Table of Contents
This chapter lists common variables used in the OpenEmbedded build system and gives an overview of their function and contents.
A B C D E F H I K L M O P R S T W
Specifies if an output package should still be produced if it is empty.
By default, BitBake does not produce empty packages.
This default behavior can cause issues when there is an
RDEPENDS
or
some other runtime hard-requirement on the existence of the package.
Like all package-controlling variables, you must always use them in conjunction with a package name override. Here is an example:
ALLOW_EMPTY_${PN} = "1"
The email address used to contact the original author or authors in order to send patches, forward bugs, etc.
When SRCREV
is set to the value of this variable, it specifies that the latest
source revision in the repository should be used. Here is an example:
SRCREV = "${AUTOREV}"
The Build Directory.
The OpenEmbedded build system places generated objects into the Build Directory
during a recipe's build process.
By default, this directory is the same as the S
directory:
B = ${WORKDIR}/${BPN}-{PV}/
You can separate the (S
) directory and the directory pointed to
by the B
variable.
Most autotools-based recipes support separating these directories.
The build system defaults to using separate directories for gcc
and some kernel recipes.
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.
Monitors disk space and available inodes during the build and allows you to control the build based on these parameters.
Disk space monitoring is disabled by default.
To enable monitoring, add the BB_DISKMON_DIRS
variable to your conf/local.conf
file found in the
Build Directory.
Use the following form:
BB_DISKMON_DIRS = "<action>,<dir>,<threshold> [...]" where: <action> is: ABORT: Immediately abort the build when a threshold is broken. STOPTASKS: Stop the build after the currently executing tasks have finished when a threshold is broken. WARN: Issue a warning but continue the build when a threshold is broken. Subsequent warnings are issued as defined by the BB_DISKMON_WARNINTERVAL variable, which must be defined in the conf/local.conf file. <dir> is: Any directory you choose. You can specify one or more directories to monitor by separating the groupings with a space. If two directories are on the same device, only the first directory is monitored. <threshold> is: Either the minimum available disk space, the minimum number of free inodes, or both. You must specify at least one. To omit one or the other, simply omit the value. Specify the threshold using G, M, K for Gbytes, Mbytes, and Kbytes, respectively. If you do not specify G, M, or K, Kbytes is assumed by default. Do not use GB, MB, or KB.
Here are some examples:
BB_DISKMON_DIRS = "ABORT,${TMPDIR},1G,100K WARN,${SSTATE_DIR},1G,100K" BB_DISKMON_DIRS = "STOPTASKS,${TMPDIR},1G" BB_DISKMON_DIRS = "ABORT,${TMPDIR},,100K"
The first example works only if you also provide
the BB_DISKMON_WARNINTERVAL
variable
in the conf/local.conf
.
This example causes the build system to immediately
abort when either the disk space in ${TMPDIR}
drops
below 1 Gbyte or the available free inodes drops below
100 Kbytes.
Because two directories are provided with the variable, the
build system also issue a
warning when the disk space in the
${SSTATE_DIR}
directory drops
below 1 Gbyte or the number of free inodes drops
below 100 Kbytes.
Subsequent warnings are issued during intervals as
defined by the BB_DISKMON_WARNINTERVAL
variable.
The second example stops the build after all currently
executing tasks complete when the minimum disk space
in the ${TMPDIR}
directory drops
below 1 Gbyte.
No disk monitoring occurs for the free inodes in this case.
The final example immediately aborts the build when the
number of free inodes in the ${TMPDIR}
directory
drops below 100 Kbytes.
No disk space monitoring for the directory itself occurs
in this case.
Defines the disk space and free inode warning intervals.
To set these intervals, define the variable in your
conf/local.conf
file in the
Build Directory.
If you are going to use the
BB_DISKMON_WARNINTERVAL
variable, you must
also use the
BB_DISKMON_DIRS
variable
and define its action as "WARN".
During the build, subsequent warnings are issued each time
disk space or number of free inodes further reduces by
the respective interval.
If you do not provide a BB_DISKMON_WARNINTERVAL
variable and you do use BB_DISKMON_DIRS
with
the "WARN" action, the disk monitoring interval defaults to
the following:
BB_DISKMON_WARNINTERVAL = "50M,5K"
When specifying the variable in your configuration file, use the following form:
BB_DISKMON_WARNINTERVAL = "<disk_space_interval>,<disk_inode_interval>" where: <disk_space_interval> is: An interval of memory expressed in either G, M, or K for Gbytes, Mbytes, or Kbytes, respectively. You cannot use GB, MB, or KB. <disk_inode_interval> is: An interval of free inodes expressed in either G, M, or K for Gbytes, Mbytes, or Kbytes, respectively. You cannot use GB, MB, or KB.
Here is an example:
BB_DISKMON_DIRS = "WARN,${SSTATE_DIR},1G,100K" BB_DISKMON_WARNINTERVAL = "50M,5K"
These variables cause the OpenEmbedded build system to
issue subsequent warnings each time the available
disk space further reduces by 50 Mbytes or the number
of free inodes further reduces by 5 Kbytes in the
${SSTATE_DIR}
directory.
Subsequent warnings based on the interval occur each time
a respective interval is reached beyond the intial warning
(i.e. 1 Gbytes and 100 Kbytes).
Allows you to extend a recipe so that it builds variants of the software.
Common variants for recipes exist such as "natives" like quilt-native
,
which is a copy of quilt built to run on the build system;
"crosses" such as gcc-cross
,
which is a compiler built to run on the build machine but produces binaries
that run on the target MACHINE
;
"nativesdk", which targets the SDK machine instead of MACHINE
;
and "mulitlibs" in the form "multilib:<multilib_name>
".
To build a different variant of the recipe with a minimal amount of code, it usually is as simple as adding the following to your recipe:
BBCLASSEXTEND =+ "native nativesdk" BBCLASSEXTEND =+ "multilib:<multilib_name>"
Prevents BitBake from processing recipes and recipe append files.
You can use the BBMASK
variable to "hide"
these .bb
and .bbappend
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.
The value you provide is passed to python's regular expression compiler.
For complete syntax information, see python's documentation at
http://docs.python.org/release/2.3/lib/re-syntax.html.
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
.*/meta-ti/recipes-misc/
directory:
BBMASK = ".*/meta-ti/recipes-misc/"
Use the BBMASK
variable from within the
conf/local.conf
file found
in the Build Directory.
