From: Ralf Baechle <ralf@oss.sgi.com>
To: "Maciej W. Rozycki" <macro@ds2.pg.gda.pl>
Cc: linux-mips@fnet.fr, linux-mips@oss.sgi.com
Subject: Re: [patch] linux 2.4.9: Bad code in xchg_u32()
Date: Wed, 17 Oct 2001 00:29:47 +0200 [thread overview]
Message-ID: <20011017002947.A19789@dea.linux-mips.net> (raw)
In-Reply-To: <Pine.GSO.3.96.1011016161735.19676E-100000@delta.ds2.pg.gda.pl>; from macro@ds2.pg.gda.pl on Tue, Oct 16, 2001 at 07:06:40PM +0200
On Tue, Oct 16, 2001 at 07:06:40PM +0200, Maciej W. Rozycki wrote:
>
> Unfortunately, gcc 2.95.3 doesn't want to accept a "=R" output constraint
> here so I had to use "=m". It looks like a bug in gcc. Until it is fixed
> the "R" input constraint here is sufficient for gcc to know it has m
> already available in one of registers. I added ".set nomacro" to make
> sure the second ll fits in the BDS as well.
I've added the "memory" clobber back; xchg() is expected to imply a memory
barrier.
"R" indeed seems to be fishy; I can't compile the kernel if I remove
the volatile from the first argument of xchg_u32(). I'd feel safer if
we could use "m" until we can be sure "R" works fine.
Ralf
next prev parent reply other threads:[~2001-10-16 22:37 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-10-16 17:06 [patch] linux 2.4.9: Bad code in xchg_u32() Maciej W. Rozycki
2001-10-16 22:29 ` Ralf Baechle [this message]
2001-10-16 22:49 ` Jun Sun
2001-10-17 0:57 ` Ralf Baechle
2001-10-17 11:07 ` Maciej W. Rozycki
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