path: root/meta/conf/documentation.conf

# this file holds documentation for known keys, possible values and
# their meaning. Please update, correct and extend this documentation.
# Mail your changes to openembedded-devel@openembedded.org

#A

ALLOW_EMPTY[doc] = "Specifies if an output package should still be produced if it is empty."
ASSUME_PROVIDED[doc] = "List of packages (recipes actually) which are assumed to be implicitly available. These packages won't be built by BitBake."
ASSUME_SHLIBS[doc] = "List of shlib:package[_version] mappings. Useful for lib packages in ASSUME_PROVIDED, for which automatic shlib dependency tracking doesn't work."
AUTHOR[doc] = "The email address used to contact the original author(s) in order to send patches and forward bugs."
AUTOREV[doc] = "When SRCREV is set to the value of this variable, it specifies to use the latest source revision in the repository."

#B

B[doc] = "The Build Directory. The OpenEmbedded build system places generated objects into the Build Directory during a recipe's build process."
BAD_RECOMMENDATIONS[doc] = "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."
BB_DANGLINGAPPENDS_WARNONLY[doc] = "Defines how BitBake handles situations where an append file (.bbappend) has no corresponding recipe file (.bb)."
BB_DISKMON_DIRS[doc] = "Monitors disk space and available inodes during the build and allows you to control the build based on these parameters."
BB_DISKMON_WARNINTERVAL[doc] = "Defines the disk space and free inode warning intervals. To set these intervals, define the variable in the conf/local.conf file in the Build Directory."
BBCLASSEXTEND[doc] = "Allows you to extend a recipe so that it builds variants of the software. Common variants for recipes are 'natives', 'crosses', 'nativesdk' and 'multilibs'."
BBMASK[doc] = "Prevents BitBake from processing recipes and recipe append files. Use the BBMASK variable from within the conf/local.conf file in the Build Directory."
BB_NUMBER_THREADS[doc] = "The maximum number of tasks BitBake should run in parallel at any one time. A good rule of thumb is to set this variable to twice the number of cores."
BBFILE_COLLECTIONS[doc] = "Lists the names of configured layers. These names are used to find the other BBFILE_* variables."
BBFILE_PATTERN[doc] = "Variable that expands to match files from BBFILES in a particular layer. This variable is used in the layer.conf file and must be suffixed with the name of a layer."
BBFILE_PRIORITY[doc] = "Assigns the priority for recipe files in each layer. Setting this variable allows you to prioritize a layer against other layers that contain the same recipe."
BBFILES[doc] = "List of recipe files used by BitBake to build software."
BBPATH[doc] = "Used by BitBake to locate .bbclass and configuration files. This variable is analogous to the PATH variable."
BBINCLUDELOGS[doc] = "Variable that controls how BitBake displays logs on build failure."
BBINCLUDELOGS_LINES[doc] = "Amount of log lines printed on failure."
BBLAYERS[doc] = "Lists the layers to enable during the build. This variable is defined in the bblayers.conf configuration file."
BBLAYERS_NON_REMOVABLE[doc] = "Lists core layers that cannot be removed from the bblayers.conf file."
BP[doc] = "The base recipe name and version but without any special recipe name suffix (i.e. -native, lib64-, and so forth). BP is comprised of ${BPN}-${PV}"
BPN[doc] = "The bare name of the recipe. This variable is a version of the PN variable but removes common suffixes and prefixes."
BUILD_ARCH[doc] = "The name of the building architecture. E.g. i686."
BUILD_OS[doc] = "The operating system (in lower case) of the building architecture. E.g linux."
BUILDDIR[doc] = "Points to the location of the Build Directory."

#C

CACHE[doc]  = "The directory holding the cache of the metadata."
CFLAGS[doc] = "Flags passed to the C compiler for the target system. This variable evaluates to the same as TARGET_CFLAGS."
COMBINED_FEATURES[doc] = "A set of features common between MACHINE_FEATURES and DISTRO_FEATURES."
COMPATIBLE_HOST[doc] = "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."
COMPATIBLE_MACHINE[doc] = "A regular expression that resolves to one or more target machines with which a recipe is compatible."
CONFFILES[doc] = "Identifies editable or configurable files that are part of a package."
CONFIG_SITE[doc] = "A list of files that contains autoconf test results relevant to the current build. This variable is used by the Autotools utilities when running configure."
CORE_IMAGE_EXTRA_INSTALL[doc] = "Specifies the list of packages to be added to the image. You should only set this variable in the conf/local.conf file in the Build Directory."
CVSDIR[doc] = "The directory where cvs checkouts will be stored in."