The maximum number of tasks BitBake should run in parallel at any one time. If your host development system supports multiple cores a good rule of thumb is to set this variable to twice the number of cores.
Lists the names of configured layers.
These names are used to find the other BBFILE_*
variables.
Typically, each layer will append its name to this variable in its
conf/layer.conf
file.
Variable that expands to match files from BBFILES
in a particular layer.
This variable is used in the conf/layer.conf
file and must
be suffixed with the name of the specific layer (e.g.
BBFILE_PATTERN_emenlow
).
Assigns the priority for recipe files in each layer.
This variable is useful in situations where the same recipe appears in
more than one layer.
Setting this variable allows you to prioritize a
layer against other layers that contain the same recipe - effectively
letting you control the precedence for the multiple layers.
The precedence established through this variable stands regardless of a
recipe's version (PV
variable).
For example, a layer that has a recipe with a higher PV
value but for
which the BBFILE_PRIORITY
is set to have a lower precedence still has a
lower precedence.
A larger value for the BBFILE_PRIORITY
variable results in a higher
precedence.
For example, the value 6 has a higher precedence than the value 5.
If not specified, the BBFILE_PRIORITY
variable is set based on layer
dependencies (see the
LAYERDEPENDS
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).
bitbake-layers show_layers
to list
all configured layers along with their priorities.
List of recipe files used by BitBake to build software
Used by BitBake to locate .bbclass
and configuration files.
This variable is analogous to the PATH
variable.
Variable that controls how BitBake displays logs on build failure.
Lists the layers to enable during the build.
This variable is defined in the bblayers.conf
configuration
file in the Build Directory.
Here is an example:
BBLAYERS = " \ /home/scottrif/poky/meta \ /home/scottrif/poky/meta-yocto \ /home/scottrif/poky/meta-yocto-bsp \ /home/scottrif/poky/meta-mykernel \ "
This example enables four layers, one of which is a custom, user-defined layer
named meta-mykernel
.
The base recipe name and version but without any special
recipe name suffix (i.e. -native
, lib64-
,
and so forth).
BP
is comprised of the following:
${BPN}-${PV}
The bare name of the recipe.
This variable is a version of the PN
variable
but removes common suffixes such as "-native" and "-cross" as well
as removes common prefixes such as multilib's "lib64-" and "lib32-".
The exact list of suffixes removed is specified by the
SPECIAL_PKGSUFFIX
variable.
The exact list of prefixes removed is specified by the
MLPREFIX
variable.
Prefixes are removed for multilib and nativesdk cases.
Flags passed to C compiler for the target system.
This variable evaluates to the same as
TARGET_CFLAGS
.
A set of features common between
MACHINE_FEATURES
and DISTRO_FEATURES
.
See the glossary descriptions for these variables for more information.
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.
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 CONFFILES
variable to list the files in the
package that you wish to prevent the PMS from overwriting during this update process.
To use the CONFFILES
variable, provide a package name
override that identifies the resulting package.
Then, provide a space-separated list of files.
Here is an example:
CONFFILES_${PN} += "${sysconfdir}/file1 \ ${sysconfdir}/file2 ${sysconfdir}/file3"
A relationship exists between the CONFFILES
and
FILES
variables.
The files listed within CONFFILES
must be a subset of
the files listed within FILES
.
Because the configuration files you provide with CONFFILES
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
FILES
variable.
CONFFILES
variable,
it is good practice to use appropriate path variables.
For example, ${sysconfdir}
rather than
/etc
or ${bindir}
rather
than /usr/bin
.
You can find a list of these variables at the top of the
/meta/conf/bitbake.conf
file in the
Source Directory.
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
.
Specifies the list of packages to be added to the image.
This variable should only be set in the local.conf
configuration file found in the
Build Directory.
This variable replaces POKY_EXTRA_INSTALL
, which is no longer supported.
The destination directory.
Specifies to build packages with debugging information.
This influences the value of the
SELECTED_OPTIMIZATION
variable.
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".
Specifies the priority of recipes.
Lists a recipe's build-time dependencies (i.e. other recipe files). The system ensures that all the dependencies listed have been built and have their contents in the appropriate sysroots before the recipe's configure task is executed.
The package description used by package managers.
If not set, DESCRIPTION
takes
the value of the
SUMMARY
variable.
the destination directory.
The short name of the distribution.
This variable corresponds to a file with the
extension .conf
located in a conf/distro
directory
within the metadata that contains the distribution configuration.
The
value must not contain spaces, and is typically all lower-case.
If the variable is blank, a set of default configuration
will be used, which is specified
within meta/conf/distro/defaultsetup.conf
.
Specifies a list of distro-specific packages to add to all images.
This variable takes affect through
packagegroup-base
so the
variable only really applies to the more full-featured
images that include packagegroup-base
.
You can use this variable to keep distro policy out of
generic images.
As with all other distro variables, you set this variable
in the distro .conf
file.
Specifies a list of distro-specific packages to add to all images if the packages exist. The packages might not exist or be empty (e.g. kernel modules). The list of packages are automatically installed but can be removed by the user.
The features enabled for the distribution. For a list of features supported by the Yocto Project as shipped, see the "Distro" section.
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.
It is not intended to be user-configurable.
It is best to just reference the variable to see which distro features are
being backfilled for all distro configurations.
See the Feature backfilling section for
more information.
Features from
DISTRO_FEATURES_BACKFILL
that should not backfilled (i.e. added to
DISTRO_FEATURES
)
during the build.
See the "Feature Backfilling" section for
more information.
The long name of the distribution.
Alias names used for the recipe in various Linux distributions.
See the "Handling a Package Name Alias" section in the Yocto Project Development Manual for more information.
the version of the distribution.
The central download directory used by the build process to store downloads.
You can set this directory by defining the DL_DIR
variable in the /conf/local.conf
file.
This directory is self-maintaining and you should not have
to touch it.
By default, the directory is downloads
in the
Build Directory.
#DL_DIR ?= "${TOPDIR}/downloads"
To specify a different download directory, simply uncomment the line and provide your directory.
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
DL_DIR
and the build system looks there first
to find source tarballs.
You can safely share this directory between multiple builds on the same development machine. For additional information on how the build process gets source files when working behind a firewall or proxy server, see the "FAQ" chapter.
Variable that controls which locales for eglibc
are
to be generated during the build (useful if the target device has 64Mbytes
of RAM or less).
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 (e.g if
PE
is equal to "1" then EXTENDPE
becomes "1_").
