examples of these machine essentials are flash, screen, keyboard, mouse,
                    or touchscreen drivers (depending on the machine).
                </para>
            </glossdef>
        </glossentry>

         <glossentry id='var-MACHINE_EXTRA_RDEPENDS'><glossterm>MACHINE_EXTRA_RDEPENDS</glossterm>
            <glossdef>
                <para>
                    A list of machine-specific packages to install as part of the
                    image being built that are not essential for the machine to boot.
                    However, the build process for more fully-featured images
                    depends on the packages being present.
                </para>
                <para>
                    This variable affects all images based on
                    <filename>packagegroup-base</filename>, which does not include the
                    <filename>core-image-minimal</filename> or <filename>core-image-basic</filename>
                    images.
                </para>
                <para>
                    The variable is similar to the
                    <filename><link linkend='var-MACHINE_EXTRA_RRECOMMENDS'>MACHINE_EXTRA_RRECOMMENDS</link></filename>
                    variable with the exception that the image being built has a build
                    dependency on the variable's list of packages.
                    In other words, the image will not build if a file in this list is not found.
                </para>
                <para>
                    An example is a machine that has WiFi capability but is not
                    essential for the machine to boot the image.
                    However, if you are building a more fully-featured image, you want to enable
                    the WiFi.
                    The package containing the firmware for the WiFi hardware is always
                    expected to exist, so it is acceptable for the build process to depend upon
                    finding the package.
                    In this case, assuming the package for the firmware was called
                    <filename>wifidriver-firmware</filename>, you would use the following in the
                    <filename>.conf</filename> file for the machine:
                    <literallayout class='monospaced'>
     MACHINE_EXTRA_RDEPENDS += "wifidriver-firmware"
                    </literallayout>
                </para>
            </glossdef>
         </glossentry>

         <glossentry id='var-MACHINE_EXTRA_RRECOMMENDS'><glossterm>MACHINE_EXTRA_RRECOMMENDS</glossterm>
            <glossdef>
                <para></para>
                <para>
                    A list of machine-specific packages to install as part of the
                    image being built that are not essential for booting the machine.
                    The image being built has no build dependency on this list of packages.
                </para>
                <para>
                    This variable affects only images based on
                    <filename>packagegroup-base</filename>, which does not include the
                    <filename>core-image-minimal</filename> or <filename>core-image-basic</filename>
                    images.
                </para>
                <para>
                    This variable is similar to the
                    <filename><link linkend='var-MACHINE_EXTRA_RDEPENDS'>MACHINE_EXTRA_RDEPENDS</link></filename>
                    variable with the exception that the image being built does not have a build
                    dependency on the variable's list of packages.
                    In other words, the image will build if a file in this list is not found.
                </para>
                <para>
                    An example is a machine that has WiFi capability but is not essential
                    For the machine to boot the image.
                    However, if you are building a more fully-featured image, you want to enable
                    WiFi.
                    In this case, the package containing the WiFi kernel module will not be produced
                    if the WiFi driver is built into the kernel, in which case you still want the
                    build to succeed instead of failing as a result of the package not being found.
                    To accomplish this, assuming the package for the module was called
                    <filename>kernel-module-examplewifi</filename>, you would use the
                    following in the <filename>.conf</filename> file for the machine:
                    <literallayout class='monospaced'>
     MACHINE_EXTRA_RRECOMMENDS += "kernel-module-examplewifi"
                    </literallayout>
                </para>
            </glossdef>
         </glossentry>

         <glossentry id='var-MACHINE_FEATURES'><glossterm>MACHINE_FEATURES</glossterm>
            <glossdef>
                <para>Specifies the list of hardware features the
                    <link linkend='var-MACHINE'>MACHINE</link> supports.
                    For example, including the "bluetooth" feature causes the
                    <filename>bluez</filename> bluetooth daemon to be built and
                    added to the image.
                    It also causes the <filename>connman</filename> recipe
                    to look at <filename>MACHINE_FEATURES</filename> and when it
                    finds "bluetooth" there it enables the bluetooth
                    support in ConnMan.
                </para>

                <para>
                    For a list of features supported by the Yocto Project as shipped,
                    see the "<link linkend='ref-features-machine'>Machine</link>" section.
                </para>
            </glossdef>
         </glossentry>

        <glossentry id='var-MACHINE_FEATURES_BACKFILL'><glossterm>MACHINE_FEATURES_BACKFILL</glossterm>
            <glossdef>
                <para>Features to be added to
                    <filename><link linkend='var-MACHINE_FEATURES'>MACHINE_FEATURES</link></filename>
                    if not also present in
                    <filename><link linkend='var-MACHINE_FEATURES_BACKFILL_CONSIDERED'>MACHINE_FEATURES_BACKFILL_CONSIDERED</link></filename>.
                </para>

                <para>
                    This variable is set in the <filename>meta/conf/bitbake.conf</filename> file.
                    It is not intended to be user-configurable.
                    It is best to just reference the variable to see which machine features are
                    being backfilled for all machine configurations.
                    See the "<link linkend='ref-features-backfill'>Feature backfilling</link>" section for
                    more information.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-MACHINE_FEATURES_BACKFILL_CONSIDERED'><glossterm>MACHINE_FEATURES_BACKFILL_CONSIDERED</glossterm>
            <glossdef>
                <para>Features from
                    <filename><link linkend='var-MACHINE_FEATURES_BACKFILL'>MACHINE_FEATURES_BACKFILL</link></filename>
                    that should not be backfilled (i.e. added to
                    <filename><link linkend='var-MACHINE_FEATURES'>MACHINE_FEATURES</link></filename>)
                    during the build.
                    See the "<link linkend='ref-features-backfill'>Feature backfilling</link>" section for
                    more information.
                    </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-MACHINEOVERRIDES'><glossterm>MACHINEOVERRIDES</glossterm>
            <glossdef>
                <para>
                    Lists overrides specific to the current machine.
                    By default, this list includes the value
                    of <filename><link linkend='var-MACHINE'>MACHINE</link></filename>.
                    You can extend the list to apply variable overrides for
                    classes of machines.
                    For example, all QEMU emulated machines (e.g. qemuarm,
                    qemux86, and so forth) include a common file named
                    <filename>meta/conf/machine/include/qemu.inc</filename>
                    that prepends <filename>MACHINEOVERRIDES</filename> with
                    the following variable override:
                    <literallayout class='monospaced'>
    MACHINEOVERRIDES =. "qemuall:"
                    </literallayout>
                    Applying an override like <filename>qemuall</filename>
                    affects all QEMU emulated machines elsewhere.
                    Here is an example from the
                    <filename>connman-conf</filename> recipe:
                    <literallayout class='monospaced'>
    SRC_URI_append_qemuall = "file://wired.config \
                              file://wired-setup \
                             "
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-MAINTAINER'><glossterm>MAINTAINER</glossterm>
            <glossdef>
                <para>The email address of the distribution maintainer.</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-MIRRORS'><glossterm>MIRRORS</glossterm>
            <glossdef>
                <para>
                    Specifies additional paths from which the OpenEmbedded
                    build system 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>

