Comment 3 for bug 729932

errno(2) in freebsd-manpages is actually an alias for intro(2). There's still no reason to cross-reference it from a Linux man page that I can see, but you could reduce confusion by specifically cross-referencing intro(2) rather than errno(2). It is confusing, because, according to Linux man page sectioning, section 2 is for system calls, and so a cross-reference to errno(2) implies that there's a system call called errno, which there isn't (not even on FreeBSD!).