If a recipe's PE
is not set (the default) or is equal to
zero, EXTENDPE
becomes "".
See the STAMP
variable for an example.
Allows extra packages to be added to the generated images.
You set this variable in the local.conf
configuration file.
Note that some image features are also added using the
IMAGE_FEATURES
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:
"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 valid features too, see the Images section for more details.
A list of recipes to be built that do not provide packages to be installed in the root filesystem.
Sometimes a recipe is required to build the final image but is not
needed in the root filesystem.
You can use the EXTRA_IMAGEDEPENDS
variable to
list these recipes and thus, specify the dependencies.
A typical example is a required bootloader in a machine configuration.
*DEPENDS
and *RECOMMENDS
variables.
Additional cmake
options.
Additional configure
script options.
Additional GNU make
options.
The list of directories or files that are placed in packages.
To use the FILES
variable, provide a package name
override that identifies the resulting package.
Then, provide a space-separated list of files or paths that identifies the
files you want included as part of the resulting package.
Here is an example:
FILES_${PN} += "${bindir}/mydir1/ ${bindir}/mydir2/myfile"
FILES
variable,
it is good practice to use appropriate path variables.
For example, ${sysconfdir}
rather than
/etc
or ${bindir}
rather
than /usr/bin
.
You can find a list of these variables at the top of the
/meta/conf/bitbake.conf
file in the
Source Directory.
If some of the files you provide with the FILES
variable
are editable and you know they should not be
overwritten during the package update process by the Package Management
System (PMS), you can identify these files so that the PMS will not
overwrite them.
See the CONFFILES
variable for information on how to identify these files to the PMS.
Extends the search path the OpenEmbedded build system uses when
looking for files and patches as it processes recipes.
The directories BitBake uses when it processes recipes is defined by the
FILESPATH
variable.
You can add directories to the search path by defining the
FILESEXTRAPATHS
variable.
To add paths to the search order, provide a list of directories and separate each path using a colon character as follows:
FILESEXTRAPATHS_prepend := "path_1:path_2:path_3:"
Typically, you want your directories search first.
To make sure that happens, use _prepend
and
the immediate expansion (:=
) operator as shown in the
previous example.
Finally, to maintain the integrity of the FILESPATH
variable,
you must include the appropriate beginning or ending (as needed) colon character.
The FILESEXTRAPATHS
variable is intended for use in
.bbappend
files to include any additional files provided in that layer.
You typically accomplish this with the following:
FILESEXTRAPATHS_prepend := "${THISDIR}/${PN}:"
The default set of directories the OpenEmbedded build system uses
when searching for patches and files.
During the build process, BitBake searches each directory in
FILESPATH
in the specified order when looking for
files and patches specified by each file://
URI in a recipe.
The default value for the FILESPATH
variable is defined
in the base.bbclass
class found in
meta/classes
in the
Source Directory:
FILESPATH = "${@base_set_filespath([ "${FILE_DIRNAME}/${PF}", \ "${FILE_DIRNAME}/${P}", "${FILE_DIRNAME}/${PN}", \ "${FILE_DIRNAME}/${BP}", "${FILE_DIRNAME}/${BPN}", \ "${FILE_DIRNAME}/files", "${FILE_DIRNAME}" ], d)}"
Do not hand-edit the FILESPATH
variable.
If you want to extend the set of pathnames that BitBake uses when searching for
files and patches, use the
FILESEXTRAPATHS
variable.
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.
By default, the OpenEmbedded build system uses the fs-perms.txt
, which
is located in the meta/files
folder in the
Source Directory.
If you create your own file permissions setting table, you should place it in your
layer or the distros layer.
You define the FILESYSTEM_PERMS_TABLES
variable in the
conf/local.conf
file, which is found in the
Build Directory, to
point to your custom fs-perms.txt
.
You can specify more than a single file permissions setting table.
The paths you specify to these files must be defined within the
BBPATH
variable.
For guidance on how to create your own file permissions settings table file,
examine the existing fs-perms.txt
.
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".
The list of features to include in an image.
Typically, you configure this variable in an image recipe.
Note that you can also add extra features to the image by using the
EXTRA_IMAGE_FEATURES
variable.
See the "Images" section for the
full list of features that can be included in images built by the
OpenEmbedded build system.
Formats of root filesystem images that you want to have created.
Specifies the packages to install into an image.
The IMAGE_INSTALL
variable is a mechanism for an image
recipe and you should use it with care to avoid ordering issues.
Image recipes set IMAGE_INSTALL
to specify the
packages to install into an image through image.bbclass
.
Additionally, "helper" classes exist, such as core-image.bbclass
,
that can take
IMAGE_FEATURES
lists
and turn these into auto-generated entries in
IMAGE_INSTALL
in addition to its default contents.
Using IMAGE_INSTALL
with the +=
operator from the /conf/local.conf
file or from within
an image recipe is not recommended as it can cause ordering issues.
Since core-image.bbclass
sets IMAGE_INSTALL
to a default value using the ?=
operator, using a
+=
operation against IMAGE_INSTALL
will result in unexpected behavior when used in
/conf/local.conf
.
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 +=
operator to work.
When you use this variable, it is best to use it as follows:
IMAGE_INSTALL_append = " package-name"
Be sure to include the space between the quotation character and the start of the package name.
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
.
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 IMAGE_ROOTFS_SIZE
for information on how the build system determines the overall image size.
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:
IMAGE_OVERHEAD_FACTOR = "1.5"
Alternatively, you can ensure a specific amount of free disk space is added
to the image by using
IMAGE_ROOTFS_EXTRA_SPACE
the variable.
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
IMAGE_ROOTFS_SIZE
.
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:
IMAGE_ROOTFS_EXTRA_SPACE = "5242880"
Defines the size in Kbytes for the generated image. The OpenEmbedded build system determines the final size for the generated image using an algorithm that takes into account the initial disk space used for the generated image, a requested size for the image, and requested additional free disk space to be added to the image. Programatically, the build system determines the final size of the generated image as follows:
if (image-du * overhead) < 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
Helps define the recipe revision for recipes that share
a common include
file.
You can think of this variable as part of the recipe revision
as set from within an include file.
Suppose, for example, you have a set of recipes that
are used across several projects.
And, within each of those recipes the revision
(its PR
value) is set accordingly.
In this case, when the revision of those recipes changes
the burden is on you to find all those recipes and
be sure that they get changed to reflect the updated
version of the recipe.