#D

D[doc] = "The destination directory."
DATE[doc] = "The date the build was started YMD."
DATETIME[doc] = "The date and time the build was started at."
DEBUG_BUILD[doc] = "Specifies to build packages with debugging information. This influences the value of the SELECTED_OPTIMIZATION variable."
DEBUG_OPTIMIZATION[doc] = "The options to pass in TARGET_CFLAGS and CFLAGS when compiling a system for debugging. This variable defaults to '-O -fno-omit-frame-pointer -g'."
DEFAULT_PREFERENCE[doc] = "Specifies a weak bias for recipe selection priority."
DEPENDS[doc] = "Lists a recipe's build-time dependencies (i.e. other recipe files)."
DESCRIPTION[doc] = "The package description used by package managers. If not set, DESCRIPTION takes the value of the SUMMARY variable."
DESTDIR[doc] = "The destination directory."
DISTRO[doc] = "The short name of the distribution. If the variable is blank, meta/conf/distro/defaultsetup.conf will be used."
DISTRO_EXTRA_RDEPENDS[doc] = "Specifies a list of distro-specific packages to add to all images. The variable only applies to the images that include packagegroup-base."
DISTRO_EXTRA_RRECOMMENDS[doc] = "Specifies a list of distro-specific packages to add to all images if the packages exist. The list of packages are automatically installed but you can remove them."
DISTRO_FEATURES[doc] = "The features enabled for the distribution."
DISTRO_FEATURES_BACKFILL[doc] = "Features to be added to DISTRO_FEATURES if not also present in DISTRO_FEATURES_BACKFILL_CONSIDERED. This variable is set in the meta/conf/bitbake.conf file and it is not intended to be user-configurable."
DISTRO_FEATURES_BACKFILL_CONSIDERED[doc] = "Features from DISTRO_FEATURES_BACKFILL that should not be backfilled (i.e. added to DISTRO_FEATURES) during the build."
DISTRO_NAME[doc] = "The long name of the distribution."
DISTRO_PN_ALIAS[doc] = "Alias names used for the recipe in various Linux distributions."
DISTRO_VERSION[doc] = "The version of the distribution."
DISTROOVERRIDES[doc] = "This variable lists overrides specific to the current distribution. By default, the variable list includes the value of the DISTRO variable."
DL_DIR[doc] = "The central download directory used by the build process to store downloads. By default, the directory is 'downloads' in the Build Directory."

#E

ENABLE_BINARY_LOCALE_GENERATION[doc] = "Variable that controls which locales for eglibc are generated during the build (useful if the target device has 64Mbytes of RAM or less)."
EXTENDPE[doc] = "Used with file and pathnames to create a prefix for a recipe's version based on the recipe's PE value. If PE is set and greater than zero for a recipe, EXTENDPE becomes that value."
EXTRA_IMAGE_FEATURES[doc] = "The list of additional features to include in an image. Configure this variable in the conf/local.conf file in the Build Directory."
EXTRA_IMAGEDEPENDS[doc] = "A list of recipes to build that do not provide packages for installing into the root filesystem. Use this variable to list recipes that are required to build the final image, but not needed in the root filesystem."
EXTRA_OECMAKE[doc] = "Additional cmake options."
EXTRA_OECONF[doc] = "Additional configure script options."
EXTRA_OEMAKE[doc] = "Additional GNU make options."

#F

FEED_DEPLOYDIR_BASE_URI[doc] = "Allow to serve ipk deploy dir as an adhoc feed (bogofeed). Set to base URL of the dir as exported by HTTP. Set of adhoc feed configs will be generated in image."
FILES[doc] = "The list of directories or files that are placed in packages."
FILESEXTRAPATHS[doc] = "Extends the search path the OpenEmbedded build system uses when looking for files and patches as it processes recipes and append files."
FILESPATH[doc] = "The default set of directories the OpenEmbedded build system uses when searching for patches and files. It is defined in the base.bbclass class found in meta/classes in the Source Directory. Do not hand-edit the FILESPATH variable."
FILESYSTEM_PERMS_TABLES[doc] = "Allows you to define your own file permissions settings table as part of your configuration for the packaging process."
FULL_OPTIMIZATION[doc]= "The options to pass in TARGET_CFLAGS and CFLAGS when compiling an optimized system. This variable defaults to '-fexpensive-optimizations -fomit-frame-pointer -frename-registers -O2'."

