4.2 Parallel Build

While talking about building your source we might as well mention parallel builds here. If you simply run make -j in your package directory, you will notice that make will drop several dependencies (see Section 5) and then start a parallel build. This is actually not the intended behaviour, because of course we would like to keep the dependencies intact. Thus we must only enable parallel build where it is appropriate, for instance, in one sub-directory containing only source files. Therefore, we use the environment variable PL to specify the level of parallelism. You may invoke make like this:

~/src/l4/pkg > make O=\$(HOME)/build-dirs/build-v2 PL=4