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_${PN} = "1"
The email address used to contact the original author or authors in order to send patches and forward bugs.
When SRCREV
is set to the value of this variable, it specifies to use the latest
source revision in the repository.
Here is an example:
SRCREV = "${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.
Defines how BitBake handles situations where an append
file (.bbappend
) has no
corresponding recipe file (.bb
).
This condition often occurs when layers get out of sync
(e.g. oe-core
bumps a
recipe version and the old recipe no longer exists and the
other layer has not been updated to the new version
of the recipe yet).
The default fatal behavior is safest because it is the sane reaction given something is out of sync. It is important to realize when your changes are no longer being applied.
You can change the default behavior by setting this
variable to "1" in the local.conf
file in the
Build Directory
as follows:
BB_DANGLINGAPPENDS_WARNONLY = "1"
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 initial 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.
Use the BBMASK
variable from within the
conf/local.conf
file found
in the
Build Directory.
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. The expression is compared against the full paths to the files. For complete syntax information, see Python's documentation at http://docs.python.org/release/2.3/lib/re-syntax.html.
The following example 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/"
If you want to mask out multiple directories or recipes, use the vertical bar to separate the regular expression fragments. This next example masks out multiple directories and individual recipes:
BBMASK = "meta-ti/recipes-misc/|meta-ti/recipes-ti/packagegroup/" BBMASK .= "|.*meta-oe/recipes-support/" BBMASK .= "|.*openldap" BBMASK .= "|.*opencv" BBMASK .= "|.*lzma"
Notice how the vertical bar is used to append the fragments.
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 \ " BBLAYERS_NON_REMOVABLE ?= " \ /home/scottrif/poky/meta \ /home/scottrif/poky/meta-yocto \ "
This example enables four layers, one of which is a custom, user-defined layer
named meta-mykernel
.
Lists core layers that cannot be removed from the
bblayers.conf
file.
In order for BitBake to build your image, your
bblayers.conf
file must include the
meta
and meta-yocto
core layers.
Here is an example that shows these two layers listed in
the BBLAYERS_NON_REMOVABLE
statement:
BBLAYERS = " \ /home/scottrif/poky/meta \ /home/scottrif/poky/meta-yocto \ /home/scottrif/poky/meta-yocto-bsp \ /home/scottrif/poky/meta-mykernel \ " BBLAYERS_NON_REMOVABLE ?= " \ /home/scottrif/poky/meta \ /home/scottrif/poky/meta-yocto \ "
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.
Points to the location of the
Build Directory.
You can define this directory indirectly through the
oe-init-build-env
script by passing in a Build Directory path when you run the
script.
If you run the script and do not provide a Build Directory
path, the BUILDDIR
defaults to
build
in the current directory.
Flags passed to the 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 that resolves to one or more hosts
(when the recipe is native) or one or more targets (when
the recipe is non-native) with which a recipe is compatible.
The regular expression is matched against
HOST_SYS
.
You can use the variable to stop recipes from being built
for classes of systems with which the recipes are not
compatible.
Stopping these builds is particularly useful with kernels.
The variable also helps to increase parsing speed
since the build system skips parsing recipes not
compatible with the current system.
A regular expression that resolves to one or more
target machines with which a recipe is compatible.
The regular expression is matched against
MACHINEOVERRIDES
.
You can use the variable to stop recipes from being built
for machines with which the recipes are not compatible.
Stopping these builds is particularly useful with kernels.
The variable also helps to increase parsing speed
since the build system skips parsing recipes not
compatible with the current machine.
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.
You should only set this variable 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 a weak bias for recipe selection priority.
The most common usage of this is variable is to set
it to "-1" within a recipe for a development version of a
piece of software.
Using the variable in this way causes the stable version
of the recipe to build by default in the absence of
PREFERRED_VERSION
being used to build the development version.
DEFAULT_PREFERENCE
is weak and is overridden by
BBFILE_PRIORITY
if the that variable is different between two layers
that contain different versions of the same recipe.
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 you can remove them.