#G

GITDIR[doc] = "The directory where git clones will be stored."
GROUP_dependencies[doc] = "The keys in this group influence the dependency handling of BitBake and the resulting packages."
GROUP_fetcher[doc] = "The key highly influence the fetcher implementations."
GROUP_locale[doc] = "Locale generation of the GNU libc implementation."
GROUP_packaging[doc] = "The keys in this group influence the package building process. They influence which packages will be generated and which files will be present in the generated packages."

#H

HOMEPAGE[doc] = "Website where more information about the software the recipe is building can be found."
HOST_ARCH[doc] = "The name of the target architecture. Normally same as the TARGET_ARCH."
HOST_CC_ARCH[doc] = "Normally same as the TARGET_CC_ARCH."
HOST_NONSYSV[doc] = "This flag can be set to '1' if the host system is not SysV compatible. E.g. fakeroot-native will be build with tcp as IPC implementation."
HOST_OS[doc] = "The name of the target operating system. Normally the same as the TARGET_OS."
HOST_PREFIX[doc] = "Normally same as the TARGET_PREFIX."
HOST_SYS[doc] = "Specifies the system, including the architecture and the operating system, for with the build is occurring in the context of the current recipe."
HOST_VENDOR[doc] = "The name of the vendor. Normally same as the TARGET_VENDOR."

#I

IMAGE_FEATURES[doc] = "The primary list of features to include in an image. Configure this variable in an image recipe."
IMAGE_FSTYPES[doc] = "Formats of root filesystem images that you want to have created."
IMAGE_INSTALL[doc] = "Specifies the packages to install into an image. Image recipes set IMAGE_INSTALL to specify the packages to install into an image through image.bbclass."
IMAGE_LINGUAS[doc] = "Specifies the list of locales to install into the image during the root filesystem construction process."
IMAGE_OVERHEAD_FACTOR[doc] = "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 IMAGE_ROOTFS_SIZE and IMAGE_ROOTFS_EXTRA_SPACE."
IMAGE_ROOTFS_EXTRA_SPACE[doc] = "Defines additional free disk space created in the image in Kbytes. By default, this variable is set to '0'."
IMAGE_ROOTFS_SIZE[doc] = "Defines the size in Kbytes for the generated image."
INC_PR[doc] = "Helps define the recipe revision for recipes that share a common include file."
INHIBIT_PACKAGE_STRIP[doc] = "If set to "1", causes the build to not strip binaries in resulting packages."
INHERIT[doc] = "Causes the named class to be inherited at this point during parsing. The variable is only valid in configuration files."
INITSCRIPT_PACKAGES[doc] = "A list of the packages that contain initscripts. This variable is used in recipes when using update-rc.d.bbclass. The variable is optional and defaults to the PN variable."
INITSCRIPT_NAME[doc] = "The filename of the initscript as installed to ${etcdir}/init.d. The variable is mandatory and is used in recipes when using update-rc.d.bbclass."
INITSCRIPT_PARAMS[doc] = "Specifies the options to pass to update-rc.d. The variable is mandatory and is used in recipes when using update-rc.d.bbclass."
INSANE_SKIP[doc] = "Specifies the QA checks to skip for a specific package within a recipe."
IPK_FEED_URIS[doc] = "List of ipkg feed records to put into generated image."

#K

KARCH[doc] = "Defines the kernel architecture used when assembling the configuration. You define the KARCH variable in the BSP Descriptions."
KBRANCH[doc] = "A regular expression used by the build process to explicitly identify the kernel branch that is validated, patched and configured during a build."
KBRANCH_DEFAULT[doc] = "Defines the Linux kernel source repository's default branch used to build the Linux kernel. Unless you specify otherwise, initializes to 'master'."
KERNEL_EXTRA_ARGS[doc] = "Specifies additional make command-line arguments the OpenEmbedded build system passes on when compiling the kernel."
KERNEL_FEATURES[doc] = "Includes additional metadata from the Yocto Project kernel Git repository. The metadata you add through this variable includes config fragments and features descriptions."
KERNEL_IMAGETYPE[doc] = "The type of kernel to build for a device, usually set by the machine configuration files and defaults to 'zImage'."
KERNEL_PATH[doc] = "The location of the kernel sources. This variable is set to the value of the STAGING_KERNEL_DIR within the module.bbclass class."
KERNEL_SRC[doc] = "The location of the kernel sources. This variable is set to the value of the STAGING_KERNEL_DIR within the module.bbclass class."
KFEATURE_DESCRIPTION[doc] = "Provides a short description of a configuration fragment. You use this variable in the .scc file that describes a configuration fragment file."
KMACHINE[doc] = "The machine as known by the kernel."
KTYPE[doc] = "Defines the kernel type to be used in assembling the configuration."

