From: Ralf Baechle <ralf@oss.sgi.com>
To: Jun Sun <jsun@mvista.com>
Cc: linux-mips@oss.sgi.com
Subject: Re: FPU emul and segmentation fault bug
Date: Mon, 25 Feb 2002 04:11:54 +0100 [thread overview]
Message-ID: <20020225041154.A2993@dea.linux-mips.net> (raw)
In-Reply-To: <3C76F53D.2C893BC7@mvista.com>; from jsun@mvista.com on Fri, Feb 22, 2002 at 05:49:49PM -0800
On Fri, Feb 22, 2002 at 05:49:49PM -0800, Jun Sun wrote:
> I remember a while back we had a problem with FPU emulation code which causes
> a segmentation fault. (Perhaps another symptom is bus error, but I am not
> 100% sure).
>
> Apparently this problem is fixed in the recent kernel. However, it shows up
> again in SMP mode.
>
> Does anybody remember details of the problem and the fix? I am afraid maybe
> something we did there is not SMP safe.
That's most probably a SMP cache invalidation bug. What happens is that
remote CPUs try to invalidate the same address range as a local CPU as
well without any consideration that the active context of the remote
CPU might be different from the local one. In combination with another
bug this may actually crash the whole system.
Ralf
prev parent reply other threads:[~2002-02-25 4:12 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-02-23 1:49 FPU emul and segmentation fault bug Jun Sun
2002-02-25 3:11 ` Ralf Baechle [this message]
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