4.3.1. Finding the Temporary Source Code

During a build, the unpacked temporary source code used by recipes to build packages is available in the Build Directory as defined by the S variable. Below is the default value for the S variable as defined in the meta/conf/bitbake.conf configuration file in the Source Directory:

     S = "${WORKDIR}/${BP}"
            

You should be aware that many recipes override the S variable. For example, recipes that fetch their source from Git usually set S to ${WORKDIR}/git.

Note

The BP represents the base recipe name, which consists of the name and version:
     BP = "${BPN}-${PV}"
                

The path to the work directory for the recipe (WORKDIR) is defined as follows:

     ${TMPDIR}/work/${MULTIMACH_TARGET_SYS}/${PN}/${EXTENDPE}${PV}-${PR}
            

The actual directory depends on several things:

As an example, assume a Source Directory top-level folder name poky, a default Build Directory at poky/build, and a qemux86-poky-linux machine target system. Furthermore, suppose your recipe is named foo_1.3.0-r0.bb. In this case, the work directory the build system uses to build the package would be as follows:

     poky/build/tmp/work/qemux86-poky-linux/foo/1.3.0-r0
            

Now that you know where to locate the directory that has the temporary source code, you can use a Quilt or Git workflow to make your edits, test the changes, and preserve the changes in the form of patches.