                <para>
                    Assuming your distribution
                    (<link linkend='var-DISTRO'><filename>DISTRO</filename></link>)
                    is "poky", the default value for
                    <filename>MIRRORS</filename> is defined in the
                    <filename>conf/distro/poky.conf</filename> file in the
                    <filename>meta-yocto</filename> Git repository.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-MLPREFIX'><glossterm>MLPREFIX</glossterm>
            <glossdef>
                <para>
                    Specifies a prefix has been added to
                    <link linkend='var-PN'><filename>PN</filename></link> to create a special version
                    of a recipe or package, such as a Multilib version.
                    The variable is used in places where the prefix needs to be
                    added to or removed from a the name (e.g. the
                    <link linkend='var-BPN'><filename>BPN</filename></link> variable).
                    <filename>MLPREFIX</filename> gets set when a prefix has been
                    added to <filename>PN</filename>.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-MODULE_TARBALL_DEPLOY'><glossterm>MODULE_TARBALL_DEPLOY</glossterm>
            <glossdef>
                <para>
                    Controls creation of the <filename>modules-*.tgz</filename>
                    file.
                    Set this variable to "0" to disable creation of this
                    file, which contains all of the kernel modules resulting
                    from a kernel build.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-MULTIMACH_TARGET_SYS'><glossterm>MULTIMACH_TARGET_SYS</glossterm>
            <glossdef>
                <para>
                    Separates files for different machines such that you can build
                    for multiple target machines using the same output directories.
                    See the <link linkend='var-STAMP'><filename>STAMP</filename></link> variable
                    for an example.
                </para>
            </glossdef>
        </glossentry>

    </glossdiv>

    <glossdiv id='var-glossary-n'><title>N</title>

        <glossentry id='var-NATIVELSBSTRING'><glossterm>NATIVELSBSTRING</glossterm>
            <glossdef>
                <para>
                    A string identifying the host distribution.
                    Strings consist of the host distributor ID
                    followed by the release, as reported by the
                    <filename>lsb_release</filename> tool
                    or as read from <filename>/etc/lsb-release</filename>.
                    For example, when running a build on Ubuntu 12.10, the value
                    is "Ubuntu-12.10".
                    If this information is unable to be determined, the value
                    resolves to "Unknown".
                </para>
                <para>
                    This variable is used by default to isolate native shared
                    state packages for different distributions (e.g. to avoid
                    problems with <filename>glibc</filename> version
                    incompatibilities).
                    Additionally, the variable is checked against
                    <link linkend='var-SANITY_TESTED_DISTROS'><filename>SANITY_TESTED_DISTROS</filename></link>
                    if that variable is set.
                </para>
            </glossdef>
        </glossentry>

    </glossdiv>

    <glossdiv id='var-glossary-o'><title>O</title>

        <glossentry id='var-OE_TERMINAL'><glossterm>OE_TERMINAL</glossterm>
            <glossdef>
                <para>
                    Controls how the OpenEmbedded build system spawns
                    interactive terminals on the host development system
                    (e.g. using the BitBake command with the
                    <filename>-c devshell</filename> command-line option).
                    For more information, see the
                    "<ulink url='&YOCTO_DOCS_DEV_URL;#platdev-appdev-devshell'>Using a Development Shell</ulink>" section
                    in the Yocto Project Development Manual.
                 </para>

                 <para>
                    You can use the following values for the
                    <filename>OE_TERMINAL</filename> variable:
                    <literallayout class='monospaced'>
     auto
     gnome
     xfce
     rxvt
     screen
     konsole
     none
                    </literallayout>
                    <note>Konsole support only works for KDE 3.x.
                        Also, "auto" is the default behavior for
                        <filename>OE_TERMINAL</filename></note>
                </para>
            </glossdef>
        </glossentry>

        <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.
                    You can find more information on how overrides are handled
                    in the BitBake Manual that is located at
                    <filename>bitbake/doc/manual</filename> in the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#source-directory'>Source Directory</ulink>.
                </para>
            </glossdef>
        </glossentry>
    </glossdiv>

    <glossdiv id='var-glossary-p'><title>P</title>

        <glossentry id='var-P'><glossterm>P</glossterm>
            <glossdef>
                <para>The recipe name and version.
                    <filename>P</filename> is comprised of the following:
                    <literallayout class='monospaced'>
     ${PN}-${PV}
                    </literallayout></para>
            </glossdef>
        </glossentry>

        <glossentry id='var-PACKAGE_ARCH'><glossterm>PACKAGE_ARCH</glossterm>
            <glossdef>
                <para>The architecture of the resulting package or packages.</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-PACKAGE_BEFORE_PN'><glossterm>PACKAGE_BEFORE_PN</glossterm>
            <glossdef>
                <para>Enables easily adding packages to
                <filename><link linkend='var-PACKAGES'>PACKAGES</link></filename>
                before <filename>${<link linkend='var-PN'>PN</link>}</filename>
                so that the packages can pick up files that would normally be
                included in the default package.</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-PACKAGE_CLASSES'><glossterm>PACKAGE_CLASSES</glossterm>
            <glossdef>
                <para>This variable, which is set in the <filename>local.conf</filename> configuration
                    file found in the <filename>conf</filename> folder of the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#source-directory'>Source Directory</ulink>,
                    specifies the package manager to use when packaging data.
                    You can provide one or more arguments for the variable with the first
                    argument being the package manager used to create images:
                    <literallayout class='monospaced'>
     PACKAGE_CLASSES ?= "package_rpm package_deb package_ipk"
                    </literallayout>
                    For information on build performance effects as a result of the
                    package manager use, see
                    <link linkend='ref-classes-package'>Packaging - <filename>package*.bbclass</filename></link>
                    in this manual.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-PACKAGE_EXTRA_ARCHS'><glossterm>PACKAGE_EXTRA_ARCHS</glossterm>
            <glossdef>
                <para>Specifies the list of architectures compatible with the device CPU.
                    This variable is useful when you build for several different devices that use
                    miscellaneous processors such as XScale and ARM926-EJS).</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-PACKAGECONFIG'><glossterm>PACKAGECONFIG</glossterm>
            <glossdef>
                <para>
                    This variable provides a means of enabling or disabling
                    features of a recipe on a per-recipe basis.
                    The <filename>PACKAGECONFIG</filename>
                    variable itself specifies a space-separated list of the
                    features to enable.
                    The features themselves are specified as flags on the
                    <filename>PACKAGECONFIG</filename> variable.
                    You can provide up to four arguments, which are separated by
                    commas, to determine the behavior of each feature
                    when it is enabled or disabled.
                    You can omit any argument you like but must retain the
                    separating commas.
                    The arguments specify the following:
                    <orderedlist>
                        <listitem><para>Extra arguments
                            that should be added to the configure script argument list
                            (<link linkend='var-EXTRA_OECONF'><filename>EXTRA_OECONF</filename></link>)
                            if the feature is enabled.</para></listitem>
                        <listitem><para>Extra arguments
                            that should be added to <filename>EXTRA_OECONF</filename>
                            if the feature is disabled.
                            </para></listitem>
                        <listitem><para>Additional build dependencies
                            (<link linkend='var-DEPENDS'><filename>DEPENDS</filename></link>)
                            that should be added if the feature is enabled.
                            </para></listitem>
                        <listitem><para>Additional runtime dependencies
                            (<link linkend='var-RDEPENDS'><filename>RDEPENDS</filename></link>)
                            that should be added if the feature is enabled.
                            </para></listitem>
                    </orderedlist>
                </para>

