Re: 2.6.22-rc1 does not boot on VIA C3_2 cause of X86_CMPXCHG64

[Dave Jones <davej@redhat.com>]

On Thu, May 17, 2007 at 02:09:16AM +0200, Christian wrote:

 > my small VIA C3_2 box does not boot with 2.6.22-rc1.
 > It even does not uncompress the kernel.
 > 
 > The configuration as M386 M486 works. But M586 + MVIAC3_2
 > does not work.
 > 
 > solution for me, cahnge arch/i386/Kconfig.cpu
 > 
 > --- arch/i386/Kconfig.cpu.before     2007-05-17 01:38:26.000000000 +0200
 > +++ arch/i386/Kconfig.cpu       2007-05-17 00:54:52.000000000 +0200
 > @@ -299,5 +299,5 @@
 > 
 >  config X86_CMPXCHG64
 >         bool
 > -       depends on !M386 && !M486
 > +       depends on !M386 && !M486 && !MVIAC3_2
 >         default y
 > 
 > 
 > The related #ifdef is in ./include/asm-i386/cmpxchg.h
 > May be cmpxchg8b is not supported by VIAC3_2 ?
 > 
 > May be some other non Intel/AMD need to be excluded from X86_CMPXCHG64 ?
 > May be the generic option CONFIG_X86_GENERIC need to switch this off also ?

The C3s all have cx8, but it needs to be enabled in an MSR first.
(See arch/i386/kernel/cpu/centaur.c , search for CX8)

Did we add code that uses cmpxchg8b before identify_cpu() gets run ?
I've not been paying attention to .22rc (busy trying to beat .21 into shape for F7)
so I may have missed something obvious. Andi?

	Dave

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