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

<!DOCTYPE appendix PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">

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

<title>Reference: Variables Glossary</title>

<para>
    This section lists common variables used in the Yocto Project and gives an overview
    of their function and contents.
</para>

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


    <para>
       <link linkend='var-AUTHOR'>A</link> 
       <link linkend='var-BAD_RECOMMENDATIONS'>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-KERNEL_FEATURES'>K</link>
       <link linkend='var-LAYERDIR'>L</link> 
       <link linkend='var-MACHINE'>M</link> 
<!--               <link linkend='var-glossary-n'>N</link> -->
<!--               <link linkend='var-glossary-o'>O</link> -->
       <link linkend='var-PACKAGE_ARCH'>P</link> 
<!--               <link linkend='var-glossary-q'>Q</link> -->
       <link linkend='var-RCONFLICTS'>R</link> 
       <link linkend='var-S'>S</link> 
       <link linkend='var-TARGET_ARCH'>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-AUTHOR'><glossterm>AUTHOR</glossterm>
            <glossdef>
                <para>The email address used to contact the original author or authors in 
                    order to send patches, forward bugs, etc.</para>
            </glossdef>
         </glossentry>

        <glossentry id='var-AUTOREV'><glossterm>AUTOREV</glossterm>
            <glossdef>
                <para>Specifies to use the current (newest) source revision.
                    This variable is with the <filename><link linkend='var-SRCREV'>SRCREV</link></filename>
                    variable.</para>
            </glossdef>
        </glossentry>

    </glossdiv> 

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

        <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 for images that use the 
                    <filename>ipkg</filename> packaging system.</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-BBMASK'><glossterm>BBMASK</glossterm>
            <glossdef>
                <para>Prevents BitBake from processing recipes and recipe append files.
                    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.
                    For complete syntax information, see python's documentation at 
                    <ulink url='http://docs.python.org/release/2.3/lib/re-syntax.html'></ulink>.
                    The expression is compared against the full paths to the files. 
                    For example, the following 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></para>
                <para>Use the <filename>BBMASK</filename> variable from within the 
                    <filename>conf/local.conf</filename> file found 
                    in the Yocto Project build directory.</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 mulitiple 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 <filename>BBFILES</filename> 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 package appears in
                    more than one layer. 
                    Setting this variable allows you to prioritize a
                    layer against other layers that contain the same package - effectively
                    letting you control the precedence for the multiple layers. 
                    The precedence established through this variable stands regardless of a
                    layer's package version (<filename>PV</filename> variable). 
                    For example, a layer that has a package 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 Yocto Project build. 
                    This variable is defined in the <filename>bblayers.conf</filename> configuration 
                    file in the Yocto Project build directory. 
                    Here is an example:
                    <literallayout class='monospaced'>
     BBLAYERS = " \
       /home/scottrif/poky/meta \
       /home/scottrif/poky/meta-yocto \
       /home/scottrif/poky/meta-mykernel \
       "
                    </literallayout>
                    This example enables three layers, one of which is a custom, user-defined layer 
                    named <filename>meta-mykernel</filename>.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-BPN'><glossterm>BPN</glossterm>
            <glossdef>
                <para>Bare name of package with any suffixes like -cross -native removed.</para>
            </glossdef>
        </glossentry>

    </glossdiv>

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

        <glossentry id='var-CFLAGS'><glossterm>CFLAGS</glossterm>
            <glossdef>
                <para>
                    Flags passed to 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-COMPATIBLE_MACHINE'><glossterm>COMPATIBLE_MACHINE</glossterm>
            <glossdef>
                <para>A regular expression which evaluates to match the machines the recipe 
                    works with. 
                    It stops recipes being run on machines for which they are not compatible. 
                    This is particularly useful with kernels. 
                    It also helps to increase parsing speed as further parsing of the recipe is skipped 
                    if it is found the current machine is not compatible.</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 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 Yocto Project
                    files directory.
                </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>

