Re: Cyrix 6x86 Comma Bug 2.6

From: Denis Vlasenko
Date: Mon Dec 20 2004 - 17:27:47 EST

On Saturday 18 December 2004 13:52, Matthias-Christian Ott wrote:
> Hi!
> I have some problems with my Cyrix cpu it stop some times and ugly
> tokens appear on the screen. Is the Comma Bug the reason (I test the
> hdd, memory and pci cards -- they are all ok)? Is the comma bug "fixed"?
> If not so, how to do this?

It is very unlikely that you see "Coma" bug. It can be triggered only
by deliberately coded tight endless loop. "Ugly tokens on the screen"
suggest that you see something else.

arch/i386/kernel/cpu/mtrr/changelog says:
19990218 ZoltАn BЖszЖrmИnyi <zboszor@xxxxxxxxxxxxxxxx>
Remove Cyrix "coma bug" workaround from here.
Moved to linux/arch/i386/kernel/setup.c and

but neither of those files mention "coma"...

PS: "coma" bug won't trigger if automatic locking of
xchg insn is disabled (yes, Cyrix can be configured to do this).
This shall be done for performance reasons too.
No SMP dangers since Cyrix CPUs aren't used in SMP...

So grep the source / google Inet for this if you are still interested.

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