| GNU/Linux implemented Unix without working with proprietary source code from AT&T. Those people documented their stuff thoroughly and even created international standards. A good many of the Linux system calls and glibc functions are documented by POSIX. That doesn't cover 100%. We can start by looking here: https://www.kernel.org/doc/ The Linux man pages project covers system calls: http://man7.org/linux/man-pages/dir_section_2.html Many of these don't correspond to anything in POSIX, or not directly, so this documentation is crucial to anyone wanting to replicate Linux. Microsoft seems to have done such a thing: https://en.wikipedia.org/wiki/Windows_Subsystem_for_Linux "WSL provides a Linux-compatible kernel interface developed by Microsoft (containing no Linux kernel code) [...]" However, in all likelihood, they peeked at Linux code here and there. |