Bug#657810: <sys/syscall.h> and <sys/errno.h>

[Petr Salinger <Petr.Salinger@seznam.cz>]

> kfreebsd-kernel-headers 0.70 includes properly patched versions of
> <sys/syscall.h> and <sys/errno.h> which could be used to compile glibc.
>
> Please consider using those instead of the in-tree copies. A patch for
> <bits/errno.h> is attached. <sys/syscall.h> can be used directly.

No, the  <bits/errno.h> have to be part of eglibc,
you can silently break ABI, by changing errno.h.
In fact, due to changes of ELAST it just happened, see
glibc-ports/kfreebsd/Versions and lines
  # The comment lines with "#errlist-compat" are magic; see errlist-compat.awk.
  # When you get an error from errlist-compat.awk, you need to add a new
    #errlist-compat     87
    #errlist-compat     93
    #errlist-compat 94

The <sys/syscall.h> problem is similar,  FreeBSD upstream sometimes 
changes ABI of a syscall, it usually gives the new number for same syscall 
name. The eglibc have to know which one is used, i.e. the exact interface.
See i.e. mmap.c. Again, silent upgrade of sys/syscall.h might be disaster.

Petr