In this scenario, it can get complicated when recipes
used in many places and that provide common functionality
are upgraded to a new revision.
A more efficient way of dealing with this situation is
to set the INC_PR
variable inside
the include
files that the recipes
share and then expand the INC_PR
variable within the recipes to help
define the recipe revision.
The following provides an example that shows how to use
the INC_PR
variable
given a common include
file that
defines the variable.
Once the variable is defined in the
include
file, you can use the
variable to set the PR
values in
each recipe.
You will notice that when you set a recipe's
PR
you can provide more granular
revisioning by appending values to the
INC_PR
variable:
recipes-graphics/xorg-font/xorg-font-common.inc:INC_PR = "r2" recipes-graphics/xorg-font/encodings_1.0.4.bb:PR = "${INC_PR}.1" recipes-graphics/xorg-font/font-util_1.3.0.bb:PR = "${INC_PR}.0" recipes-graphics/xorg-font/font-alias_1.0.3.bb:PR = "${INC_PR}.3"
The first line of the example establishes the baseline
revision to be used for all recipes that use the
include
file.
The remaining lines in the example are from individual
recipes and show how the PR
value
is set.
Causes the build to not strip binaries in resulting packages.
Causes the named class to be inherited at this point during parsing. The variable is only valid in configuration files.
A list of the packages that contain initscripts.
If multiple packages are specified, you need to append the package name
to the other INITSCRIPT_*
as an override.
This variable is used in recipes when using update-rc.d.bbclass
.
The variable is optional and defaults to the PN
variable.
The filename of the initscript (as installed to ${etcdir}/init.d)
.
This variable is used in recipes when using update-rc.d.bbclass
.
The variable is Mandatory.
Specifies the options to pass to update-rc.d
.
An example is start 99 5 2 . stop 20 0 1 6 .
, which gives the script a
runlevel of 99, starts the script in initlevels 2 and 5, and
stops the script in levels 0, 1 and 6.
The variable is mandatory and is used in recipes when using
update-rc.d.bbclass
.
A regular expression used by the build process to explicitly identify the kernel
branch that is validated, patched and configured during a build.
The KBRANCH
variable is optional.
You can use it to trigger checks to ensure the exact kernel branch you want is
being used by the build process.
Values for this variable are set in the kernel's recipe file and the kernel's
append file.
For example, if you are using the Yocto Project kernel that is based on the
Linux 3.4 kernel, the kernel recipe file is the
meta/recipes-kernel/linux/linux-yocto_3.4.bb
file.
Following is the default value for KBRANCH
and the default
override for the architectures the Yocto Project supports:
KBRANCH_DEFAULT = "standard/base" KBRANCH = "${KBRANCH_DEFAULT}"
This branch exists in the linux-yocto-3.4
kernel Git
repository http://git.yoctoproject.org/cgit.cgi/linux-yocto-3.4/refs/heads.
This variable is also used from the kernel's append file to identify the kernel
branch specific to a particular machine or target hardware.
The kernel's append file is located in the BSP layer for a given machine.
For example, the kernel append file for the Crown Bay BSP is in the
meta-intel
Git repository and is named
meta-crownbay/recipes-kernel/linux/linux-yocto_3.4.bbappend
.
Here are the related statements from the append file:
COMPATIBLE_MACHINE_crownbay = "crownbay" KMACHINE_crownbay = "crownbay" KBRANCH_crownbay = "standard/crownbay" COMPATIBLE_MACHINE_crownbay-noemgd = "crownbay-noemgd" KMACHINE_crownbay-noemgd = "crownbay" KBRANCH_crownbay-noemgd = "standard/crownbay"
The KBRANCH_*
statements identify the kernel branch to
use when building for the Crown Bay BSP.
In this case there are two identical statements: one for each type of
Crown Bay machine.
Includes additional metadata from the Yocto Project kernel Git repository.
In the OpenEmbedded build system, the default Board Support Packages (BSPs)
metadata is provided through
the KMACHINE
and KBRANCH
variables.
You can use the KERNEL_FEATURES
variable to further
add metadata for all BSPs.
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 KERNEL_FEATURES
variable
for a specific machine.
In this way, you can provide validated, but optional, sets of kernel
configurations and features.
For example, the following adds netfilter
to all
the Yocto Project kernels and adds sound support to the qemux86
machine:
# Add netfilter to all linux-yocto kernels KERNEL_FEATURES="features/netfilter" # Add sound support to the qemux86 machine KERNEL_FEATURES_append_qemux86=" cfg/sound"
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 make
as the target to
build.
The machine as known by the kernel.
Sometimes the machine name used by the kernel does not match the machine name
used by the OpenEmbedded build system.
For example, the machine name that the OpenEmbedded build system understands as
qemuarm
goes by a different name in the Linux Yocto kernel.
The kernel understands that machine as arm_versatile926ejs
.
For cases like these, the KMACHINE
variable maps the
kernel machine name to the OpenEmbedded build system machine name.
Kernel machine names are initially defined in the
Yocto Linux Kernel in
the meta
branch.
From the meta
branch, look in
the meta/cfg/kernel-cache/bsp/<bsp_name>/<bsp-name>-<kernel-type>.scc
file.
For example, from the meta
branch in the
linux-yocto-3.0
kernel, the
meta/cfg/kernel-cache/bsp/cedartrail/cedartrail-standard.scc
file
has the following:
define KMACHINE cedartrail define KTYPE standard define KARCH i386 include ktypes/standard branch cedartrail include cedartrail.scc
You can see that the kernel understands the machine name for the Cedar Trail BSP as
cedartrail
.
If you look in the Cedar Trail BSP layer in the meta-intel
source
repository at meta-cedartrail/recipes-kernel/linux/linux-yocto_3.0.bbappend
,
you will find the following statements among others:
COMPATIBLE_MACHINE_cedartrail = "cedartrail" KMACHINE_cedartrail = "cedartrail" KBRANCH_cedartrail = "yocto/standard/cedartrail" KERNEL_FEATURES_append_cedartrail += "bsp/cedartrail/cedartrail-pvr-merge.scc" KERNEL_FEATURES_append_cedartrail += "cfg/efi-ext.scc" COMPATIBLE_MACHINE_cedartrail-nopvr = "cedartrail" KMACHINE_cedartrail-nopvr = "cedartrail" KBRANCH_cedartrail-nopvr = "yocto/standard/cedartrail" KERNEL_FEATURES_append_cedartrail-nopvr += " cfg/smp.scc"
The KMACHINE
statements in the kernel's append file make sure that
the OpenEmbedded build system and the Yocto Linux kernel understand the same machine
names.
