[Bug sanitizer/57316] [4.8 regression] build failure in libsanitizer

["PHHargrove at lbl dot gov" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57316

--- Comment #3 from Paul H. Hargrove <PHHargrove at lbl dot gov> ---
(In reply to Kostya Serebryany from comment #1)
> Sorry for the breakages, but we are unable to monitor build failures on old
> kernels unless someone sets up a regular testing (build bot) with such kernels
> for upstream code.

This error is from a private "build bot" I've now got set up to perform daily
builds of the gupc branch in SVN (see http://gcc.gnu.org/projects/gupc.html). 
As changes are merged from the trunk to that branch I will notice any build
failures and I report them to the GCC Bugzilla if/when I can reproduce them in
the trunk or recent snapshot (eg bug 55989) or in a release (as with this bug).
 Otherwise they are reported to the GUPC team.

I am configuring with --disable-libsanitizer right now, but will remove that
when/if this bug is resolved such that I can build again.


(In reply to Jakub Jelinek from comment #2)
> If you don't have __NR_exit_group, your kernel very likely doesn't have the
> rest of NPTL support either (so e.g. __NR_futex), so I'm surprised this is
> the only error.

This is an old Red Hat "2.4.21-60.ELsmp" kernel that contains various bits that
Red Hat backported.  So, the unistd.h has __NR_fuxtex but not __NR_exit_group. 
I can't say for sure that futex works, however, as there is no NPTL version of
libpthread on the system.

For my own purposes, there is no need to make libsanitizer work on this
platform.  So, if that is not possible I'd like to see configure probe for each
of the syscall numbers (and prctl constants as in bug 55989) and then
automatically disable building the sanitizer code if any are missing.  I don't
like current the build-is-broken-by-default situation.