- Write and maintain the toolchain targets - this involves downloading
and building binutils and gcc (please see buildroot or OpenEmebedded for examples of how complex this can be).
Or see http://git.infradead.org/users/segher/buildall.git for an example of how simple it is. This builds toolchains (for pretty much any target arch) without libc support; they can build an OS kernel or a firmware just fine.
Segher