    </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 the priority of recipes.</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-DEPENDS'><glossterm>DEPENDS</glossterm>
            <glossdef>
                <para>
                    A list of build-time dependencies for a given recipe. 
                    The variable indicates recipes that must have been staged before a 
                    particular recipe can configure.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-DESCRIPTION'><glossterm>DESCRIPTION</glossterm>
            <glossdef>
                <para>The package description used by package managers.</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.</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-DISTRO_EXTRA_RRECOMMENDS'><glossterm>DISTRO_EXTRA_RRECOMMENDS</glossterm>
            <glossdef>
                <para></para>
                <para>The list of packages which extend usability of the image. 
                    Those packages will automatically be installed but can be removed by user.</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-DISTRO_FEATURES'><glossterm>DISTRO_FEATURES</glossterm>
            <glossdef>
                <para>The features of the distribution.</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='http://www.yoctoproject.org/docs/latest/dev-manual/dev-manual.html#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-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 
                    Yocto Project build directory.
                    <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, see the
                    "<link linkend='how-does-the-yocto-project-obtain-source-code-and-will-it-work-behind-my-firewall-or-proxy-server'>FAQ</link>"
                    appendix.
                </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
                    to be generated during the build (useful if the target device has 64Mbytes
                    of RAM or less).</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-EXTRA_IMAGE_FEATURES'><glossterm>EXTRA_IMAGE_FEATURES</glossterm>
            <glossdef>
                <para>Allows extra packages to be added to the generated images.
                    You set this variable in the <filename>local.conf</filename>
                    configuration file.
                    Note that some image features are also added using the 
                    <filename><link linkend='var-IMAGE_FEATURES'>IMAGE_FEATURES</link></filename>
                    variable generally configured in image recipes.
                    You can use this variable to add more features in addition to those.
                    Here are some examples of features you can add:</para>
                    <literallayout class='monospaced'>
"dbg-pkgs" - Adds -dbg packages for all installed packages
             including symbol information for debugging and 
             profiling.

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

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

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

"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.  
                       
                 There are other application targets too, see
                 <filename>meta/classes/poky-image.bbclass</filename>
                 and <filename>meta/packages/tasks/task-poky.bb</filename>
                 for more details.
                    </literallayout> 
            </glossdef>
        </glossentry>

        <glossentry id='var-EXTRA_IMAGEDEPENDS'><glossterm>EXTRA_IMAGEDEPENDS</glossterm>
            <glossdef>
                <para>A list of recipes to be built that do not provide packages to be installed in
                    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>*DEPENDS</filename> and <filename>*RECOMMENDS</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 package.
                    Then, provide a space-separated list of files or paths that identifies the 
                    files you want included as part of the 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 Yocto Project
                    files directory.
                </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-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 Yocto Project uses the <filename>fs-perms.txt</filename>, which
                    is located in the <filename>meta/files</filename> directory of the Yocto Project
                    files directory.
                    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 Yocto Project's 
                    build directory, 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 
                    <filename>BBPATH</filename> 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 optimised 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 info about package can be found</para>
            </glossdef>
        </glossentry>

    </glossdiv>

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

        <glossentry id='var-IMAGE_FEATURES'><glossterm>IMAGE_FEATURES</glossterm>
            <glossdef>
                <para>The list of features present in images.
                Typically, you configure this variable in image recipes.
                Note that you can add extra features to the image by using the
                <filename><link linkend='var-EXTRA_IMAGE_FEATURES'>EXTRA_IMAGE_FEATURES</link></filename> variable.
                See the "<link linkend="ref-features-image">Reference: Images</link>" section for the 
                list of features present in images built by the Yocto Project.</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_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 Yocto Project 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>
<!--                    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>Defines the Package revision.  
                    You manually combine values for <filename>INC_PR</filename> into the 
                    <filename>PR</filename> field of the parent recipe.
                    When you change this variable, you change the <filename>PR</filename>
                    value for every person that includes the file.</para>
                <para>
                    The following example shows how to use the <filename>INC_PR</filename> variable
                    given a common <filename>.inc</filename> file that defines the variable.
                    Once defined, you can use the variable to set the <filename>PR</filename> value:
                </para>
                <literallayout class='monospaced'>
 recipes-graphics/xorg-font/font-util_1.1.1.bb:PR - "$(INC_PR).1"
 recipes-graphics/xorg-font/xorg-font-common.inc:INC_PR - "r1"
 recipes-graphics/xorg-font/encondings_1.0.3.bb:PR - "$(INC_PR).1"
 recipes-graphics/xorg-font/fiont-alias_1.0.2.bb:PR - "$(INC_PR).0"
                </literallayout>
            </glossdef>
        </glossentry>