The features enabled for the distribution. For a list of supported features that ship with the Yocto Project, 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 be 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.
This variable lists overrides specific to the current
distribution.
By default, the variable list includes the value of the
DISTRO
variable.
You can extend the variable to apply any variable overrides
you want as part of the distribution and are not
already in OVERRIDES
through
some other means.
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 this specific question in the "FAQ" chapter.
Variable that controls which locales for
eglibc
are 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.
The list of additional features to include in an image.
Typically, you configure this variable in your
local.conf
file, which is found in the
Build Directory.
Although you can use this variable from within a recipe,
best practices dictate that you do not.
IMAGE_FEATURES
variable.
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. "debug-tweaks" - Makes an image suitable for development. For example, ssh root access has a blank password. You should remove this feature before you produce a production image. "dev-pkgs" - Adds -dev packages for all installed packages. This is useful if you want to develop against the libraries in the image. "read-only-rootfs" - Creates an image whose root filesystem is read-only. See the "Creating a Read-Only Root Filesystem" section in the Yocto Project Development Manual for more information "tools-debug" - Adds debugging tools such as gdb and strace. "tools-profile" - Adds profiling tools such as oprofile, exmap, lttng and valgrind (x86 only). "tools-sdk" - Adds development tools such as gcc, make, pkgconfig and so forth. "tools-testapps" - Adds useful testing tools such as ts_print, aplay, arecord and so forth.
For a complete list of image features that ships with the Yocto Project, see the "Images" section.
For an example that shows how to customize your image by
using this variable, see the
"Customizing Images Using Custom IMAGE_FEATURES
and EXTRA_IMAGE_FEATURES
"
section in the Yocto Project Development Manual.
A list of recipes to build that do not provide packages for installing into 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.
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 ${bindir}
rather
than /usr/bin
.
You can find a list of these variables at the top of the
/meta/conf/bitbake.conf
file in the
Source Directory.
If some of the files you provide with the FILES
variable
are editable and you know they should not be
overwritten during the package update process by the Package Management
System (PMS), you can identify these files so that the PMS will not
overwrite them.
See the CONFFILES
variable for information on how to identify these files to the PMS.
Extends the search path the OpenEmbedded build system uses
when looking for files and patches as it processes recipes
and append files.
The directories BitBake uses when it processes recipes
are defined by the
FILESPATH
variable, and can be extended using
FILESEXTRAPATHS
.
Best practices dictate that you accomplish this by using the
variable from within a .bbappend
file
and that you prepend paths as follows:
FILESEXTRAPATHS_prepend := "${THISDIR}/${PN}:"
In the above example, the build system looks for files in a directory that has the same name as the corresponding append file.
When extending FILESEXTRAPATHS
,
be sure to use the immediate expansion
(:=
) operator.
Immediate expansion makes sure that BitBake evaluates
THISDIR
at the time the directive
is encountered rather than at some later time when
expansion might result in a directory that does not
contain the files you need.
Also, include the trailing separating colon character if you are prepending. The trailing colon character is necessary because you are directing BitBake to extend the path by prepending directories to the search path.
Here is another common use:
FILESEXTRAPATHS_prepend := "${THISDIR}/files:"
In this example, the build system extends the
FILESPATH
variable to include a
directory named files
that is in the
same directory as the corresponding append file.
Here is a final example that specifically adds three paths:
FILESEXTRAPATHS_prepend := "path_1:path_2:path_3:"
By prepending paths in .bbappend
files, you allow multiple append files that reside in
different layers but are used for the same recipe to
correctly extend the path.
:=
) operator and include
the trailing separating colon character.
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}/${BP}", \ "${FILE_DIRNAME}/${BPN}", "${FILE_DIRNAME}/files"], d)}"
FILESPATH
variable.
Be aware that the default FILESPATH
directories do not map to directories in custom layers
where append files (.bbappend
)
are used.
If you want the build system to find patches or files
that reside with your append files, you need to extend
the FILESPATH
variable by using
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".
Website where more information about the software the recipe is building can be found.