                <para>
                    Consider the following example taken from the
                    <filename>librsvg</filename> recipe.
                    In this example the feature is <filename>croco</filename>, which
                    has three arguments that determine the feature's behavior.
                        <literallayout class='monospaced'>
     PACKAGECONFIG ??= "croco"
     PACKAGECONFIG[croco] = "--with-croco,--without-croco,libcroco"
                        </literallayout>
                    The <filename>--with-croco</filename> and
                    <filename>libcroco</filename> arguments apply only if
                    the feature is enabled.
                    In this case, <filename>--with-croco</filename> is
                    added to the configure script argument list and
                    <filename>libcroco</filename> is added to
                    <filename><link linkend='var-DEPENDS'>DEPENDS</link></filename>.
                    On the other hand, if the feature is disabled say through
                    a <filename>.bbappend</filename> file in another layer, then
                    the second argument <filename>--without-croco</filename> is
                    added to the configure script rather than
                    <filename>--with-croco</filename>.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-PACKAGES'><glossterm>PACKAGES</glossterm>
            <glossdef>
                <para>The list of packages to be created from the recipe.
                    The default value is the following:
                    <literallayout class='monospaced'>
     ${PN}-dbg ${PN}-staticdev ${PN}-dev ${PN}-doc ${PN}-locale ${PACKAGE_BEFORE_PN} ${PN}
                    </literallayout></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
                    at build time 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.
                    Thus, if you attempt to include that package in an image,
                    you will get a dependency failure from the packaging system
                    during <filename>do_rootfs</filename>.
                </para>
                <para>
                    Typically, if there is a chance that such a situation can
                    occur and the package that is not created is valid
                    without the dependency being satisfied, then you should use
                    <link linkend='var-RRECOMMENDS'><filename>RRECOMMENDS</filename></link>
                    (a soft runtime dependency) instead of
                    <filename>RDEPENDS</filename>.
                </para>

                <para>
                    For an example of how to use the <filename>PACKAGES_DYNAMIC</filename>
                    variable when you are splitting packages, see the
                    "<ulink url='&YOCTO_DOCS_DEV_URL;#handling-optional-module-packaging'>Handling Optional Module Packaging</ulink>" section
                    in the Yocto Project Development Manual.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-PARALLEL_MAKE'><glossterm>PARALLEL_MAKE</glossterm>
            <glossdef>
                <para>Specifies extra options that are passed to the <filename>make</filename> command during the
                    compile tasks.
                    This variable is usually in the form <filename>-j 4</filename>, where the number
                    represents the maximum number of parallel threads make can run.
                    If you development host supports multiple cores a good rule of thumb is to set
                    this variable to twice the number of cores on the host.</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>).
                    This variable is comprised of the following:
                    <literallayout class='monospaced'>
     ${<link linkend='var-PN'>PN</link>}-${<link linkend='var-EXTENDPE'>EXTENDPE</link>}${<link linkend='var-PV'>PV</link>}-${<link linkend='var-PR'>PR</link>}
                    </literallayout></para>
            </glossdef>
        </glossentry>

        <glossentry id='var-PN'><glossterm>PN</glossterm>
            <glossdef>
                <para>This variable can have two separate functions depending on the context: a recipe
                    name or a resulting package name.</para>
                <para><filename>PN</filename> refers to a recipe name in the context of a file used
                    by the OpenEmbedded build system as input to create a package.
                    The name is normally extracted from the recipe file name.
                    For example, if the recipe is named
                    <filename>expat_2.0.1.bb</filename>, then the default value of <filename>PN</filename>
                    will be "expat".</para>
                <para>
                    The variable refers to a package name in the context of a file created or produced by the
                    OpenEmbedded build system.</para>
                <para>If applicable, the <filename>PN</filename> variable also contains any special
                    suffix or prefix.
                    For example, using <filename>bash</filename> to build packages for the native
                    machine, <filename>PN</filename> is <filename>bash-native</filename>.
                    Using <filename>bash</filename> to build packages for the target and for Multilib,
                    <filename>PN</filename> would be <filename>bash</filename> and
                    <filename>lib64-bash</filename>, respectively.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-PR'><glossterm>PR</glossterm>
            <glossdef>
                <para>The revision of the recipe.
                    The default value for this variable is "r0".
                    </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-PREMIRRORS'><glossterm>PREMIRRORS</glossterm>
            <glossdef>
                <para>
                    Specifies additional paths from which the OpenEmbedded
                    build system 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>
                    Assuming your distribution
                    (<link linkend='var-DISTRO'><filename>DISTRO</filename></link>)
                    is "poky", the default value for
                    <filename>PREMIRRORS</filename> is defined in the
                    <filename>conf/distro/poky.conf</filename> file in the
                    <filename>meta-yocto</filename> Git repository.
                </para>