        <glossentry id='var-INHIBIT_PACKAGE_STRIP'><glossterm>INHIBIT_PACKAGE_STRIP</glossterm>
            <glossdef>
                <para>
                    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 <filename>PN</filename> 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>.
                    An example is <filename>start 99 5 2 . stop 20 0 1 6 .</filename>, which gives the script 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>


    </glossdiv>

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

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

        <glossentry id='var-KERNEL_FEATURES'><glossterm>KERNEL_FEATURES</glossterm>
            <glossdef>
                <para>Includes additional metadata from the Linux Yocto kernel Git repository.
                    In the Yocto Project build system, the default Board Support Packages (BSPs)
                    metadata is provided through 
                    the <filename>KMACHINE</filename> and <filename>KBRANCH</filename> 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 Linux Yocto 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>

   </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 <filename>LAYERVERSION_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 requires immediate expansion
                    (see the BitBake manual) as lazy expansion can result in
                    the expansion happening in the wrong directory and therefore
                    giving the wrong value.</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 <filename>LAYERDEPENDS</filename> 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 <filename>LICENSE</filename>
                    is set to "CLOSED")</para>
                <para>For more information, see the
                    <link linkend='usingpoky-configuring-LIC_FILES_CHKSUM'>
                    Track License Change</link> section</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-LICENSE'><glossterm>LICENSE</glossterm>
            <glossdef>
                <para>The list of package source licenses.</para>
            </glossdef>
        </glossentry>

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

         <glossentry id='var-MACHINE_ESSENTIAL_EXTRA_RDEPENDS'><glossterm>MACHINE_ESSENTIAL_EXTRA_RDEPENDS</glossterm>
            <glossdef>
                <para></para>
                <para>
                    A list of required packages to install as part of the package 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>task-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 package 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>
                    For example, suppose you are building a runtime package that depends
                    on a certain disk driver.
                    In this case, you would use the following:
                    <literallayout class='monospaced'>
     MACHINE_ESSENTIAL_EXTRA_RDEPENDS += "&lt;disk_driver&gt;"
                    </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 packages to install as part of the package being 
                    built. 
                    The build process does not depend 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>task-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 package 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.
                    However, because this is one of the "essential" variables, the resulting image
                    might not boot on the machine. 
                    Or, if the machine does boot using the image, the machine might not be fully 
                    functional.
                </para>
                <para>
                    Consider an example where you have a custom kernel with a disk driver
                    built into the kernel itself, rather than using the driver built as a module.
                    If you include the package that has the driver module as part of 
                    the variable's list, the 
                    build process will not find that package.  
                    However, because these packages are "recommends" packages, the build will 
                    not fail due to the missing package.
                    Not accounting for any other problems, the custom kernel would still boot the machine.
                </para>
                <para>
                    Some example packages of these machine essentials are flash, screen, keyboard, mouse, 
                    or touchscreen drivers (depending on the machine).
                </para>
                <para>
                    For example, suppose you are building a runtime package that depends
                    on a mouse driver.
                    In this case, you would use the following:
                    <literallayout class='monospaced'>
     MACHINE_ESSENTIAL_EXTRA_RRECOMMENDS += "&lt;mouse_driver&gt;"
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

