Re: FPU-intensive programs crashing with floating point exception on Cyrix MII

["linux-os \(Dick Johnson\)" <linux-os@analogic.com>]

On Wed, 17 Aug 2005, Ondrej Zary wrote:

> My machine (Cyrix MII PR300 CPU, PCPartner TXB820DS board with i430TX
> chipset) exhibits a really weird problem:
> When I run a program that uses FPU, it sometimes crashes with "flaoting
> point exception" - for example, when playing MP3 files using any player.
> Or with Prime95 - http://www.mersenne.org/freesoft.htm - the "torture
> test" does not crash but shows "fatal error" in less than 10 minutes.
> It might be something like this:
> http://lists.suse.com/archive/suse-linux-e/2000-Sep/1080.html
> or this
> http://lists.slug.org.au/archives/slug/2000/11/msg00343.html
>
> The problem appears on 2.4.x kernels and 2.6.x kernels. It works fine in
> Windows 98 - it can play MP3s and run Prime95 for hours without any
> problems.
> I've tracked it down to math_error() in arch/i386/kernel/traps.c and
> "fixed" it (I really don't know anything about FPU programming). The
> patch is attached. It fixes my system - with the patch, I can play MP3s
> fine and Prime95 runs without any problems too.
>
> Does anyone know why these exceptions happen and/or what's the correct
> solution?
>
> --
> Ondrej Zary
>

0x200 is way up into the "condition" codes. There should have never
been an interrupt at all! Your "fix" is as good as you can get.

>

Cheers,
Dick Johnson
Penguin : Linux version 2.6.12 on an i686 machine (5537.79 BogoMips).
Warning : 98.36% of all statistics are fiction.
.
I apologize for the following. I tried to kill it with the above dot :

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