                <para>
                    Typically, you could add a specific server for the
                    build system to attempt before any others by adding
                    something like the following to the
                    <filename>local.conf</filename> configuration file in the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>Build Directory</ulink>:
                    <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-PRINC'><glossterm>PRINC</glossterm>
            <glossdef>
                <para>Causes the <link linkend='var-PR'><filename>PR</filename></link>
                    variable of <filename>.bbappend</filename> files to
                    dynamically increment.
                    This increment minimizes the impact of layer ordering.</para>
                <para>In order to ensure multiple <filename>.bbappend</filename> files can co-exist,
                    <filename>PRINC</filename> should be self referencing.
                    This variable defaults to 0.</para>
                <para>Following is an example that increments <filename>PR</filename> by two:
                    <literallayout class='monospaced'>
     PRINC := "${@int(PRINC) + 2}"
                    </literallayout>
                    It is advisable not to use strings such as ".= '.1'" with the variable because
                    this usage is very sensitive to layer ordering.
                    You should avoid explicit assignments as they cannot
                    adequately represent multiple
                    <filename>.bbappend</filename> files.</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-PROVIDES'><glossterm>PROVIDES</glossterm>
            <glossdef>
                <para>
                    A list of aliases that a recipe also provides.
                    These aliases are useful for satisfying dependencies of
                    other recipes during the build (as specified by
                    <filename><link linkend='var-DEPENDS'>DEPENDS</link></filename>).
                    <note>
                        A recipe's own
                        <filename><link linkend='var-PN'>PN</link></filename>
                        is implicitly already in its
                        <filename>PROVIDES</filename> list.
                    </note>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-PV'><glossterm>PV</glossterm>
            <glossdef>
                <para>The version of the recipe.
                    The version is normally extracted from the recipe filename.
                    For example, if the recipe is named
                    <filename>expat_2.0.1.bb</filename>, then the default value of <filename>PV</filename>
                    will be "2.0.1".
                    <filename>PV</filename> is generally not overridden within
                    a recipe unless it is building an unstable (i.e. development) version from a source code repository
                    (e.g. Git or Subversion).
                 </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-PE'><glossterm>PE</glossterm>
            <glossdef>
                <para>
                    the epoch of the recipe.
                    The default value is "0".
                    The field is used to make upgrades possible when the versioning scheme changes in
                    some backwards incompatible way.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-PREFERRED_PROVIDER'><glossterm>PREFERRED_PROVIDER</glossterm>
            <glossdef>
                <para>
                    If multiple recipes provide an item, this variable
                    determines which recipe should be given preference.
                    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.
                    Here is an example:
                    <literallayout class='monospaced'>
     PREFERRED_PROVIDER_virtual/xserver = "xserver-xf86"
                    </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 to the
                    <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 number that could
                    potentially change.
                    Here are two examples:
                    <literallayout class='monospaced'>
     PREFERRED_VERSION_python = "2.6.6"
     PREFERRED_VERSION_linux-yocto = "3.0+git%"
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

    </glossdiv>

<!--            <glossdiv id='var-glossary-q'><title>Q</title>-->
<!--            </glossdiv>-->

    <glossdiv id='var-glossary-r'><title>R</title>

        <glossentry id='var-RCONFLICTS'><glossterm>RCONFLICTS</glossterm>
            <glossdef>
                <para>The list of packages that conflict with another package.
                    Note that the package will not be installed if the conflicting packages are not
                    first removed.</para>
                <para>
                   Like all package-controlling variables, you must always use them in
                   conjunction with a package name override.
                   Here is an example:
                   <literallayout class='monospaced'>
     RCONFLICTS_${PN} = "another-conflicting-package-name"
                   </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-RDEPENDS'><glossterm>RDEPENDS</glossterm>
            <glossdef>
                <para>
                    Lists a package's run-time dependencies (i.e. other packages)
                    that must be installed for the package to be built.
                    In other words, in order for the package to be built and
                    run correctly, it depends on the listed packages.
                    If a package in this list cannot be found, it is probable
                    that a dependency error would occur before the build.
                </para>

                <para>
                    The names of the variables you list with
                    <filename>RDEPENDS</filename> must be the names of other
                    packages as listed in the
                    <link linkend='var-PACKAGES'><filename>PACKAGES</filename></link>
                    variable.
                    You should not list recipe names
                    (<link linkend='var-PN'><filename>PN</filename></link>).
                </para>

                <para>
                    Because the <filename>RDEPENDS</filename> variable applies
                    to packages being built, you should
                    always attach a package name to the variable to specify the
                    particular run-time package that has the dependency.
                    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_${PN}-dev += "perl"
                    </literallayout>
                    In the example, the package name
                    (<filename>${PN}-dev</filename>) must appear as it would
                    in the
                    <filename><link linkend='var-PACKAGES'>PACKAGES</link></filename>
                    namespace before any renaming of the output package by
                    classes like <filename>debian.bbclass</filename>.
                </para>

                <para>
                    In many cases you do not need to explicitly add dependencies
                    to <filename>RDEPENDS</filename> since some automatic
                    handling occurs:
                    <itemizedlist>
                        <listitem><para><emphasis><filename>shlibdeps</filename></emphasis>:  If
                            a run-time package contains a shared library
                            (<filename>.so</filename>), the build
                            processes the library in order to determine other
                            libraries to which it is dynamically linked.
                            The build process adds these libraries to
                            <filename>RDEPENDS</filename> when creating the run-time
                            package.</para></listitem>
                        <listitem><para><emphasis><filename>pcdeps</filename></emphasis>:  If
                            the package ships a <filename>pkg-config</filename>
                            information file, the build process uses this file
                            to add items to the <filename>RDEPENDS</filename>
                            variable to create the run-time packages.
                            </para></listitem>
                    </itemizedlist>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-RM_WORK_EXCLUDE'><glossterm>RM_WORK_EXCLUDE</glossterm>
            <glossdef>
                <para>
                    With <filename>rm_work</filename> enabled, this
                    variable specifies a list of packages whose work directories
                    should not be removed.
                    See the "<link linkend='ref-classes-rm-work'>Removing Work Files During the Build - <filename>rm_work.bbclass</filename></link>"
                    section for more details.
                </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>).
                    <note>
                        A package's own name is implicitly already in its
                        <filename>RPROVIDES</filename> list.
                    </note>
                </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>
                    The OpenEmbedded build process automatically installs the list of packages
                    as part of the built package.
                    However, you can remove them later if you want.
                    If, during the build, a package from the list cannot be found, the build
                    process continues without an error.
                </para>
                <para>
                    Because the <filename>RRECOMMENDS</filename> variable applies to packages
                    being built, you should
                    always attach an override to the variable to specify the particular package
                    whose usability is being extended.
                    For example, suppose you are building a development package that is extended
                    to support wireless functionality.
                    In this case, you would use the following:
                    <literallayout class='monospaced'>
     RRECOMMENDS_${PN}-dev += "&lt;wireless_package_name&gt;"
                    </literallayout>
                    In the example, the package name
                    (<filename>${<link linkend='var-PN'>PN</link>}-dev</filename>)
                    must appear as it would in the
                    <filename><link linkend='var-PACKAGES'>PACKAGES</link></filename> namespace before any
                    renaming of the output package by classes like <filename>debian.bbclass</filename>.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-RREPLACES'><glossterm>RREPLACES</glossterm>
            <glossdef>
                <para>
                    A list of packages replaced by a package.
                    The package manager uses this variable to determine which
                    package should be installed to replace other package(s)
                    during an upgrade.
                    In order to also have the other package(s) removed at the
                    same time, you must add the name of the other
                    package to the
                    <filename><link linkend='var-RCONFLICTS'>RCONFLICTS</link></filename> variable.
                </para>
                <para>
                   As with all package-controlling variables, you must use
                   this variable in conjunction with a package name
                   override.
                   Here is an example:
                   <literallayout class='monospaced'>
     RREPLACES_${PN} = "other-package-being-replaced"
                   </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-RSUGGESTS'><glossterm>RSUGGESTS</glossterm>
            <glossdef>
                <para>
                    A list of additional packages that you can suggest for
                    installation by the package manager at the time a package
                    is installed.
                    Not all package managers support this functionality.
                </para>
                <para>
                   As with all package-controlling variables, you must always
                   use this variable in conjunction with a package name
                   override.
                   Here is an example:
                   <literallayout class='monospaced'>
     RSUGGESTS_${PN} = "useful-package another-package"
                   </literallayout>
                </para>
            </glossdef>
        </glossentry>

