@p >But you should use a smaller one
I should run a proprietary bootloader that doesn't respect my freedom because it's smaller?

Are you kidding me?

>See linux-0.11.tar.gz's include/unistd.h
I am absolutely certain that such internal header file is not compatible with Unix's interfaces, therefore it is nonsense to claim that was "implementing Unix interfaces".

While it was written to be a Unix-kernel-like, it never pretended to be Unix, as a kernel cannot pretend to be an OS, no matter what.