Specifies the system, including the architecture and the operating system, for with the build is occurring in the context of the current recipe. The OpenEmbedded build system automatically sets this variable. You do not need to set the variable yourself.
Here are two examples:
Given a native recipe on a 32-bit x86 machine running Linux, the value is "i686-linux".
Given a recipe being built for a little-endian MIPS target running Linux, the value might be "mipsel-linux".
The primary list of features to include in an image.
Typically, you configure this variable in an image recipe.
Although you can use this variable from your
local.conf
file, which is found in the
Build Directory,
best practices dictate that you do not.
EXTRA_IMAGE_FEATURES
variable.
For a list of image features that ships with the Yocto Project, see the "Images" section.
For example that shows how to customize your image by
using this variable, see the
"Customizing Images Using Custom IMAGE_FEATURES
and EXTRA_IMAGE_FEATURES
"
section in the Yocto Project Development Manual.
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.
Specifies the list of locales to install into the image
during the root filesystem construction process.
The OpenEmbedded build system automatically splits locale
files, which are used for localization, into separate
packages.
Setting the IMAGE_LINGUAS
variable
ensures that any locale packages that correspond to packages
already selected for installation into the image are also
installed.
Here is an example:
IMAGE_LINGUAS = "pt-br de-de"
In this example, the build system ensures any Brazilian
Portuguese and German locale files that correspond to
packages in the image are installed (i.e.
*-locale-pt-br
and *-locale-de-de
as well as
*-locale-pt
and *-locale-de
, since some software
packages only provide locale files by language and not by
country-specific language).
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
See the IMAGE_OVERHEAD_FACTOR
and IMAGE_ROOTFS_EXTRA_SPACE
variables for related information.
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
that are used in many places and 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.
If set to "1", 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
.
Here is an example:
INITSCRIPT_PARAMS = "start 99 5 2 . stop 20 0 1 6 ."
In this example, the script has a runlevel of 99, starts the script in initlevels 2 and 5, and stops the script in levels 0, 1 and 6.
The variable is mandatory and is used in recipes when using
update-rc.d.bbclass
.
Specifies the QA checks to skip for a specific package
within a recipe.
For example, to skip the check for symbolic link
.so
files in the main package of a
recipe, add the following to the recipe.
The package name override must be used, which in this
example is ${PN}
:
INSANE_SKIP_${PN} += "dev-so"
See the "Generated Output Quality Assurance Checks - insane.bbclass
"
section for a list of the valid QA checks you can
specify using this variable.
Defines the kernel architecture used when assembling the configuration. Architectures supported for this release are:
powerpc arm i386 mips powerpc x86_64
You define the KARCH
variable in the
BSP Descriptions.
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.
Defines the Linux kernel source repository's default
branch used to build the Linux kernel.
The KBRANCH_DEFAULT
value is
the default value for
KBRANCH
.
Unless you specify otherwise,
KBRANCH_DEFAULT
initializes to
"master".
Specifies additional make
command-line arguments the OpenEmbedded build system
passes on when compiling the kernel.
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 location of the kernel sources.
This variable is set to the value of the
STAGING_KERNEL_DIR
within the module.bbclass
class.
For information on how this variable is used, see the
"Incorporating Out-of-Tree Modules"
section.
The KERNEL_SRC
variable is identical to the KERNEL_PATH
variable.
The location of the kernel sources.
This variable is set to the value of the
STAGING_KERNEL_DIR
within the module.bbclass
class.
For information on how this variable is used, see the
"Incorporating Out-of-Tree Modules"
section.
The KERNEL_PATH
variable is identical to the KERNEL_SRC
variable.
Provides a short description of a configuration fragment.
You use this variable in the .scc
file that describes a configuration fragment file.
Here is the variable used in a file named
smp.scc
to describe SMP being
enabled:
define KFEATURE_DESCRIPTION "Enable SMP"
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's 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 Board Support Package (BSP) as
cedartrail
.
If you look in the Cedar Trail BSP layer in the
meta-intel
Source Repositories
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 proprietary
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.
