OpenBSD up to 5.9 had errno(2) symlinked to intro(2), describing error codes: https://man.freebsd.org/cgi/man.cgi?query=errno&apropos=0&sektion=2&manpath=OpenB

OpenBSD up to 5.9 had errno(2) symlinked to intro(2), describing error codes: https://man.freebsd.org/cgi/man.cgi?query=errno&apropos=0&sektion=2&manpath=OpenBSD+5.9&arch=default&format=html https://man.freebsd.org/cgi/man.cgi?query=errno&apropos=0&se... Also, your statements about the kernel and libc are OS specific.