This append file uses two KMACHINE
statements.
The first is not really necessary but does ensure that the machine known to the
OpenEmbedded build system as cedartrail
maps to the machine
in the kernel also known as cedartrail
:
KMACHINE_cedartrail = "cedartrail"
The second statement is a good example of why the KMACHINE
variable
is needed.
In this example, the OpenEmbedded build system uses the cedartrail-nopvr
machine name to refer to the Cedar Trail BSP that does not support the propriatory
PowerVR driver.
The kernel, however, uses the machine name cedartrail
.
Thus, the append file must map the cedartrail-nopvr
machine name to
the kernel's cedartrail
name:
KMACHINE_cedartrail-nopvr = "cedartrail"
BSPs that ship with the Yocto Project release provide all mappings between the Yocto
Project kernel machine names and the OpenEmbedded machine names.
Be sure to use the KMACHINE
if you create a BSP and the machine
name you use is different than that used in the kernel.
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 LAYERVERSION_anotherlayer
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 conf/layer.conf
file
and must be suffixed with the name of the specific layer (e.g.
LAYERDEPENDS_mylayer
).
When used inside the layer.conf
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.
Optionally specifies the version of a layer as a single number.
You can use this within LAYERDEPENDS
for another layer in order to
depend on a specific version of the layer.
This variable is used in the conf/layer.conf
file
and must be suffixed with the name of the specific layer (e.g.
LAYERVERSION_mylayer
).
Checksums of the license text in the recipe source code.
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.
This variable must be defined for all recipes (unless LICENSE
is set to "CLOSED")
For more information, see the Tracking License Changes section
The list of source licenses for the recipe. Follow these rules:
Do not use spaces within individual license names.
Separate license names using | (pipe) when there is a choice between licenses.
Separate license names using & (ampersand) when multiple licenses exist that cover different parts of the source.
You can use spaces between license names.
Here are some examples:
LICENSE = "LGPLv2.1 | GPLv3" LICENSE = "MPL-1 & LGPLv2.1" LICENSE = "GPLv2+"
The first example is from the recipes for Qt, which the user
may choose to distribute under either the LGPL version
2.1 or GPL version 3.
The second example is from Cairo where two licenses cover
different parts of the source code.
The final example is from sysstat
,
which presents a single license.
Path to additional licenses used during the build.
By default, the OpenEmbedded build system uses COMMON_LICENSE_DIR
to define the directory that holds common license text used during the build.
The LICENSE_PATH
variable allows you to extend that
location to other areas that have additional licenses:
LICENSE_PATH += "/path/to/additional/common/licenses"
Specifies the target device for which the image is built.
You define MACHINE
in the
local.conf
file found in the
Build Directory.
By default, MACHINE
is set to
"qemux86", which is an x86-based architecture machine to
be emulated using QEMU:
MACHINE ?= "qemux86"
The variable corresponds to a machine configuration file of the
same name, through which machine-specific configurations are set.
Thus, when MACHINE
is set to "qemux86" there
exists the corresponding qemux86.conf
machine
configuration file, which can be found in the
Source Directory
in meta/conf/machine
.
The list of machines supported by the Yocto Project as shipped include the following:
MACHINE ?= "qemuarm" MACHINE ?= "qemumips" MACHINE ?= "qemuppc" MACHINE ?= "qemux86" MACHINE ?= "qemux86-64" MACHINE ?= "atom-pc" MACHINE ?= "beagleboard" MACHINE ?= "mpc8315e-rdb" MACHINE ?= "routerstationpro"
The last four are Yocto Project reference hardware boards, which
are provided in the meta-yocto-bsp
layer.
MACHINE
.
A list of required machine-specific packages to install as part of
the image being built.
The build process depends on these packages being present.
Furthermore, because this is a "machine essential" variable, the list of
packages are essential for the machine to boot.
The impact of this variable affects images based on
packagegroup-core-boot
,
including the core-image-minimal
image.
This variable is similar to the
MACHINE_ESSENTIAL_EXTRA_RRECOMMENDS
variable with the exception that the image being built has a build
dependency on the variable's list of packages.
In other words, the image will not build if a file in this list is not found.
As an example, suppose the machine for which you are building requires
example-init
to be run during boot to initialize the hardware.
In this case, you would use the following in the machine's
.conf
configuration file:
MACHINE_ESSENTIAL_EXTRA_RDEPENDS += "example-init"
A list of recommended machine-specific packages to install as part of
the image being built.
The build process does not depend on these packages being present.
However, because this is a "machine essential" variable, the list of
packages are essential for the machine to boot.
The impact of this variable affects images based on
packagegroup-core-boot
,
including the core-image-minimal
image.
This variable is similar to the
MACHINE_ESSENTIAL_EXTRA_RDEPENDS
variable with the exception that the image being built does not have a build
dependency on the variable's list of packages.
In other words, the image will still build if a package in this list is not found.
Typically, this variable is used to handle essential kernel modules, whose
functionality may be selected to be built into the kernel rather than as a module,
in which case a package will not be produced.
Consider an example where you have a custom kernel where a specific touchscreen
driver is required for the machine to be usable.
However, the driver can be built as a module or
into the kernel depending on the kernel configuration.
If the driver is built as a module, you want it to be installed.
But, when the driver is built into the kernel, you still want the
build to succeed.
This variable sets up a "recommends" relationship so that in the latter case,
the build will not fail due to the missing package.
To accomplish this, assuming the package for the module was called
kernel-module-ab123
, you would use the
following in the machine's .conf
configuration
file:
MACHINE_ESSENTIAL_EXTRA_RRECOMMENDS += "kernel-module-ab123"
Some examples of these machine essentials are flash, screen, keyboard, mouse, or touchscreen drivers (depending on the machine).
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.
This variable affects all images based on
packagegroup-base
, which does not include the
core-image-minimal
or core-image-basic
images.
The variable is similar to the
MACHINE_EXTRA_RRECOMMENDS
variable with the exception that the image being built has a build
dependency on the variable's list of packages.
In other words, the image will not build if a file in this list is not found.
An example is a machine that has WiFi capability but is not essential
For the machine to boot the image.
However, if you are building a more fully-featured image, you want to enable
the WiFi.