    </glossdiv>

    <glossdiv id='var-glossary-s'><title>S</title>

        <glossentry id='var-S'><glossterm>S</glossterm>
            <glossdef>
                <para>
                    The location in the <ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>Build Directory</ulink>
                    where unpacked package source code resides.
                    This location is within the working directory
                    (<filename><link linkend='var-WORKDIR'>WORKDIR</link></filename>), which
                    is not static.
                    The unpacked source location depends on the package name
                    (<filename><link linkend='var-PN'>PN</link></filename>) and
                    package version (<filename><link linkend='var-PV'>PV</link></filename>) as
                    follows:
                    <literallayout class='monospaced'>
 ${WORKDIR}/${PN}/${PV}
                    </literallayout>
                    As an example, assume a
                    <ulink url='&YOCTO_DOCS_DEV_URL;#source-directory'>Source Directory</ulink> top-level
                    folder named <filename>poky</filename> and a default Build
                    Directory at <filename>poky/build</filename>.
                    In this case, the working directory the build system uses to build
                    the <filename>db</filename> package is the following:
                    <literallayout class='monospaced'>
 ~/poky/build/tmp/work/qemux86-poky-linux/db/5.1.19-r3/db-5.1.19
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SANITY_TESTED_DISTROS'><glossterm>SANITY_TESTED_DISTROS</glossterm>
            <glossdef>
                <para>
                    A list of the host distribution identifiers that the
                    build system has been tested against.
                    Identifiers consist of the host distributor ID
                    followed by the release,
                    as reported by the <filename>lsb_release</filename> tool
                    or as read from <filename>/etc/lsb-release</filename>.
                    Separate the list items with explicit newline
                    characters (<filename>\n</filename>).
                    If <filename>SANITY_TESTED_DISTROS</filename> is not empty
                    and the current value of
                    <link linkend='var-NATIVELSBSTRING'><filename>NATIVELSBSTRING</filename></link>
                    does not appear in the list, then the build system reports
                    a warning that indicates the current host distribution has
                    not been tested as a build host.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SDKIMAGE_FEATURES'><glossterm>SDKIMAGE_FEATURES</glossterm>
            <glossdef>
                <para>Equivalent to
                    <filename><link linkend='var-IMAGE_FEATURES'>IMAGE_FEATURES</link></filename>.
                    However, this variable applies to the SDK generated from an
                    image using the following command:
                    <literallayout class='monospaced'>
     $ bitbake -c populate_sdk imagename
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SECTION'><glossterm>SECTION</glossterm>
            <glossdef>
                <para>The section in which packages should be categorized.
                    Package management utilities can make use of this variable.</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SELECTED_OPTIMIZATION'><glossterm>SELECTED_OPTIMIZATION</glossterm>
            <glossdef>
                <para>
                    The variable takes the value of
                    <filename><link linkend='var-FULL_OPTIMIZATION'>FULL_OPTIMIZATION</link></filename>
                    unless <filename><link linkend='var-DEBUG_BUILD'>DEBUG_BUILD</link></filename> = "1".
                    In this case the value of
                    <filename><link linkend='var-DEBUG_OPTIMIZATION'>DEBUG_OPTIMIZATION</link></filename> is used.
                </para>
            </glossdef>
        </glossentry>


        <glossentry id='var-SERIAL_CONSOLE'><glossterm>SERIAL_CONSOLE</glossterm>
            <glossdef>
                <para>The speed and device for the serial port used to attach the serial console.
                    This variable is given to the kernel as the "console"
                    parameter and after booting occurs <filename>getty</filename> is started on that port
                    so remote login is possible.</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SIGGEN_EXCLUDERECIPES_ABISAFE'><glossterm>SIGGEN_EXCLUDERECIPES_ABISAFE</glossterm>
            <glossdef>
                <para>
                    A list of recipes that are completely stable and will
                    never change.
                    The ABI for the recipes in the list are presented by
                    output from the tasks run to build the recipe.
                    Use of this variable is one way to remove dependencies from
                    one recipe on another that affect task signatures and
                    thus force rebuilds when the recipe changes.
                    <caution>
                        If you add an inappropriate variable to this list,
                        the software might break at runtime if the
                        interface of the recipe was changed after the other
                        had been built.
                    </caution>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SIGGEN_EXCLUDE_SAFE_RECIPE_DEPS'><glossterm>SIGGEN_EXCLUDE_SAFE_RECIPE_DEPS</glossterm>
            <glossdef>
                <para>
                    A list of recipe dependencies that should not be used to
                    determine signatures of tasks from one recipe when they
                    depend on tasks from another recipe.
                    For example:
                    <literallayout class='monospaced'>
    SIGGEN_EXCLUDE_SAFE_RECIPE_DEPS += "intone->mplayer2"
                    </literallayout>
                    In this example, <filename>intone</filename> depends on
                    <filename>mplayer2</filename>.
                </para>