         <glossentry id='var-MACHINE_EXTRA_RDEPENDS'><glossterm>MACHINE_EXTRA_RDEPENDS</glossterm>
            <glossdef>
                <para>
                    A list of optional but non-machine essential packages to install as 
                    part of the package being built.
                    Even though these packages are not essential for the machine to boot,  
                    the build process depends on them being present.
                    The impact of this variable affects all images based on
                    <filename>task-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_RRECOMMENDS'>MACHINE_EXTRA_RRECOMMENDS</link></filename>
                    variable with the exception that the package 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 might or might not have a WiFi card.
                    The package containing the WiFi support is not essential for the 
                    machine to boot the image.
                    If it is not there, the machine will boot but not be able to use the 
                    WiFi functionality.
                    However, if you include the package with the WiFi support as part of the 
                    variable's package list, the build 
                    process depends on finding the package.
                    In this case, you would use the following:
                    <literallayout class='monospaced'>
     MACHINE_EXTRA_RDEPENDS += "&lt;wifi_driver&gt;"
                    </literallayout>
                </para>
            </glossdef>
         </glossentry>

         <glossentry id='var-MACHINE_EXTRA_RRECOMMENDS'><glossterm>MACHINE_EXTRA_RRECOMMENDS</glossterm>
            <glossdef>
                <para></para>
                <para>
                    A list of optional but non-machine essential packages to install as 
                    part of the package being built.
                    The package being built has no build dependency on the list of packages 
                    with this variable.  
                    The impact of this variable affects only images based on 
                    <filename>task-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 package 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 might or might not have a WiFi card.
                    The package containing the WiFi support is not essential for the 
                    machine to boot the image.
                    If it is not there, the machine will boot but not be able to use the 
                    WiFi functionality.
                    You are free to either include or not include the 
                    the package with the WiFi support as part of the 
                    variable's package list, the build 
                    process does not depend on finding the package.
                    If you include the package, you would use the following:
                    <literallayout class='monospaced'>
     MACHINE_EXTRA_RRECOMMENDS += "&lt;wifi_driver&gt;"
                    </literallayout>
                </para>
            </glossdef>
         </glossentry>

         <glossentry id='var-MACHINE_FEATURES'><glossterm>MACHINE_FEATURES</glossterm>
            <glossdef>
                <para>Specifies the list of device features.
                    See the <link linkend='ref-features-machine'>Machine</link> section for 
                    more information.</para>
            </glossdef>
         </glossentry>

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

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

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

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

        <glossentry id='var-PACKAGE_ARCH'><glossterm>PACKAGE_ARCH</glossterm>
            <glossdef>
                <para>The architecture of the resulting 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 Yocto Project file's <filename>conf</filename> directory,
                    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_DESCRIPTION'><glossterm>PACKAGE_DESCRIPTION</glossterm>
            <glossdef>
                <para>The long form description of the binary package for packaging systems such as 
                    <filename>ipkg</filename>, <filename>rpm</filename> or <filename>debian</filename>.
                    By default, this variable inherits <filename>DESCRIPTION</filename>.</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-PACKAGE_SUMMARY'><glossterm>PACKAGE_SUMMARY</glossterm>
            <glossdef>
                <para>The short (72 character limit suggested) summary of the binary
                package for packaging systems such as <filename>ipkg</filename>, 
                <filename>rpm</filename> or <filename>debian</filename>.
                By default, this variable inherits <filename>DESCRIPTION</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 "${PN}-dbg ${PN} ${PN}-doc ${PN}-dev".</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-PN'><glossterm>PN</glossterm>
            <glossdef>
                <para>The name of the package.
                    </para>
            </glossdef>
        </glossentry>