#L

LAYERDEPENDS[doc] = "Lists the layers that this recipe depends upon, separated by spaces. This variable is used in the conf/layer.conf file and must be suffixed with the name of the specific layer."
LAYERDIR[doc] = "When used inside the layer.conf configuration file, this variable provides the path of the current layer."
LAYERVERSION[doc] = "Optionally specifies the version of a layer as a single number. This variable is used in the conf/layer.conf file and must be suffixed with the name of the specific layer."
LIC_FILES_CHKSUM[doc] = "Checksums of the license text in the recipe source code."
LICENSE[doc] = "The list of source licenses for the recipe."
LICENSE_PATH[doc] = "Path to additional licenses used during the build."
LINUX_KERNEL_TYPE[doc] = "Defines the kernel type to be used in assembling the configuration."
LINUX_VERSION[doc] = "The Linux version from kernel.org on which the Linux kernel image being built using the OpenEmbedded build system is based. You define this variable in the kernel recipe."
LINUX_VERSION_EXTENSION[doc] = "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."
LOG_DIR[doc] = "Specifies the directory to which the OpenEmbedded build system writes overall log files. The default directory is ${TMPDIR}/log"

#M

MACHINE[doc] = "Specifies the target device for which the image is built. You define MACHINE in the conf/local.conf file in the Build Directory."
MACHINE_ESSENTIAL_EXTRA_RDEPENDS[doc] = "A list of required machine-specific packages to install as part of the image being built. Because this is a 'machine essential' variable, the list of packages are essential for the machine to boot."
MACHINE_ESSENTIAL_EXTRA_RRECOMMENDS[doc] = "A list of recommended machine-specific packages to install as part of the image being built. Because this is a 'machine essential' variable, the list of packages are essential for the machine to boot."
MACHINE_EXTRA_RDEPENDS[doc] = "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."
MACHINE_EXTRA_RRECOMMENDS[doc] = "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."
MACHINE_FEATURES[doc] = "Specifies the list of hardware features the MACHINE supports."
MACHINE_FEATURES_BACKFILL[doc] = "Features to be added to MACHINE_FEATURES if not also present in MACHINE_FEATURES_BACKFILL_CONSIDERED. This variable is set in the meta/conf/bitbake.conf file and is not intended to be user-configurable."
MACHINE_FEATURES_BACKFILL_CONSIDERED[doc] = "Features from MACHINE_FEATURES_BACKFILL that should not be backfilled (i.e. added to MACHINE_FEATURES) during the build."
MACHINEOVERRIDES[doc] = "Lists overrides specific to the current machine. By default, this list includes the value of MACHINE."
MAINTAINER[doc] = "The email address of the distribution maintainer."
MIRRORS[doc] = "Specifies additional paths from which the OpenEmbedded build system gets source code."
MLPREFIX[doc] = "Specifies a prefix has been added to PN to create a special version of a recipe or package, such as a Multilib version."
MODULE_TARBALL_DEPLOY[doc] = "Controls creation of the modules-*.tgz file. Set this variable to "0" to disable creation of this file, which contains all of the kernel modules resulting from a kernel build."
MULTIMACH_TARGET_SYS[doc] = "Separates files for different machines such that you can build for multiple target machines using the same output directories."

BAD_RECOMMENDATIONS[doc] = "List of packages to not install if recommended.  These will still be installed if required."
NO_RECOMMENDATIONS[doc] = "When set to 1, no recommended packages will be installed.  Note: some recommended packages may be required for certain system functionality, such as kernel-modules.  It is up to the user to add packages to IMAGE_INSTALL as needed."

IMAGE_INSTALL[doc] = "Used by an image recipe to list the packages to be installed.  See PACKAGE_INSTALL."

PACKAGE_EXCLUDE[doc] = "Packages to exclude from the installation, if required an error will be generated."
PACKAGE_INSTALL[doc] = "Generally not user defined.  List of the packages to be installed into the image, uses IMAGE_INSTALL as part of the list."
PACKAGE_INSTALL_ATTEMPTONLY[doc] = "Generally not user defined.  List of packages that will be attempted to be installed, but no error will generate if any of them fail to install."