Defines the kernel type to be used in assembling the configuration. The linux-yocto recipes define "standard", "tiny", and "preempt-rt" kernel types. See the "Kernel Types" section in the Yocto Project Linux Kernel Development Manual for more information on kernel types.
You define the KTYPE
variable in the
BSP Descriptions.
The value you use must match the value used for the
LINUX_KERNEL_TYPE
value used by the kernel recipe.
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 is not available outside of layer.conf
and references are expanded immediately when parsing of the file completes.
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"
Defines the kernel type to be used in assembling the configuration. The linux-yocto recipes define "standard", "tiny", and "preempt-rt" kernel types. See the "Kernel Types" section in the Yocto Project Linux Kernel Development Manual for more information on kernel types.
If you do not specify a
LINUX_KERNEL_TYPE
, it defaults to
"standard".
Together with
KMACHINE
,
the LINUX_KERNEL_TYPE
variable
defines the search
arguments used by the kernel tools to find the appropriate
description within the kernel
Metadata
with which to build out the sources and configuration.
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.
For example, the linux-yocto-3.4.bb
kernel recipe found in
meta/recipes-kernel/linux
defines the variables as follows:
LINUX_VERSION ?= "3.4.24"
The LINUX_VERSION
variable is used to
define PV
for the recipe:
PV = "${LINUX_VERSION}+git${SRCPV}"
A string extension compiled into the version string of the Linux kernel built with the OpenEmbedded build system. You define this variable in the kernel recipe. For example, the linux-yocto kernel recipes all define the variable as follows:
LINUX_VERSION_EXTENSION ?= "-yocto-${LINUX_KERNEL_TYPE}"
Defining this variable essentially sets the
Linux kernel configuration item
CONFIG_LOCALVERSION
, which is visible
through the uname
command.
Here is an example that shows the extension assuming it
was set as previously shown:
$ uname -r 3.7.0-rc8-custom
Specifies the directory to which the OpenEmbedded build
system writes overall log files.
The default directory is ${TMPDIR}/log
.
For the directory containing logs specific to each task,
see the T
variable.
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.
Lists overrides specific to the current machine.
By default, this list includes the value
of MACHINE
.
You can extend the list to apply variable overrides for
classes of machines.
For example, all QEMU emulated machines (e.g. qemuarm,
qemux86, and so forth) include a common file named
meta/conf/machine/include/qemu.inc
that prepends MACHINEOVERRIDES
with
the following variable override:
MACHINEOVERRIDES =. "qemuall:"
Applying an override like qemuall
affects all QEMU emulated machines elsewhere.
Here is an example from the
connman-conf
recipe:
SRC_URI_append_qemuall = "file://wired.config \ file://wired-setup \ "
The email address of the distribution maintainer.
Specifies additional paths from which the OpenEmbedded
build system gets source code.
When the build system searches for source code, it first
tries the local download directory.
If that location fails, the build system tries locations
defined by
PREMIRRORS
,
the upstream source, and then locations specified by
MIRRORS
in that order.
Assuming your distribution
(DISTRO
)
is "poky", the default value for
MIRRORS
is defined in the
conf/distro/poky.conf
file in the
meta-yocto
Git repository.
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
.
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.
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.
A string identifying the host distribution.
Strings consist of the host distributor ID
followed by the release, as reported by the
lsb_release
tool
or as read from /etc/lsb-release
.
For example, when running a build on Ubuntu 12.10, the value
is "Ubuntu-12.10".
If this information is unable to be determined, the value
resolves to "Unknown".
This variable is used by default to isolate native shared
state packages for different distributions (e.g. to avoid
problems with glibc
version
incompatibilities).
Additionally, the variable is checked against
SANITY_TESTED_DISTROS
if that variable is set.
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".
Specifies additional paths from which the OpenEmbedded
build system gets source code.
When the build system searches for source code, it first
tries the local download directory.
If that location fails, the build system tries locations
defined by PREMIRRORS
, the upstream
source, and then locations specified by
MIRRORS
in that order.
Assuming your distribution
(DISTRO
)
is "poky", the default value for
PREMIRRORS
is defined in the
conf/distro/poky.conf
file in the
meta-yocto
Git repository.
