Bitbake is the primary command in the system. It facilitates executing tasks in a single .bb file, or executing a given task on a set of multiple .bb files, accounting for interdependencies amongst them.

Following is the usage and syntax for BitBake: $ bitbake -h Usage: bitbake [options] [recipename/target ...] Executes the specified task (default is 'build') for a given set of target recipes (.bb files). It is assumed there is a conf/bblayers.conf available in cwd or in BBPATH which will provide the layer, BBFILES and other configuration information. Options: --version show program's version number and exit -h, --help show this help message and exit -b BUILDFILE, --buildfile=BUILDFILE Execute tasks from a specific .bb recipe directly. WARNING: Does not handle any dependencies from other recipes. -k, --continue Continue as much as possible after an error. While the target that failed and anything depending on it cannot be built, as much as possible will be built before stopping. -a, --tryaltconfigs Continue with builds by trying to use alternative providers where possible. -f, --force Force the specified targets/task to run (invalidating any existing stamp file). -c CMD, --cmd=CMD Specify the task to execute. The exact options available depend on the metadata. Some examples might be 'compile' or 'populate_sysroot' or 'listtasks' may give a list of the tasks available. -C INVALIDATE_STAMP, --clear-stamp=INVALIDATE_STAMP Invalidate the stamp for the specified task such as 'compile' and then run the default task for the specified target(s). -r PREFILE, --read=PREFILE Read the specified file before bitbake.conf. -R POSTFILE, --postread=POSTFILE Read the specified file after bitbake.conf. -v, --verbose Output more log message data to the terminal. -D, --debug Increase the debug level. You can specify this more than once. -n, --dry-run Don't execute, just go through the motions. -S, --dump-signatures Don't execute, just dump out the signature construction information. -p, --parse-only Quit after parsing the BB recipes. -s, --show-versions Show current and preferred versions of all recipes. -e, --environment Show the global or per-package environment complete with information about where variables were set/changed. -g, --graphviz Save dependency tree information for the specified targets in the dot syntax. -I EXTRA_ASSUME_PROVIDED, --ignore-deps=EXTRA_ASSUME_PROVIDED Assume these dependencies don't exist and are already provided (equivalent to ASSUME_PROVIDED). Useful to make dependency graphs more appealing -l DEBUG_DOMAINS, --log-domains=DEBUG_DOMAINS Show debug logging for the specified logging domains -P, --profile Profile the command and save reports. -u UI, --ui=UI The user interface to use (e.g. knotty, hob, depexp). -t SERVERTYPE, --servertype=SERVERTYPE Choose which server to use, process or xmlrpc. --revisions-changed Set the exit code depending on whether upstream floating revisions have changed or not. --server-only Run bitbake without a UI, only starting a server (cooker) process. -B BIND, --bind=BIND The name/address for the bitbake server to bind to. --no-setscene Do not run any setscene tasks. sstate will be ignored and everything needed, built. --remote-server=REMOTE_SERVER Connect to the specified server. -m, --kill-server Terminate the remote server. --observe-only Connect to a server as an observing-only client. --status-only Check the status of the remote bitbake server.

This section presents some examples showing how to use BitBake.

Executing tasks for a single recipe file is relatively simple. You specify the file in question, and BitBake parses it and executes the specified task (or “build” by default). BitBake obeys inter-task dependencies when doing so. The following command runs the clean task on the foo_1.0.bb recipe file: $ bitbake -b foo.bb -c clean The following command runs the build task, which is the default task, on the foo_1.0.bb recipe file: $ bitbake -b foo_1.0.bb

There are a number of additional complexities introduced when one wants to manage multiple .bb files. Clearly there needs to be a way to tell BitBake what files are available, and of those, which we want to execute at this time. There also needs to be a way for each .bb to express its dependencies, both for build-time and runtime. There must be a way for the user to express their preferences when multiple recipes provide the same functionality, or when there are multiple versions of a .bb file. The next section, Metadata, outlines how to specify such things. The bitbake command, when not using "--buildfile", accepts a PROVIDER, not a filename or anything else. By default, a .bb generally PROVIDES its packagename, packagename-version, and packagename-version-revision. $ bitbake foo $ bitbake foo-1.0 $ bitbake foo-1.0-r0 $ bitbake -c clean foo $ bitbake virtual/whatever $ bitbake -c clean virtual/whatever

BitBake is able to generate dependency graphs using the dot syntax. These graphs can be converted to images using the dot application from Graphviz. Two files will be written into the current working directory: depends.dot containing dependency information at the package level and task-depends.dot containing a breakdown of the dependencies at the task level. To stop depending on common depends, one can use the "-I" depend option to omit these from the graph. This can lead to more readable graphs. This way, DEPENDS from inherited classes such as base.bbclass can be removed from the graph. $ bitbake -g foo $ bitbake -g -I virtual/whatever -I bloom foo

Certain variables affect BitBake operation:

The number of threads BitBake should run at once (default: 1).

As you may have seen in the usage information, or in the information about .bb files, the BBFILES variable is how the BitBake tool locates its files. This variable is a space-separated list of files that are available, and supports wildcards.

BBFILES = "/path/to/bbfiles/*.bb" With regard to dependencies, it expects the .bb to define a DEPENDS variable, which contains a space separated list of “package names”, which themselves are the PN variable. The PN variable is, in general, set to a component of the .bb filename by default.

a.bb: PN = "package-a" DEPENDS += "package-b" b.bb: PN = "package-b"

This example shows the usage of the PROVIDES variable, which allows a given .bb to specify what functionality it provides. package1.bb: PROVIDES += "virtual/package" package2.bb: DEPENDS += "virtual/package" package3.bb: PROVIDES += "virtual/package" As you can see, we have two different recipes that provide the same functionality (virtual/package). Clearly, there needs to be a way for the person running BitBake to control which of those providers gets used. There is, indeed, such a way. The following would go into a .conf file, to select package1: PREFERRED_PROVIDER_virtual/package = "package1"

When there are multiple “versions” of a given package, BitBake defaults to selecting the most recent version, unless otherwise specified. If the .bb in question has a DEFAULT_PREFERENCE set lower than the other recipes (default is 0), then it will not be selected. This allows the person or persons maintaining the repository of .bb files to specify their preference for the default selected version. In addition, the user can specify their preferred version. If the first .bb is named a_1.1.bb, then the PN variable will be set to “a”, and the PV variable will be set to 1.1. If we then have an a_1.2.bb, BitBake will choose 1.2 by default. However, if we define the following variable in a .conf file that BitBake parses, we can change that. PREFERRED_VERSION_a = "1.1"

Recipe file collections exist to allow the user to have multiple repositories of .bb files that contain the same exact package. For example, one could easily use them to make one's own local copy of an upstream repository, but with custom modifications that one does not want upstream. Here is an example: BBFILES = "/stuff/openembedded/*/*.bb /stuff/openembedded.modified/*/*.bb" BBFILE_COLLECTIONS = "upstream local" BBFILE_PATTERN_upstream = "^/stuff/openembedded/" BBFILE_PATTERN_local = "^/stuff/openembedded.modified/" BBFILE_PRIORITY_upstream = "5" BBFILE_PRIORITY_local = "10"