We currently have

FAIL: mach/check-abi-libmachuser
FAIL: hurd/check-abi-libhurduser

because the abilist files are empty.

See http://sourceware.org/ml/libc-alpha/2018-04/msg00013.html :

“
> These actually depend on
>   .defs files in gnumach and hurd, so we can't really define ABI files.

Depend in what way?  Are you saying they export different symbols
depending on the versions of gnumach and hurd glibc is built with?  How
are symbol versions for such extra symbols determined - based on gnumach
and hurd versions instead of glibc versions?

It's clearly desirable to be able to make sure that old symbol versions
don't change.  But if the contents of those versions are determined by
gnumach and hurd, maybe those packages need to install ABI baselines for
the glibc tests (or something like that).

The nearest analogue I see in glibc for systems using the Linux kernel
(without more information on how the gnumach/hurd dependency works) is the
syscall lists - where we have a list in glibc of all possible syscall
names (sysdeps/unix/sysv/linux/syscall-names.list), and a test will fail
if the kernel has additional syscalls and is not newer than the version
listed in that list (so using a different kernel version does not result
in test failures, but the test is fully effective if the listed kernel
version or an older kernel version is used).
”