* FPU emul and segmentation fault bug
@ 2002-02-23 1:49 Jun Sun
2002-02-25 3:11 ` Ralf Baechle
0 siblings, 1 reply; 2+ messages in thread
From: Jun Sun @ 2002-02-23 1:49 UTC (permalink / raw)
To: linux-mips
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.
Thanks.
Jun
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: FPU emul and segmentation fault bug
2002-02-23 1:49 FPU emul and segmentation fault bug Jun Sun
@ 2002-02-25 3:11 ` Ralf Baechle
0 siblings, 0 replies; 2+ messages in thread
From: Ralf Baechle @ 2002-02-25 3:11 UTC (permalink / raw)
To: Jun Sun; +Cc: linux-mips
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
^ permalink raw reply [flat|nested] 2+ messages in thread
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