                <para>
                    Use of this variable is one mechanism to remove dependencies
                    that affect task signatures and thus force rebuilds when a
                    recipe changes.
                    <caution>
                        If you add an inappropriate dependency for a recipe
                        relationship, the software might break during
                        runtime if the interface of the second recipe was
                        changed after the first recipe had been built.
                    </caution>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SITEINFO_ENDIANNESS'><glossterm>SITEINFO_ENDIANNESS</glossterm>
            <glossdef>
                <para>
                    Specifies the endian byte order of the target system.
                    The value should be either "le" for little-endian or "be" for big-endian.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SITEINFO_BITS'><glossterm>SITEINFO_BITS</glossterm>
            <glossdef>
                <para>
                    Specifies the number of bits for the target system CPU.
                    The value should be either "32" or "64".
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SOC_FAMILY'><glossterm>SOC_FAMILY</glossterm>
            <glossdef>
                <para>
                    Groups together machines based upon the same family
                    of SOC (System On Chip).
                    You typically set this variable in a common
                    <filename>.inc</filename> file that you include in the
                    configuration files of all the machines.
                    <note>
                        You must include
                        <filename>conf/machine/include/soc-family.inc</filename>
                        for this variable to appear in
                    <link linkend='var-MACHINEOVERRIDES'><filename>MACHINEOVERRIDES</filename></link>.
                    </note>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SPECIAL_PKGSUFFIX'><glossterm>SPECIAL_PKGSUFFIX</glossterm>
            <glossdef>
                <para>
                    A list of prefixes for <link linkend='var-PN'><filename>PN</filename></link> used by the
                    OpenEmbedded build system to create variants of recipes or packages.
                    The list specifies the prefixes to strip off during certain circumstances
                    such as the generation of the <link linkend='var-BPN'><filename>BPN</filename></link> variable.
                </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 the OpenEmbedded build system which bits
                    to pull in for the build and how to pull them in.
                    For example, if the recipe or append file only needs to
                    fetch a tarball from the Internet, the recipe or
                    append file uses a single <filename>SRC_URI</filename>
                    entry.
                    On the other hand, if the recipe or append file needs to
                    fetch a tarball, apply two patches, and include a custom
                    file, the recipe or append file would include four
                    instances of the variable.</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
                            <ulink url='&YOCTO_DOCS_DEV_URL;#metadata'>Metadata</ulink>,
                            from the local machine.
                            The path is relative to the
                            <link linkend='var-FILESPATH'><filename>FILESPATH</filename></link>
                            variable.
                            Thus, the build system searches, in order, from the
                            following directories, which are assumed to be a
                            subdirectories of the directory in which the
                            recipe file (<filename>.bb</filename>) or
                            append file (<filename>.bbappend</filename>)
                            resides:
                            <itemizedlist>
                                <listitem><para><emphasis><filename>${BPN}</filename> -</emphasis>
                                    The base recipe name without any special
                                    suffix or version numbers.
                                    </para></listitem>
                                <listitem><para><emphasis><filename>${BP}</filename> -</emphasis>
                                    <filename>${<link linkend='var-BPN'>BPN</link>}-${PV}</filename>.
                                    The base recipe name and version but without
                                    any special package name suffix.
                                    </para></listitem>
                                <listitem><para><emphasis>files -</emphasis>
                                    Files within a directory, which is named
                                    <filename>files</filename> and is also
                                    alongside the recipe or append file.
                                    </para></listitem>
                            </itemizedlist>
                            <note>
                                If you want the build system to pick up files
                                specified through a
                                <filename>SRC_URI</filename>
                                statement from your append file, you need to be
                                sure to extend the
                                <filename>FILESPATH</filename>
                                variable by also using the
                                <link linkend='var-FILESEXTRAPATHS'><filename>FILESEXTRAPATHS</filename></link>
                                variable from within your append file.
                            </note>
                            </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>svk://</filename> -</emphasis> Fetches files from
                            an SVK revision control repository.</para></listitem>
                        <listitem><para><emphasis><filename>http://</filename> -</emphasis> Fetches files from
                            the Internet using <filename>http</filename>.</para></listitem>
                        <listitem><para><emphasis><filename>https://</filename> -</emphasis> Fetches files
                            from the Internet using <filename>https</filename>.</para></listitem>
                        <listitem><para><emphasis><filename>ftp://</filename> -</emphasis> Fetches files
                            from the Internet using <filename>ftp</filename>.</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>Standard and recipe-specific options for <filename>SRC_URI</filename> exist.
                    Here are standard options:
                    <itemizedlist>
                        <listitem><para><emphasis><filename>apply</filename> -</emphasis> Whether to apply
                            the patch or not.
                            The default action is to apply the patch.</para></listitem>
                        <listitem><para><emphasis><filename>striplevel</filename> -</emphasis> Which
                            striplevel to use when applying the patch.
                            The default level is 1.</para></listitem>
                    </itemizedlist>
                </para>
                <para>Here are options specific to recipes building code from a revision control system:
                    <itemizedlist>
                        <listitem><para><emphasis><filename>mindate</filename> -</emphasis>
                            Apply the patch only if
                            <link linkend='var-SRCDATE'><filename>SRCDATE</filename></link>
                            is equal to or greater than <filename>mindate</filename>.
                            </para></listitem>
                        <listitem><para><emphasis><filename>maxdate</filename> -</emphasis>
                            Apply the patch only if <filename>SRCDATE</filename>
                            is not later than <filename>mindate</filename>.
                            </para></listitem>
                        <listitem><para><emphasis><filename>minrev</filename> -</emphasis>
                            Apply the patch only if <filename>SRCREV</filename>
                            is equal to or greater than <filename>minrev</filename>.
                            </para></listitem>
                        <listitem><para><emphasis><filename>maxrev</filename> -</emphasis>
                            Apply the patch only if <filename>SRCREV</filename>
                            is not later than <filename>maxrev</filename>.
                            </para></listitem>
                        <listitem><para><emphasis><filename>rev</filename> -</emphasis>
                            Apply the patch only if <filename>SRCREV</filename>
                            is equal to <filename>rev</filename>.
                            </para></listitem>
                        <listitem><para><emphasis><filename>notrev</filename> -</emphasis>
                            Apply the patch only if <filename>SRCREV</filename>
                            is not equal to <filename>rev</filename>.
                            </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 of <link linkend='var-WORKDIR'><filename>WORKDIR</filename></link>.
                            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-SRC_URI_OVERRIDES_PACKAGE_ARCH'><glossterm>SRC_URI_OVERRIDES_PACKAGE_ARCH</glossterm>
            <glossdef>
                <para></para>
                <para>
                    By default, the OpenEmbedded build system automatically detects whether
                    <filename><link linkend='var-SRC_URI'>SRC_URI</link></filename>
                    contains files that are machine-specific.
                    If so, the build system automatically changes
                    <filename><link linkend='var-PACKAGE_ARCH'>PACKAGE_ARCH</link></filename>.
                    Setting this variable to "0" disables this behavior.
                </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-SRCPV'><glossterm>SRCPV</glossterm>
            <glossdef>
                <para>
                    Returns the version string of the current package.
                    This string is used to help define the value of
                    <link linkend='var-PV'><filename>PV</filename></link>.
                </para>

