On Friday 02 February 2007, Heike C. Zimmerer wrote:
> Frank Mehnert <[EMAIL PROTECTED]> writes:
> > On Thursday 01 February 2007, Heike C. Zimmerer wrote:
> >> Achim Hasenmueller <[EMAIL PROTECTED]> writes:
> >> > Looking at your VBox.log, it seems as if your CPU does not support
> >> > CMPXCHG8B. Wonder why Windows refuses to install without it. Maybe it
> >> > doesn't fully recognize the CPU and thinks it's Intel which has to
> >> > have the feature?
> >>
> >> Not sure if they are required.  Looking into it further, I've stumbled
> >> across this bookmark:
> >>
> >> From http://radagast.bglug.ca/epia/epia_howto/x1099.html :
> >>
> >>    The identification issue is that the C3 is identifying itself as
> >>    686. According to the Intel IA32 documentation, this is correct: C3
> >>    does not implement conditional moves*, and do not pretend to
> >>    implement conditional moves. The Intel documentation states that
> >>    you should check before doing conditional moves, and that cmov
> >>    implementation in the processor is optional.
> >
> > I'm a bit confused about that HOWTO since CMOV has nothing todo with
> > CMPXCHG8B. And your CPUID states that the host _has_ CMOV.
>
> Indeed. I took it for granted that they belong to the same capability
> group.
>
> > It is also possible that the installer detects VIA CPUs and expects some
> > other feature is not emulated by the VM, for example look at the CPUID
> > extended attributes at index 0x80000005 and 0x80000006.
>
> As I said, I'm not at all fluent at x86 assembly language.  But after
> having a look at the CPUID spec and then into the VirtualBox log, it
> seems to me that the VIA CPU announces (at 8000_0000_eax) Fn8000_0004
> as its highest available extended CPUID function number, whereas the
> guest receives Fn8000_0006 in this place (plus there's some content in
> there).
>
> Could that be the reason why the XP installer seems to assume a CPU
> type which is different from what it is running on?

Yes, it could. BTW, you switched host and guest: The maximum CPUID index
the guest receives is 0x80000004 while the host CPU reports 0x80000006.
Look at src/VBox/VMM/CPUM.cpp:316 -- you could try to play with these
values.

Kind regards,

Frank
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