I have finished the stdlib-free implementation. It's available on the linux branch. Most of the new stuff is in these commits:
I have also done some refactoring along the way, most notably the command line argument handling has been changed to not require any core/main.c changes.
The implementation linking to stdlib has been moved to a separate linuxlibc PLATFORM and is now on its own linuxlibc branch.
Details of the implementation will follow in the notes soon.
Josh did a thorough review of the codebase (thanks again!), which resulted in all kinds of changes including asm style, some refactoring and also two bigger new things:
Details coming to notes.
With the issues resolved Josh said pretty much everything essential is done and hence the project is ready for a wider audience. Thus a call for feedback was sent to -devel.