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

        <glossentry id='var-PV'><glossterm>PV</glossterm>
            <glossdef>
                <para>The version of the package.
                    The version is normally extracted from the recipe name.
                    For example, if the recipe is named 
                    <filename>expat_2.0.1.bb</filename>, then <filename>PV</filename>
                    will be <filename>2.0.1</filename>. 
                    <filename>PV</filename> is generally not overridden within 
                    a recipe unless it is building an unstable 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 package. 
                    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. 
                    The variable must always be suffixed with the name of the 
                    provided item, and should be set to the 
                    <filename>$PN</filename> 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.
                    The variable must always be suffixed with the <filename>$PN</filename> 
                    for which to select, and should be set to the 
                    <filename>$PV</filename> to which you want to give 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>

        <glossentry id='var-POKY_EXTRA_INSTALL'><glossterm>POKY_EXTRA_INSTALL</glossterm>
            <glossdef>
                <para>Specifies the list of packages to be added to the image. 
                    This variable should only be set in the <filename>local.conf</filename>
                    configuration file found in the Yocto Project's build directory.</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-POKYLIBC'><glossterm>POKYLIBC</glossterm>
            <glossdef>
                <para>
                    This variable is no longer supported and has been replaced by the
                    <link linkend='var-TCLIBC'><filename>TCLIBC</filename></link> variable.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-POKYMODE'><glossterm>POKYMODE</glossterm>
            <glossdef>
                <para>
                    This variable is no longer supported and has been replaced by the
                    <link linkend='var-TCMODE'><filename>TCMODE</filename></link> variable.
                </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 this package.
                    Note that the package will not be installed if the conflicting packages are not
                    first removed.</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-RDEPENDS'><glossterm>RDEPENDS</glossterm>
            <glossdef>
                <para>
                    A list of packages that must be installed as part of a package being built.
                    The package being built has a runtime dependency on the packages in the 
                    variable's list.
                    In other words, in order for the package being built to run correctly, 
                    it depends on these listed packages.
                    If a package in this list cannot be found during the build, the build
                    will not complete.
                </para>
                <para>
                    Because the <filename>RDEPENDS</filename> variable applies to packages 
                    being built, you should 
                    always attach an override to the variable to specify the particular runtime 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>
                    Some automatic handling occurs around the <filename>RDEPENDS</filename>
                    variable:
                    <itemizedlist>
                        <listitem><para><emphasis><filename>shlibdeps</filename></emphasis>:  If a runtime
                            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>
                            to create the runtime 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 runtime packages.
                            </para></listitem>
                    </itemizedlist>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-RRECOMMENDS'><glossterm>RRECOMMENDS</glossterm>
            <glossdef>
                <para>
                    A list of packages that extend 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 Yocto Project 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_${PN}-dev += "&lt;wireless_package_name&gt;"
                    </literallayout>
                    In the example, the package name (<filename>${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>
            </glossdef>
        </glossentry>

        <glossentry id='var-RREPLACES'><glossterm>RREPLACES</glossterm>
            <glossdef>
                <para>The list of packages that are replaced with this package.</para>
            </glossdef>
        </glossentry>

    </glossdiv>

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

        <glossentry id='var-S'><glossterm>S</glossterm>
            <glossdef>
                <para>
                    The path to unpacked sources.
                    By default, this path is as follows:
                    <literallayout class='monospaced'>
     ${<link linkend='var-WORKDIR'>WORKDIR</link>}/${<link linkend='var-PN'>PN</link>}-${<link linkend='var-PV'>PV</link>}
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SECTION'><glossterm>SECTION</glossterm>
            <glossdef>
                <para>The section where package should be put.
                    Package managers use 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-SSTATE_DIR'><glossterm>SSTATE_DIR</glossterm>
            <glossdef>
                <para>The directory for the shared state.</para>
            </glossdef>