The package containing the firmware for the WiFi hardware is always
expected to exist, so it is acceptable for the build process to depend upon
finding the package.
In this case, assuming the package for the firmware was called
wifidriver-firmware
, you would use the following in the
.conf
file for the machine:
MACHINE_EXTRA_RDEPENDS += "wifidriver-firmware"
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.
This variable affects only images based on
packagegroup-base
, which does not include the
core-image-minimal
or core-image-basic
images.
This variable is similar to the
MACHINE_EXTRA_RDEPENDS
variable with the exception that the image being built does not have a build
dependency on the variable's list of packages.
In other words, the image will build if a file in this list is not found.
An example is a machine that has WiFi capability but is not essential
For the machine to boot the image.
However, if you are building a more fully-featured image, you want to enable
WiFi.
In this case, the package containing the WiFi kernel module will not be produced
if the WiFi driver is built into the kernel, in which case you still want the
build to succeed instead of failing as a result of the package not being found.
To accomplish this, assuming the package for the module was called
kernel-module-examplewifi
, you would use the
following in the .conf
file for the machine:
MACHINE_EXTRA_RRECOMMENDS += "kernel-module-examplewifi"
Specifies the list of hardware features the
MACHINE supports.
For example, including the "bluetooth" feature causes the
bluez
bluetooth daemon to be built and
added to the image.
It also causes the connman
recipe
to look at MACHINE_FEATURES
and when it
finds "bluetooth" there it enables the bluetooth
support in ConnMan.
For a list of features supported by the Yocto Project as shipped, see the "Machine" section.
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.
It is not intended to be user-configurable.
It is best to just reference the variable to see which machine features are
being backfilled for all machine configurations.
See the Feature backfilling section for
more information.
Features from
MACHINE_FEATURES_BACKFILL
that should not be backfilled (i.e. added to
MACHINE_FEATURES
)
during the build.
See the Feature backfilling section for
more information.
The email address of the distribution maintainer.
Specifies a prefix has been added to
PN
to create a special version
of a recipe or package, such as a multilib version.
The variable is used in places where the prefix needs to be
added to or removed from a the name (e.g. the
BPN
variable).
MLPREFIX
gets set when a prefix has been
added to PN
.
Separates files for different machines such that you can build
for multiple target machines using the same output directories.
See the STAMP
variable
for an example.
Controls how the OpenEmbedded build system spawns
interactive terminals on the host development system
(e.g. using the BitBake command with the
-c devshell
command-line option).
For more information, see the
"Using a Development Shell" section
in the Yocto Project Development Manual.
You can use the following values for the
OE_TERMINAL
variable:
auto gnome xfce rxvt screen konsole none
OE_TERMINAL
The recipe name and version.
P
is comprised of the following:
${PN}-${PV}
The architecture of the resulting package or packages.
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.
This variable, which is set in the local.conf
configuration
file found in the conf
folder of the
Source 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:
PACKAGE_CLASSES ?= "package_rpm package_deb package_ipk"
For information on build performance effects as a result of the
package manager use, see
Packaging - package*.bbclass
in this manual.
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).
This variable provides a means of enabling or disabling
features of a recipe on a per-recipe basis.
The PACKAGECONFIG
variable itself specifies a space-separated list of the
features to enable.
The features themselves are specified as flags on the
PACKAGECONFIG
variable.
You can provide up to four arguments, which are separated by
commas, to determine the behavior of each feature
when it is enabled or disabled.
You can omit any argument you like but must retain the
separating commas.
The arguments specify the following:
Extra arguments
that should be added to the configure script argument list
(EXTRA_OECONF
)
if the feature is enabled.
Extra arguments
that should be added to EXTRA_OECONF
if the feature is disabled.
Additional build dependencies
(DEPENDS
)
that should be added if the feature is enabled.
Additional runtime dependencies
(RDEPENDS
)
that should be added if the feature is enabled.
Consider the following example taken from the
librsvg
recipe.
In this example the feature is croco
, which
has three arguments that determine the feature's behavior.
PACKAGECONFIG ??= "croco" PACKAGECONFIG[croco] = "--with-croco,--without-croco,libcroco"
The --with-croco
and
libcroco
arguments apply only if
the feature is enabled.
In this case, --with-croco
is
added to the configure script argument list and
libcroco
is added to
DEPENDS
.
On the other hand, if the feature is disabled say through
a .bbappend
file in another layer, then
the second argument --without-croco
is
added to the configure script rather than
--with-croco
.
The list of packages to be created from the recipe. The default value is the following:
${PN}-dbg ${PN}-staticdev ${PN}-dev ${PN}-doc ${PN}-locale ${PACKAGE_BEFORE_PN} ${PN}
A promise that your recipe satisfies runtime dependencies
for optional modules that are found in other recipes.
PACKAGES_DYNAMIC
does not actually satisfy the dependencies, it only states that
they should be satisfied.
For example, if a hard, runtime dependency
(RDEPENDS
) of another package is satisfied
at build time through the PACKAGES_DYNAMIC
variable, but a package with the module name is never actually
produced, then the other package will be broken.
Thus, if you attempt to include that package in an image,
you will get a dependency failure from the packaging system
during do_rootfs
.
Typically, if there is a chance that such a situation can
occur and the package that is not created is valid
without the dependency being satisfied, then you should use
RRECOMMENDS
(a soft runtime dependency)
instead of RDEPENDS
.
For an example of how to use the PACKAGES_DYNAMIC
variable when you are splitting packages, see the
"Handling Optional Module Packaging" section
in the Yocto Project Development Manual.
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.
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.
Specifies the recipe or package name and includes all version and revision
numbers (i.e. eglibc-2.13-r20+svnr15508/
and
bash-4.2-r1/
).
This variable is comprised of the following:
${PN}-${EXTENDPE}${PV}-${PR}
This variable can have two separate functions depending on the context: a recipe name or a resulting package name.
PN
refers to a recipe name in the context of a file used
by the OpenEmbedded build system as input to create a package.
The name is normally extracted from the recipe file name.
For example, if the recipe is named
expat_2.0.1.bb
, then the default value of PN
will be "expat".
The variable refers to a package name in the context of a file created or produced by the OpenEmbedded build system.
If applicable, the PN
variable also contains any special
suffix or prefix.
For example, using bash
to build packages for the native
machine, PN
is bash-native
.
Using bash
to build packages for the target and for Multilib,
PN
would be bash
and
lib64-bash
, respectively.