#N

NATIVELSBSTRING[doc] = "A string identifying the host distribution."

#O

OE_TERMINAL[doc] = "Controls how the OpenEmbedded build system spawns interactive terminals on the host development system."

#P

P[doc] = "The recipe name and version. P is comprised of ${PN}-${PV}"
PACKAGE_ARCH[doc] = "The architecture of the resulting package or packages."
PACKAGE_ARCHS[doc] = "A list of architectures compatible with the given target in order of priority."
PACKAGE_BEFORE_PN[doc] = "Enables easily adding packages to PACKAGES before ${PN} so that the packages can pick up files that would normally be included in the default package."
PACKAGE_CLASSES[doc] = "This variable specifies the package manager to use when packaging data. It is set in the conf/local.conf file in the Build Directory."
PACKAGE_EXTRA_ARCHS[doc] = "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."
PACKAGECONFIG[doc] = "This variable provides a means of enabling or disabling features of a recipe on a per-recipe basis."
PACKAGES[doc] = "The list of packages to be created from the recipe."
PACKAGES_DYNAMIC[doc] = "A promise that your recipe satisfies runtime dependencies for optional modules that are found in other recipes."
PALMTOP_USE_MULTITHREADED_QT[doc] = "Set to yes, if you want to build qt apps with CONFIG+=thread"
PARALLEL_MAKE[doc] = "Specifies extra options that are passed to the make command during the compile tasks. This variable is usually in the form -j 4, where the number represents the maximum number of parallel threads make can run."
PE[doc] = "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."
PF[doc] = "Specifies the recipe or package name and includes all version and revision numbers. This variable is comprised of ${PN}-${EXTENDPE}${PV}-${PR}"
PN[doc] = "PN refers to a recipe name in the context of a file used by the OpenEmbedded build system as input to create a package. It refers to a package name in the context of a file created or produced by the OpenEmbedded build system."
PR[doc] = "The revision of the recipe. The default value for this variable is 'r0'."
PREMIRRORS[doc] = "Specifies additional paths from which the OpenEmbedded build system gets source code."
PRINC[doc] = "Causes the PR variable of .bbappend files to dynamically increment. This increment minimizes the impact of layer ordering. This variable defaults to '0'."
PRIORITY[doc] = "Importance of package, the default value is 'optional', other standard values are 'required', 'standard' and 'extra'."
PROVIDES[doc] = "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 DEPENDS)."
PREFERRED_PROVIDER[doc] = "If multiple recipes provide an item, this variable determines which recipe should be given preference."
PREFERRED_VERSION[doc] = "If there are multiple versions of recipes available, this variable determines which recipe should be given preference."
PV[doc] = "The version of the recipe. The version is normally extracted from the recipe filename."

#R

RCONFLICTS[doc] = "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."
RDEPENDS[doc] = "Lists a package's runtime dependencies (i.e. other packages) that must be installed for the package to be built. They must be the names of other packages as listed in the PACKAGES variable, not recipe names (PN)."
RM_WORK_EXCLUDE[doc] = "With rm_work enabled, this variable specifies a list of packages whose work directories should not be removed."
RPROVIDES[doc] = "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."
RRECOMMENDS[doc] = "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."
RREPLACES[doc] = "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."
RSUGGESTS[doc] = "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."

