Mastering Embedded Linux Programming - Second Edition

Overlays

An overlay is simply a directory structure that is copied over the top of the Buildroot root filesystem at a late stage in the build process. It can contain executables, libraries, and anything else you may want to include. Note that any compiled code must be compatible with the libraries deployed at runtime, which, in turn, means that it must be compiled with the same toolchain that Buildroot uses. Using the Buildroot toolchain is quite easy. Just add it to PATH:

$ PATH=<path_to_buildroot>/output/host/usr/bin:$PATH

The prefix for the toolchain is <ARCH>-linux-. So, to compile a simple program, you would do something like this:

$ PATH=/home/chris/buildroot/output/host/usr/bin:$PATH$ arm-linux-gcc helloworld.c -o helloworld