The revision of the recipe. The default value for this variable is "r0".
Causes the PR
variable of
.bbappend
files to dynamically increment.
This increment minimizes the impact of layer ordering.
In order to ensure multiple .bbappend
files can co-exist,
PRINC
should be self referencing.
This variable defaults to 0.
Following is an example that increments PR
by two:
PRINC := "${@int(PRINC) + 2}"
It is adviseable not to use strings such as ".= '.1'" with the variable because
this usage is very sensitive to layer ordering.
Explicit assignments should be avoided as they cannot adequately represent multiple
.bbappend
files.
The version of the recipe.
The version is normally extracted from the recipe filename.
For example, if the recipe is named
expat_2.0.1.bb
, then the default value of PV
will be "2.0.1".
PV
is generally not overridden within
a recipe unless it is building an unstable (i.e. development) version from a source code repository
(e.g. Git or Subversion).
the epoch of the recipe. The default value is "0". The field is used to make upgrades possible when the versioning scheme changes in some backwards incompatible way.
If multiple recipes provide an item, this variable
determines which recipe should be given preference.
The variable must always be suffixed with the name of the
provided item, and should be set to the
PN
of the recipe
to which you want to give precedence.
Here is an example:
PREFERRED_PROVIDER_virtual/xserver = "xserver-xf86"
If there are multiple versions of recipes available, this
variable determines which recipe should be given preference.
The variable must always be suffixed with the PN
for which to select, and should be set to the
PV
to which you want to give precedence.
You can use the "%
" character as a wildcard
to match any number of characters, which can be useful when
specifying versions that contain long revision number that could
potentially change.
Here are two examples:
PREFERRED_VERSION_python = "2.6.6" PREFERRED_VERSION_linux-yocto = "3.0+git%"
The list of packages that conflict with a package. Note that the package will not be installed if the conflicting packages are not first removed.
Like all package-controlling variables, you must always use them in conjunction with a package name override. Here is an example:
RCONFLICTS_${PN} = "another-conflicting-package-name"
Lists a package's run-time dependencies (i.e. other packages) that must be installed for the package to be built. In other words, in order for the package to be built and run correctly, it depends on the listed packages. If a package in this list cannot be found, it is probable that a dependency error would occur before the build.
The names of the variables you list with
RDEPENDS
must be the names of other
packages as listed in the
PACKAGES
variable.
You should not list recipe names (PN
).
Because the RDEPENDS
variable applies
to packages being built, you should
always attach a package name to the variable to specify the
particular run-time package that has the dependency.
For example, suppose you are building a development package
that depends on the perl
package.
In this case, you would use the following
RDEPENDS
statement:
RDEPENDS_${PN}-dev += "perl"
In the example, the package name
(${PN}-dev
) must appear as it would
in the
PACKAGES
namespace before any renaming of the output package by
classes like debian.bbclass
.
In many cases you do not need to explicitly add dependencies
to RDEPENDS
since some automatic
handling occurs:
shlibdeps
: If
a run-time package contains a shared library
(.so
), the build
processes the library in order to determine other
libraries to which it is dynamically linked.
The build process adds these libraries to
RDEPENDS
when creating the run-time
package.
pcdeps
: If
the package ships a pkg-config
information file, the build process uses this file
to add items to the RDEPENDS
variable to create the run-time packages.
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
RDEPENDS
variable.
The OpenEmbedded build process automatically installs the list of packages as part of the built package. However, you can remove them later if you want. If, during the build, a package from the list cannot be found, the build process continues without an error.
Because the RRECOMMENDS
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:
RRECOMMENDS_${PN}-dev += "<wireless_package_name>"
In the example, the package name (${PN}-dev
) must
appear as it would in the
PACKAGES
namespace before any
renaming of the output package by classes like debian.bbclass
.
The list of packages that are replaced with this package.
The location in the Build Directory
where unpacked package source code resides.
This location is within the working directory
(WORKDIR
), which
is not static.
The unpacked source location depends on the package name
(PN
) and
package version (PV
) as
follows:
${WORKDIR}/${PN}-${PV}
As an example, assume a
Source Directory top-level
folder named poky
and a default Build Directory
at poky/build
.
In this case, the working directory the build system uses to build
the db
package is the following:
~/poky/build/tmp/work/qemux86-poky-linux/db-5.1.19-r3/db-5.1.19
Equivalent to
IMAGE_FEATURES
.
However, this variable applies to the SDK generated from an image using
bitbake -c populate_sdk imagename
).
The section in which packages should be categorized. Package management utilities can make use of this variable.
The variable takes the value of
FULL_OPTIMIZATION
unless DEBUG_BUILD
= "1".
In this case the value of
DEBUG_OPTIMIZATION
is used.
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.
Specifies the endian byte order of the target system. The value should be either "le" for little-endian or "be" for big-endian.
Specifies the number of bits for the target system CPU. The value should be either "32" or "64".
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.
The list of source files - local or remote.
This variable tells the OpenEmbedded build system which bits to pull
in for the build and how to pull them in.
For example, if the recipe only needs to fetch a tarball from the
internet, the recipe uses a single SRC_URI
entry.
On the other hand, if the recipe needs to fetch a tarball, apply
two patches, and include a custom file, the recipe would include four
instances of the variable.
The following list explains the available URI protocols:
file://
- Fetches files, which is usually
a file shipped with the metadata, from the local machine.
The path is relative to the
FILESPATH
variable.
Thus, the build system searches, in order, from the following directories,
which are assumed to be a subdirectories of the directory in which the
recipe file resides:
${PN}
- The recipe name
with any special suffix or prefix, if applicable.
For example, using bash
to build for the native
machine, PN
is bash-native
.
Using bash
to build for the target and for Multilib,
PN
would be bash
and
lib64-bash
, respectively.
${PF}
-
${PN}-${EXTENDPE}${PV}-${PR}
.
The recipe name including all version and revision numbers
(i.e. eglibc-2.13-r20+svnr15508/
and
bash-4.2-r1/
).
${P}
-
${PN}-${PV}
.
The recipe name and version (i.e. bash-4.2
).
${BPN}
- The
base recipe name without any special suffix or version numbers.
${BP}
-
${BPN}-${PV}
.
The base recipe name and version but without any special
package name suffix.
Files - Files beneath the directory in which the recipe resides.