        </glossentry>
        <glossentry id='var-SHELLCMDS'><glossterm>SHELLCMDS</glossterm>
            <glossdef>
                <para>
                    A list of commands to run within the shell. 
                    The list is used by <filename><link linkend='var-TERMCMDRUN'>TERMCMDRUN</link></filename>.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SITEINFO_ENDIANNESS'><glossterm>SITEINFO_ENDIANNESS</glossterm>
            <glossdef>
                <para>
                    Specifies the endian byte order of the target system. 
                    The variable is 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 variable is either "32" or "64".
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SRC_URI'><glossterm>SRC_URI</glossterm>
            <glossdef>
                <para>The list of source files - local or remote.</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 Yocto Project automatically detects whether 
                    <filename><link linkend='var-SRC_URI'>SRC_URI</link></filename>  
                    contains files that are machine-specific.
                    If so, the Yocto Project automatically changes 
                    <filename><link linkend='var-PACKAGE_ARCH'>PACKAGE_ARCH</link></filename>. 
                    Setting this variable to "0" disables this behaviour.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SRCDATE'><glossterm>SRCDATE</glossterm>
            <glossdef>
                <para>
                    The date of the source code used to build the package.
                    This variable applies only if the source was fetched from a Source Code Manager (SCM).
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SRCREV'><glossterm>SRCREV</glossterm>
            <glossdef>
                <para>
                    The revision of the source code used to build the package.
                    This variable applies 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-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-STAMPS'><glossterm>STAMPS</glossterm>
            <glossdef>
                <para>
                    The directory (usually <filename>TMPDIR/stamps</filename>) with timestamps of
                    executed tasks.
                </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>ipkg</filename>, <filename>rpm</filename> or 
                    <filename>debian</filename>.
                    By default, this variable inherits <filename>DESCRIPTION</filename>.</para>
            </glossdef>
        </glossentry>

    </glossdiv>

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

        <glossentry id='var-TARGET_ARCH'><glossterm>TARGET_ARCH</glossterm>
            <glossdef>
                <para>The architecture of the device being built. 
                While a number of values are possible, the Yocto Project primarily supports
                <filename>arm</filename> and <filename>i586</filename>.</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 from the Yocto Project or a few supported combinations of
                    the upstream GCC or CodeSourcery Labs toolchain.
                    The variable determines which of the files in 
                    <filename>meta/conf/distro/include/tcmode-*</filename> is used. 
                </para>
                <para>
                    By default, <filename>TCMODE</filename> is set to "default", which 
                    chooses <filename>tcmode-default.inc</filename>.
                    The variable is similar to <filename>TCLIBC</filename>, 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-TERMCMD'><glossterm>TERMCMD</glossterm>
            <glossdef>
                <para>
                    This command is used by BitBake to launch a terminal window with a 
                    shell. 
                    The shell is unspecified so the user's default shell is used. 
                    By default, the variable is set to "xterm" but it can 
                    be any X11 terminal application or a terminal multiplexer such as screen.
                </para>
                <note>
                    While <filename>KONSOLE_TERMCMD</filename> and 
                    <filename>KONSOLE_TERMCMDRUN</filename> are provided
                    and will work with KDE's Konsole terminal application Konsole from KDE 3,
                    Konsole in KDE 4.0 and later versions will no longer work here due to the fact
                    that it now launches in the background by default, and it is not practically
                    possible to wait until it has terminated. 
                    It is hoped that this can be fixed
                    in a future version.
                </note>
            </glossdef>
        </glossentry>

        <glossentry id='var-TERMCMDRUN'><glossterm>TERMCMDRUN</glossterm>
            <glossdef>
                <para>
                    This variable is similar to 
                    <filename><link linkend='var-TERMCMD'>TERMCMD</link></filename>.
                    However, instead of running the user's shell, the command specified by 
                    the <filename><link linkend='var-SHELLCMDS'>SHELLCMDS</link></filename> 
                    variable is run.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-TOPDIR'><glossterm>TOPDIR</glossterm>
            <glossdef>
                <para>
                    This variable is the 
                    <ulink url='http://www.yoctoproject.org/docs/latest/dev-manual/dev-manual.html#yocto-project-build-directory'>
                    Yocto Project Build Directory</ulink>.
                    BitBake automatically sets this variable.
                    The Yocto Project 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 path to directory in <filename>tmp/work/</filename> where 
                    the package is built.</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>
</appendix>
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