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SubjectRe: Bug on 2.6.26 - x86 VIA Nehemiah CentaurHauls processor cannot boot
Andi Kleen wrote:
>
> This was originally supposed to be handled in the early real mode
> head.S code. That is why I put the CPUID checking code in there
> to error out early when you can still print to the console
> using the BIOS functions.
>
> I suspect this regressed when that code was moved to C, because
> now the C compiler generates CMOV early.
>
> How about always building the real mode C code with -march=i386?
> It is not performance critical so that is ok.
>

The real mode code *is* compiled with -march=i386, and in the CMOV case
it will err out with a legible message.

The issue isn't CMOV at all, it's with long NOPs, which don't have a
CPUID bit -- they're supposed to be supported if family >= 6, but some
VIA chips violate that condition.

-hpa


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