                <para>
                    The <filename>SRCPV</filename> variable is defined in the
                    <filename>meta/conf/bitbake.conf</filename> configuration
                    file in the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#source-directory'>Source Directory</ulink>
                    as follows:
                    <literallayout class='monospaced'>
     SRCPV = "${@bb.fetch2.get_srcrev(d)}"
                    </literallayout>
                </para>

                <para>
                    Recipes that need to define <filename>PV</filename> do so
                    with the help of the <filename>SRCPV</filename>.
                    For example, the <filename>ofono</filename> recipe
                    (<filename>ofono_git.bb</filename>) located in
                    <filename>meta/recipes-connectivity</filename> in the
                    Source Directory defines <filename>PV</filename> as
                    follows:
                    <literallayout class='monospaced'>
     PV = "1.5.0+git${SRCPV}"
                    </literallayout>
                </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 to Subversion, Git, Mercurial and Bazaar
                    only.
                    Note that if you wish to build a fixed revision and you wish
                    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-SSTATE_DIR'><glossterm>SSTATE_DIR</glossterm>
            <glossdef>
                <para>The directory for the shared state cache.</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SSTATE_MIRRORS'><glossterm>SSTATE_MIRRORS</glossterm>
            <glossdef>
                <para>
                    Configures the OpenEmbedded build system to search other
                    mirror locations for prebuilt cache data objects before
                    building out the data.
                    This variable works like fetcher
                    <link linkend='var-MIRRORS'><filename>MIRRORS</filename></link>
                    and <link linkend='var-PREMIRRORS'><filename>PREMIRRORS</filename></link>
                    and points to the cache locations to check for the shared
                    objects.
                </para>

                <para>
                    You can specify a filesystem directory or a remote URL such
                    as HTTP or FTP.
                    The locations you specify need to contain the shared state
                    cache (sstate-cache) results from previous builds.
                    The sstate-cache you point to can also be from builds on
                    other machines.
                </para>

                <para>
                    If a mirror uses the same structure as
                    <link linkend='var-SSTATE_DIR'><filename>SSTATE_DIR</filename></link>,
                    you need to add
                    "PATH" at the end as shown in the examples below.
                    The build system substitutes the correct path within the
                    directory structure.
                    <literallayout class='monospaced'>
     SSTATE_MIRRORS ?= "\
     file://.* http://someserver.tld/share/sstate/PATH \n \
     file://.* file:///some/local/dir/sstate/PATH"
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-STAGING_KERNEL_DIR'><glossterm>STAGING_KERNEL_DIR</glossterm>
            <glossdef>
                <para>
                    The directory with kernel headers that are required to build out-of-tree
                    modules.
                </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.
                    Currently, the default assignment for <filename>STAMP</filename>
                    as set in the <filename>meta/conf/bitbake.conf</filename> file
                    is:
                    <literallayout class='monospaced'>
     STAMP = "${STAMPS_DIR}/${MULTIMACH_TARGET_SYS}/${PN}/${EXTENDPE}${PV}-${PR}"
                    </literallayout>
                    See <link linkend='var-STAMPS_DIR'><filename>STAMPS_DIR</filename></link>,
                    <link linkend='var-MULTIMACH_TARGET_SYS'><filename>MULTIMACH_TARGET_SYS</filename></link>,
                    <link linkend='var-PN'><filename>PN</filename></link>,
                    <link linkend='var-EXTENDPE'><filename>EXTENDPE</filename></link>,
                    <link linkend='var-PV'><filename>PV</filename></link>, and
                    <link linkend='var-PR'><filename>PR</filename></link> for related variable
                    information.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-STAMPS_DIR'><glossterm>STAMPS_DIR</glossterm>
            <glossdef>
                <para>
                    Specifies the base directory in which the OpenEmbedded
                    build system places stamps.
                    The default directory is
                    <filename>${TMPDIR}/stamps</filename>.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SUMMARY'><glossterm>SUMMARY</glossterm>
            <glossdef>
                <para>The short (72 characters or less) summary of the binary package for packaging
                    systems such as <filename>opkg</filename>, <filename>rpm</filename> or
                    <filename>dpkg</filename>.
                    By default, <filename>SUMMARY</filename> is used to define
                    the <link linkend='var-DESCRIPTION'><filename>DESCRIPTION</filename></link>
                    variable if <filename>DESCRIPTION</filename> is not set
                    in the recipe.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SYSROOT_PREPROCESS_FUNCS'><glossterm>SYSROOT_PREPROCESS_FUNCS</glossterm>
            <glossdef>
                <para>
                    A list of functions to execute after files are staged into
                    the sysroot.
                    These functions are usually used to apply additional
                    processing on the staged files, or to stage additional
                    files.
                </para>
            </glossdef>
        </glossentry>

    </glossdiv>

    <glossdiv id='var-glossary-t'><title>T</title>

        <glossentry id='var-T'><glossterm>T</glossterm>
            <glossdef>
                <para>This variable points to a directory were BitBake places
                    temporary files, which consist mostly of task logs and
                    scripts, when building a particular recipe.
                    The variable is typically set as follows:
                    <literallayout class='monospaced'>
     T = "${WORKDIR}/temp"
                    </literallayout>
                    The <link linkend='var-WORKDIR'><filename>WORKDIR</filename></link>
                    is the directory into which BitBake unpacks and builds the
                    recipe.
                    The default <filename>bitbake.conf</filename> file sets this variable.</para>
                    <para>The <filename>T</filename> variable is not to be confused with
                    the <link linkend='var-TMPDIR'><filename>TMPDIR</filename></link> variable,
                    which points to the root of the directory tree where BitBake
                    places the output of an entire build.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-TARGET_ARCH'><glossterm>TARGET_ARCH</glossterm>
            <glossdef>
                <para>The architecture of the device being built.
                    The OpenEmbedded build system supports the following
                    architectures:
                    <literallayout class='monospaced'>
     arm
     mips
     ppc
     x86
     x86-64
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-TARGET_CFLAGS'><glossterm>TARGET_CFLAGS</glossterm>
            <glossdef>
                <para>
                    Flags passed to the C compiler for the target system.
                    This variable evaluates to the same as
                    <filename><link linkend='var-CFLAGS'>CFLAGS</link></filename>.
                </para>
            </glossdef>
        </glossentry>