Directory - The directory itself in which the recipe resides.
bzr://
- Fetches files from a
Bazaar revision control repository.
git://
- Fetches files from a
Git revision control repository.
osc://
- Fetches files from
an OSC (OpenSuse Build service) revision control repository.
repo://
- Fetches files from
a repo (Git) repository.
svk://
- Fetches files from
an SVK revision control repository.
http://
- Fetches files from
the Internet using http
.
https://
- Fetches files
from the Internet using https
.
ftp://
- Fetches files
from the Internet using ftp
.
cvs://
- Fetches files from
a CVS revision control repository.
hg://
- Fetches files from
a Mercurial (hg
) revision control repository.
p4://
- Fetches files from
a Perforce (p4
) revision control repository.
ssh://
- Fetches files from
a secure shell.
svn://
- Fetches files from
a Subversion (svn
) revision control repository.
Standard and recipe-specific options for SRC_URI
exist.
Here are standard options:
apply
- Whether to apply
the patch or not.
The default action is to apply the patch.
striplevel
- Which
striplevel to use when applying the patch.
The default level is 1.
Here are options specific to recipes building code from a revision control system:
mindate
- Only applies
the patch if SRCDATE
is equal to or greater than mindate
.
maxdate
- Only applies
the patch if SRCDATE
is not later than mindate
.
minrev
- Only applies
the patch if SRCREV
is equal to or greater than minrev
.
maxrev
- Only applies
the patch if SRCREV
is not later than maxrev
.
rev
- Only applies the
patch if SRCREV
is equal to rev
.
notrev
- Only applies
the patch if SRCREV
is not equal to rev
.
Here are some additional options worth mentioning:
unpack
- Controls
whether or not to unpack the file if it is an archive.
The default action is to upack the file.
subdir
- Places the file
(or extracts its contents) into the specified
subdirectory of WORKDIR
.
This option is useful for unusual tarballs or other archives that
don't have their files already in a subdirectory within the archive.
name
- Specifies a
name to be used for association with SRC_URI
checksums
when you have more than one file specified in SRC_URI
.
downloadfilename
- Specifies
the filename used when storing the downloaded file.
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.
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).
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 SRCREV
that is a
full revision identifier and not just a tag.
The directory for the shared state.
Configures the OpenEmbedded build system to search other
mirror locations for prebuilt cache data objects before
building out the data.
This variable works like fetcher
MIRRORS
/PREMIRRORS
and points to the cache locations to check for the shared
objects.
You can specify a filesystem directory or a remote URL such as HTTP or FTP. The locations you specify need to contain the shared state cache (sstate-cache) results from previous builds. The sstate-cache you point to can also be from builds on other machines.
If a mirror uses the same structure as
SSTATE_DIR
,
you need to add
"PATH" at the end as shown in the examples below.
The build system substitues the correct path within the
directory structure.
SSTATE_MIRRORS ?= "\ file://.* http://someserver.tld/share/sstate/PATH \n \ file://.* file:///some/local/dir/sstate/PATH"
The directory with kernel headers that are required to build out-of-tree modules.
Specifies the base path used to create recipe stamp files.
The path to an actual stamp file is constructed by evaluating this
string and then appending additional information.
Currently, the default assignment for STAMP
as set in the meta/conf/bitbake.conf
file
is:
STAMP = "${TMPDIR}/stamps/${MULTIMACH_TARGET_SYS}/${PN}-${EXTENDPE}${PV}-${PR}"
See TMPDIR
,
MULTIMACH_TARGET_SYS
,
PN
,
EXTENDPE
,
PV
, and
PR
for related variable
information.
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.
This variable points to a directory were Bitbake places temporary files when building a particular package. It is typically set as follows:
T = ${WORKDIR}/temp
The WORKDIR
is the directory into which Bitbake unpacks and builds the package.
The default bitbake.conf
file sets this variable.
The T
variable is not to be confused with
the TMPDIR
variable,
which points to the root of the directory tree where Bitbake
places the output of an entire build.
The architecture of the device being built.
While a number of values are possible, the OpenEmbedded build system primarily supports
arm
and i586
.
Flags passed to the C compiler for the target system.
This variable evaluates to the same as
CFLAGS
.
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.
Specifies the target's operating system.
The variable can be set to "linux" for eglibc
-based systems and
to "linux-uclibc" for uclibc
.
For ARM/EABI targets, there are also "linux-gnueabi" and
"linux-uclibc-gnueabi" values possible.
Specifies which variant of the GNU standard C library (libc
)
to use during the build process.
This variable replaces POKYLIBC
, which is no longer
supported.
You can select eglibc
or uclibc
.
glibc
implementation of libc
.
The toolchain selector.
This variable replaces POKYMODE
, which is no longer
supported.
The TCMODE
variable selects the external toolchain
built using the OpenEmbedded build system or a few supported combinations of
the upstream GCC or CodeSourcery Labs toolchain.
The variable identifies the tcmode-*
files used in
the meta/conf/distro/include
directory, which is found in the
Source Directory.
By default, TCMODE
is set to "default", which
chooses the tcmode-default.inc
file.
The variable is similar to
TCLIBC
, which controls
the variant of the GNU standard C library (libc
)
used during the build process: eglibc
or uclibc
.
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.
If you want to establish this directory in a location other than the
default, you can uncomment the following statement in the
conf/local.conf
file in the
Source Directory:
#TMPDIR = "${TOPDIR}/tmp"
This variable is the Build Directory. BitBake automatically sets this variable. The OpenEmbedded build system uses the Build Directory when building images.
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.
The actual WORKDIR
directory depends on several things:
For packages that are not dependent on a particular machine,
WORKDIR
is defined as follows:
${TMPDIR}/work/${PACKAGE_ARCH}-poky-${TARGET_OS}/${PN}-${PV}-${PR}
As an example, assume a
Source Directory top-level
folder name poky
and a default
Build Directory
at poky/build
.
In this case, the working directory the build system uses to build
the v86d
package is the following:
~/poky/build/tmp/work/qemux86-poky-linux/v86d-01.9-r0
For packages that are dependent on a particular machine, WORKDIR
is defined slightly different:
${TMPDIR}/work/${MACHINE}-poky-${TARGET_OS}/${PN}-${PV}-${PR}
As an example, again assume a Source Directory top-level folder
named poky
and a default Build Directory
at poky/build
.
In this case, the working directory the build system uses to build
the acl
recipe, which is being built for a
MIPS-based device, is the following:
~/poky/build/tmp/work/mips-poky-linux/acl-2.2.51-r2