Hi,
Thanks Andres, i686 check-world passed with your
atomic-uint64-alignment.patch.
Vladimir Kokovic
Belgrade Serbia, 9.Jan 2015
------- Forwarded message -------
From: "Andres Freund" <and...@2ndquadrant.com>
To: "Heikki Linnakangas" <hlinnakan...@vmware.com>
Cc: "Vladimir Koković" <vladimir.koko...@gmail.com>,
"pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Subject: Re: [HACKERS] make check-world regress failed
Date: Thu, 08 Jan 2015 21:46:35 +0100
On 2014-12-04 16:38:45 +0200, Heikki Linnakangas wrote:
On 11/23/2014 08:37 PM, Vladimir Koković wrote:
>PostgreSQL check-world regress failed with current GIT HEAD on my
Kubuntu
>14.10.
>
>uname -a
>Linux vlD-kuci 3.16.0-24-generic #32-Ubuntu SMP Tue Oct 28 13:13:18 UTC
>2014 i686 athlon i686 GNU/Linux
>
>gdb -d /home/src/postgresql-devel/postgresql-git/postgresql/src -c core
>...
>Loaded symbols for
>/home/src/postgresql-devel/dev-build/src/test/regress/regress.so
>(gdb) bt
>#0 0xb76ecc7c in __kernel_vsyscall ()
>#1 0xb7075577 in __GI_raise (sig=sig@entry=6) at
>../nptl/sysdeps/unix/sysv/linux/raise.c:56
>#2 0xb7076cf3 in __GI_abort () at abort.c:89
>#3 0x084c326a in ?? ()
>#4 0x0a56c3b8 in ?? ()
>#5 0xb76d232f in pg_atomic_init_u64 (ptr=0xbfa16fd4, val=0) at
>/home/src/postgresql-devel/postgresql-git/postgresql/src/include/port/atomics.h:445
>#6 0xb76d50e4 in test_atomic_uint64 () at
>/home/src/postgresql-devel/postgresql-git/postgresql/src/test/regress/regress.c:1022
>#7 0xb76d5756 in test_atomic_ops (fcinfo=0xa57c76c) at
>/home/src/postgresql-devel/postgresql-git/postgresql/src/test/regress/regress.c:1114
>#8 0x0825bfee in ?? ()
>...
Andres, have you had a chance to look at this?
Nope, missed it somehow.
On 32-bit x86, arch-x86.h leaves PG_HAVE_ATOMIC_U64_SUPPORT undefined.
But
generic-gcc.h, which is included later, then defines it.
That's fine. The only reason arch-x86.h implements anything itself is
that that allows older compilers than relying on intrinsics. But
implementing 64bit atomics is too annoying by hand and isn't currently
required.
pg_atomic_init_u64 does AssertPointerAlignment(ptr, 8) on the variable,
but
there is no guarantee that it is 8-bytes aligned on x86.
Hrmpf. Annoying. Gcc for a while claimed that was guaranteed, but, if I
understood the tickets correctly, gave up on that.
Unfortunately we have to rely (IIRC) on that for (quite old) x86s and
some other architectures. It doesn't seem to be a problem on any native
64bit platform, because 64bit variables are 8byte aligned natively
there.
I think it can relatively easily be fixed by something like the
attached. Don't have a pure 32bit environment to test though - the
problem isn't reproducable in a 32bit chroot...
Vladimir, if you apply that patch, do things work for you?
Greetings,
Andres Freund
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