Typically, you could add a specific server for the
build system to attempt before any others by adding
something like the following to the
local.conf
configuration file in the
Build Directory:
PREMIRRORS_prepend = "\ git://.*/.* http://www.yoctoproject.org/sources/ \n \ ftp://.*/.* http://www.yoctoproject.org/sources/ \n \ http://.*/.* http://www.yoctoproject.org/sources/ \n \ https://.*/.* http://www.yoctoproject.org/sources/ \n"
These changes cause the build system to intercept
Git, FTP, HTTP, and HTTPS requests and direct them to
the http://
sources mirror.
You can use file://
URLs to point
to local directories or network shares as well.
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 advisable not to use strings such as ".= '.1'" with the variable because
this usage is very sensitive to layer ordering.
You should avoid explicit assignments as they cannot
adequately represent multiple
.bbappend
files.
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
).
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.
You should always suffix the variable with the name of the
provided item, and you should set it 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.
You must always suffix the variable with the
PN
you want to select, and you should set to the
PV
accordingly for 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 another 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 in order for the built package to run correctly. If a package in this list cannot be found during the build, you will get a build error.
The names of the packages you list within
RDEPENDS
must be the names of other
packages - they cannot be recipe names.
Although package names and recipe names usually match,
the important point here is that you are
providing package names within the
RDEPENDS
variable.
For an example of the default list of packages created from
a recipe, see the
PACKAGES
variable.
Because the RDEPENDS
variable applies
to packages being built, you should always use the variable
in a form with an attached package name.
For example, suppose you are building a development package
that depends on the perl
package.
In this case, you would use the following
RDEPENDS
statement:
RDEPENDS_${PN}-dev += "perl"
In the example, the development package depends on
the perl
package.
Thus, the RDEPENDS
variable has the
${PN}-dev
package name as part of the
variable.
The package name you attach to the
RDEPENDS
variable must appear
as it would in the PACKAGES
namespace before any renaming of the output package by
classes like debian.bbclass
.
In many cases you do not need to explicitly add
run-time dependencies using
RDEPENDS
since some automatic
handling occurs:
shlibdeps
: If
a run-time package contains a shared library
(.so
), the build
processes the library in order to determine other
libraries to which it is dynamically linked.
The build process adds these libraries to
RDEPENDS
when creating the run-time
package.
pcdeps
: If
the package ships a pkg-config
information file, the build process uses this file
to add items to the RDEPENDS
variable to create the run-time packages.
With rm_work
enabled, this
variable specifies a list of recipes whose work directories
should not be removed.
See the "Removing Work Files During the Build - rm_work.bbclass
"
section for more details.
A list of package name aliases that a package also provides.
These aliases are useful for satisfying runtime dependencies
of other packages both during the build and on the target
(as specified by
RDEPENDS
).
RPROVIDES
list.
As with all package-controlling variables, you must always use the variable in conjunction with a package name override. Here is an example:
RPROVIDES_${PN} = "widget-abi-2"
A list of packages that extends the usability of a package being
built.
The package being built does not depend on this list of packages in
order to successfully build, but needs them for the extended usability.
To specify runtime dependencies for packages, see the
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
.
A list of packages replaced by a package.
The package manager uses this variable to determine which
package should be installed to replace other package(s)
during an upgrade.
In order to also have the other package(s) removed at the
same time, you must add the name of the other
package to the
RCONFLICTS
variable.
As with all package-controlling variables, you must use this variable in conjunction with a package name override. Here is an example:
RREPLACES_${PN} = "other-package-being-replaced"
A list of additional packages that you can suggest for installation by the package manager at the time a package is installed. Not all package managers support this functionality.
As with all package-controlling variables, you must always use this variable in conjunction with a package name override. Here is an example:
RSUGGESTS_${PN} = "useful-package another-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
A list of the host distribution identifiers that the
build system has been tested against.
Identifiers consist of the host distributor ID
followed by the release,
as reported by the lsb_release
tool
or as read from /etc/lsb-release
.