#S

S[doc] = "The location in the Build Directory where unpacked package source code resides."
SANITY_TESTED_DISTROS[doc] = "A list of the host distribution identifiers that the build system has been tested against."
SDKIMAGE_FEATURES[doc] = "Equivalent to IMAGE_FEATURES. However, this variable applies to the SDK generated from an image using the command '$ bitbake -c populate_sdk imagename'."
SECTION[doc] = "The section in which packages should be categorized. Package management utilities can make use of this variable."
SELECTED_OPTIMIZATION[doc] = "The variable takes the value of FULL_OPTIMIZATION unless DEBUG_BUILD = "1". In this case the value of DEBUG_OPTIMIZATION is used."
SERIAL_CONSOLE[doc] = "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 getty is started on that port so remote login is possible."
SIGGEN_EXCLUDERECIPES_ABISAFE[doc] = "A list of recipes that are completely stable and will never change."
SIGGEN_EXCLUDE_SAFE_RECIPE_DEPS[doc] = "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."
SITEINFO_ENDIANNESS[doc] = "Specifies the endian byte order of the target system. The value should be either 'le' for 'little-endian' or 'be' for 'big-endian'."
SITEINFO_BITS[doc] = "Specifies the number of bits for the target system CPU. The value should be either '32' or '64'."
SOC_FAMILY[doc] = "Groups together machines based upon the same family of SOC (System On Chip). You typically set this variable in a common .inc file that you include in the configuration files of all the machines."
SOURCE_MIRROR_FETCH[doc] = "Switch marking build as source fetcher. Used to skip COMPATIBLE_* checking."
SOURCE_MIRROR_URL[doc] = "URL to source mirror which will be used before fetching from original SRC_URI."
SPECIAL_PKGSUFFIX[doc] = "A list of prefixes for PN 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 BPN variable."
SRC_URI[doc] = "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."
SRC_URI_OVERRIDES_PACKAGE_ARCH[doc] = "By default, the OpenEmbedded build system automatically detects whether SRC_URI contains files that are machine-specific. If so, the build system automatically changes PACKAGE_ARCH. Setting this variable to '0' disables this behavior."
SRCDATE[doc] = "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)."
SRCPV[doc] = "Returns the version string of the current package. This string is used to help define the value of PV."
SRCREV[doc] = "The revision of the source code used to build the package. This variable applies to Subversion, Git, Mercurial and Bazaar only."
SSTATE_DIR[doc] = "The directory for the shared state cache."
SSTATE_MIRRORS[doc] = "Configures the OpenEmbedded build system to search other mirror locations for prebuilt cache data objects before building out the data. You can specify a filesystem directory or a remote URL such as HTTP or FTP."
STAGING_KERNEL_DIR[doc] = "The directory with kernel headers that are required to build out-of-tree modules."
STAMP[doc] = "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."
SUMMARY[doc] = "The short (72 characters or less) summary of the binary package for packaging systems such as opkg, rpm or dpkg. By default, SUMMARY is used to define the DESCRIPTION variable if DESCRIPTION is not set in the recipe."
SVNDIR[doc] = "The directory where subversion checkouts will be stored."
SYSROOT_PREPROCESS_FUNCS[doc] = "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."
SYSVINIT_ENABLED_GETTYS[doc] = "Specify which VTs should be running a getty, the default is 1."

#T

T[doc] = "This variable points to a directory were BitBake places temporary files, which consist mostly of task logs and scripts, when building a particular recipe."
TARGET_ARCH[doc] = "The architecture of the device being built. The OpenEmbedded build system supports the following architectures: arm, mips, ppc, x86, x86-64."
TARGET_CFLAGS[doc] = "Flags passed to the C compiler for the target system. This variable evaluates to the same as CFLAGS."
TARGET_FPU[doc] = "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."
TARGET_OS[doc] = "Specifies the target's operating system."
TARGET_PREFIX[doc] = "The prefix for the cross compile toolchain. E.g arm-linux- ."
TARGET_SYS[doc] = "The target system is composed out of TARGET_ARCH,TARGET_VENDOR and TARGET_OS."
TCLIBC[doc] = "Specifies which variant of the GNU standard C library (libc) to use during the build process. You can select eglibc or uclibc."
TCMODE[doc] = "The toolchain selector. It selects the external toolchain built using the OpenEmbedded build system or a few supported combinations of the upstream GCC or CodeSourcery Labs toolchain."
TIME[doc] = "The time the build was started HMS"
TMPDIR[doc] = "This variable is the temporary directory the OpenEmbedded build system uses when it does its work building images. By default, the TMPDIR variable is named tmp within the Build Directory."
TOPDIR[doc] = "This variable is the Build Directory. BitBake automatically sets this variable. The OpenEmbedded build system uses the Build Directory when building images."
TUNEABI[doc] = "An underlying ABI used by a particular tuning in a given toolchain layer. This feature allows providers using prebuilt libraries to check compatibility of a tuning against their selection of libraries."
TUNEABI_OVERRIDE[doc] = "If set, ignores TUNEABI_WHITELIST."
TUNEABI_WHITELIST[doc] = "A whitelist of permissible TUNEABI values; if unset, all are allowed."
TUNECONFLICTS[doc] = "List of conflicting features for a given feature."
TUNEVALID[doc] = "Descriptions of valid tuning features, stored as flags."

#W

WORKDIR[doc] = "The pathname of the working directory in which the OpenEmbedded build system builds a recipe. This directory is located within the TMPDIR directory structure and changes as different packages are built."