        <glossentry id='var-TARGET_FPU'><glossterm>TARGET_FPU</glossterm>
            <glossdef>
                <para>Specifies the method for handling FPU code.
                    For FPU-less targets, which include most ARM CPUs, the variable must be
                    set to "soft".
                    If not, the kernel emulation gets used, which results in a performance penalty.</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-TARGET_OS'><glossterm>TARGET_OS</glossterm>
            <glossdef>
                <para>Specifies the target's operating system.
                    The variable can be set to "linux" for <filename>eglibc</filename>-based systems and
                    to "linux-uclibc" for <filename>uclibc</filename>.
                    For ARM/EABI targets, there are also "linux-gnueabi" and
                    "linux-uclibc-gnueabi" values possible.</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-TCLIBC'><glossterm>TCLIBC</glossterm>
            <glossdef>
                <para>
                    Specifies which variant of the GNU standard C library (<filename>libc</filename>)
                    to use during the build process.
                    This variable replaces <filename>POKYLIBC</filename>, which is no longer
                    supported.
                </para>
                <para>
                    You can select <filename>eglibc</filename> or <filename>uclibc</filename>.
                    <note>
                        This release of the Yocto Project does not support the
                        <filename>glibc</filename> implementation of <filename>libc</filename>.
                    </note>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-TCMODE'><glossterm>TCMODE</glossterm>
            <glossdef>
                <para>
                    The toolchain selector.
                    This variable replaces <filename>POKYMODE</filename>, which is no longer
                    supported.
                </para>
                <para>
                    The <filename>TCMODE</filename> variable selects the external toolchain
                    built using the OpenEmbedded build system or a few supported combinations of
                    the upstream GCC or CodeSourcery Labs toolchain.
                    The variable identifies the <filename>tcmode-*</filename> files used in
                    the <filename>meta/conf/distro/include</filename> directory, which is found in the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#source-directory'>Source Directory</ulink>.
                </para>
                <para>
                    By default, <filename>TCMODE</filename> is set to "default", which
                    chooses the <filename>tcmode-default.inc</filename> file.
                    The variable is similar to
                    <link linkend='var-TCLIBC'><filename>TCLIBC</filename></link>, which controls
                    the variant of the GNU standard C library (<filename>libc</filename>)
                    used during the build process: <filename>eglibc</filename> or <filename>uclibc</filename>.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-THISDIR'><glossterm>THISDIR</glossterm>
            <glossdef>
                <para>
                    The directory in which the file BitBake is currently
                    parsing is located.
                    Do not manually set this variable.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-TMPDIR'><glossterm>TMPDIR</glossterm>
            <glossdef>
                <para>
                    This variable is the temporary directory the OpenEmbedded build system
                    uses when it does its work building images.
                    By default, the <filename>TMPDIR</filename> variable is named
                    <filename>tmp</filename> within the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>Build Directory</ulink>.
                </para>

                <para>
                    If you want to establish this directory in a location other than the
                    default, you can uncomment the following statement in the
                    <filename>conf/local.conf</filename> file in the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#source-directory'>Source Directory</ulink>:
                    <literallayout class='monospaced'>
     #TMPDIR = "${TOPDIR}/tmp"
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-TOPDIR'><glossterm>TOPDIR</glossterm>
            <glossdef>
                <para>
                    This variable is the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>Build Directory</ulink>.
                    BitBake automatically sets this variable.
                    The OpenEmbedded build system uses the Build Directory when building images.
                </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>

        <glossentry id='var-WORKDIR'><glossterm>WORKDIR</glossterm>
            <glossdef>
                <para>
                    The pathname of the working directory in which the OpenEmbedded build system
                    builds a recipe.
                    This directory is located within the
                    <link linkend='var-TMPDIR'><filename>TMPDIR</filename></link> directory structure and changes
                    as different packages are built.
                </para>

                <para>
                    The actual <filename>WORKDIR</filename> directory depends on several things:
                    <itemizedlist>
                        <listitem>The temporary directory - <link linkend='var-TMPDIR'><filename>TMPDIR</filename></link></listitem>
                        <listitem>The package architecture - <link linkend='var-PACKAGE_ARCH'><filename>PACKAGE_ARCH</filename></link></listitem>
                        <listitem>The target machine - <link linkend='var-MACHINE'><filename>MACHINE</filename></link></listitem>
                        <listitem>The target operating system - <link linkend='var-TARGET_OS'><filename>TARGET_OS</filename></link></listitem>
                        <listitem>The recipe name - <link linkend='var-PN'><filename>PN</filename></link></listitem>
                        <listitem>The recipe version - <link linkend='var-PV'><filename>PV</filename></link></listitem>
                        <listitem>The recipe revision - <link linkend='var-PR'><filename>PR</filename></link></listitem>
                    </itemizedlist>
                </para>

                <para>
                    For packages that are not dependent on a particular machine,
                    <filename>WORKDIR</filename> is defined as follows:
                    <literallayout class='monospaced'>
 ${TMPDIR}/work/${PACKAGE_ARCH}-poky-${TARGET_OS}/${PN}/${PV}-${PR}
                    </literallayout>
                    As an example, assume a
                    <ulink url='&YOCTO_DOCS_DEV_URL;#source-directory'>Source Directory</ulink> top-level
                    folder name <filename>poky</filename> and a default
                    <ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>Build Directory</ulink>
                    at <filename>poky/build</filename>.
                    In this case, the working directory the build system uses to build
                    the <filename>v86d</filename> package is the following:
                    <literallayout class='monospaced'>
     ~/poky/build/tmp/work/qemux86-poky-linux/v86d/01.9-r0
                    </literallayout>
                </para>

                <para>
                    For packages that are dependent on a particular machine, <filename>WORKDIR</filename>
                    is defined slightly different:
                    <literallayout class='monospaced'>
 ${TMPDIR}/work/${MACHINE}-poky-${TARGET_OS}/${PN}/${PV}-${PR}
                    </literallayout>
                    As an example, again assume a Source Directory top-level folder
                    named <filename>poky</filename> and a default Build Directory
                    at <filename>poky/build</filename>.
                    In this case, the working directory the build system uses to build
                    the <filename>acl</filename> recipe, which is being built for a
                    MIPS-based device, is the following:
                    <literallayout class='monospaced'>
     ~/poky/build/tmp/work/mips-poky-linux/acl/2.2.51-r2
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

    </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>
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