Separate the list items with explicit newline
characters (\n
).
If SANITY_TESTED_DISTROS
is not empty
and the current value of
NATIVELSBSTRING
does not appear in the list, then the build system reports
a warning that indicates the current host distribution has
not been tested as a build host.
Equivalent to
IMAGE_FEATURES
.
However, this variable applies to the SDK generated from an
image using the following command:
$ 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.
A list of recipes that are completely stable and will never change. The ABI for the recipes in the list are presented by output from the tasks run to build the recipe. Use of this variable is one way to remove dependencies from one recipe on another that affect task signatures and thus force rebuilds when the recipe changes.
A list of recipe dependencies that should not be used to determine signatures of tasks from one recipe when they depend on tasks from another recipe. For example:
SIGGEN_EXCLUDE_SAFE_RECIPE_DEPS += "intone->mplayer2"
In this example, intone
depends on
mplayer2
.
Use of this variable is one mechanism to remove dependencies that affect task signatures and thus force rebuilds when a recipe changes.
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".
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.
conf/machine/include/soc-family.inc
for this variable to appear in
MACHINEOVERRIDES
.
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 or append file only needs to
fetch a tarball from the Internet, the recipe or
append file uses a single SRC_URI
entry.
On the other hand, if the recipe or append file needs to
fetch a tarball, apply two patches, and include a custom
file, the recipe or append file would include four
instances of the variable.
The following list explains the available URI protocols:
file://
-
Fetches files, which are usually files 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 (.bb
) or
append file (.bbappend
)
resides:
${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 within a directory, which is named
files
and is also
alongside the recipe or append file.
SRC_URI
statement from your append file, you need to be
sure to extend the
FILESPATH
variable by also using the
FILESEXTRAPATHS
variable from within your append file.
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
-
Apply the patch only if
SRCDATE
is equal to or greater than mindate
.
maxdate
-
Apply the patch only if SRCDATE
is not later than mindate
.
minrev
-
Apply the patch only if SRCREV
is equal to or greater than minrev
.
maxrev
-
Apply the patch only if SRCREV
is not later than maxrev
.
rev
-
Apply the patch only if SRCREV
is equal to rev
.
notrev
-
Apply the patch only 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 unpack 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
do not 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).
Returns the version string of the current package.
This string is used to help define the value of
PV
.
The SRCPV
variable is defined in the
meta/conf/bitbake.conf
configuration
file in the
Source Directory
as follows:
SRCPV = "${@bb.fetch2.get_srcrev(d)}"
Recipes that need to define PV
do so
with the help of the SRCPV
.
For example, the ofono
recipe
(ofono_git.bb
) located in
meta/recipes-connectivity
in the
Source Directory defines PV
as
follows:
PV = "1.5.0+git${SRCPV}"
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 cache.
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
and 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 substitutes 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 = "${STAMPS_DIR}/${MULTIMACH_TARGET_SYS}/${PN}/${EXTENDPE}${PV}-${PR}"
See STAMPS_DIR
,
MULTIMACH_TARGET_SYS
,
PN
,
EXTENDPE
,
PV
, and
PR
for related variable
information.
Specifies the base directory in which the OpenEmbedded
build system places stamps.
The default directory is
${TMPDIR}/stamps
.
The short (72 characters or less) summary of the binary package for packaging
systems such as opkg
, rpm
or
dpkg
.
By default, SUMMARY
is used to define
the DESCRIPTION
variable if DESCRIPTION
is not set
in the recipe.
A list of functions to execute after files are staged into the sysroot. These functions are usually used to apply additional processing on the staged files, or to stage additional files.
This variable points to a directory were BitBake places temporary files, which consist mostly of task logs and scripts, when building a particular recipe. The variable is typically set as follows:
T = "${WORKDIR}/temp"
The WORKDIR
is the directory into which BitBake unpacks and builds the
recipe.
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. The OpenEmbedded build system supports the following architectures:
arm mips ppc x86 x86-64
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
.
The directory in which the file BitBake is currently parsing is located. Do not manually set this variable.
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