From: "Steven J. Hill" <sjhill@realitydiluted.com>
To: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Subject: Re: gcc 3.2.0 bug causes kernel failure
Date: Fri, 05 Mar 2004 11:49:34 -0500 [thread overview]
Message-ID: <4048AF9E.2060401@realitydiluted.com> (raw)
In-Reply-To: <20040305152206.GA21264@linux-mips.org>
Ralf Baechle wrote:
> Me and Steven have tracked down a LTP failure in the capget tests to a
> bug in gcc 3.2.0. Reducing optimization to just -O seems to solve the
> problem. To this point we've found the capget LTP problem with 2.4
> kernel built with 3.2.0; 2.6.3 built with 2.95.4 seems to be ok. We've
> also only tested 32-bit kernels. We'de be interested in test results
> from other configurations, in particular 2.4 kernels built by later 3.2.x
> compiler revisions would be of interest.
>
Further investigation of GCC 3.2.0 compiler optimizations shows that the
'-fschedule-insns' is to blame for incorrect code generation. By adding
the option '-fno-schedule-insns' correct code will be generated. This
was verified with the following instruction schedulings:
-mcpu=r4300 -mips2
-mcpu=r4600 -mips2
-mcpu=r5000 -mips2
All of these exhibit the same failure. They also exhibit the same success
when the above compiler option is used. Thanks again to Ralf for giving
me more ideas to try and verify this. I have not verified that newer
gcc-3.2.x or gcc-3.3 versions fix this problem. Comments and more testing
are welcome. Thanks.
-Steve
next prev parent reply other threads:[~2004-03-05 16:51 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-03-05 15:22 gcc 3.2.0 bug causes kernel failure Ralf Baechle
2004-03-05 16:49 ` Steven J. Hill [this message]
2004-03-05 20:10 ` Steven J. Hill
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