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Re: [Qemu-devel] x86 system and x86-64 system emulation
From: |
Antony T Curtis |
Subject: |
Re: [Qemu-devel] x86 system and x86-64 system emulation |
Date: |
Fri, 01 Apr 2005 20:51:42 +0100 |
On Fri, 2005-04-01 at 20:29 +0100, Natalia Portillo wrote:
> Hi!
>
> I've just tested a CPU identification program I've made, under QEMU
> (x86 and x86_64 guests).
>
> In QEMU (x86 guest), CPU says it is a "GenuineIntel" Pentium II (family
> 6, model 3, stepping 3), but following isn't in concordance:
> Pentium II doesn't support nor SSE nor SSE2 and as far as I know also
> doesn't support FXSAVE/FXSTOR operands, and supports Virtual-86 Mode
> Enhacement.
> I think that the CPU model information should be updated, or, doing as
> VirtualPC, made it to be a "GenuineQEMU" CPU instead of a
> "GenuineIntel".
>
> In the QEMU (x86-64 guest), CPU says it is a monoprocessor
> "AuthenticAMD" Athlon (family 6, model 2, stepping 3) in standard level
> and in extended level it says it is a multiprocessor non-existent
> "AuthenticAMD" processor (family B, model F, stepping D), and that it
> is an enginering sample.
>
> According to AMD64 Architecture Programmer's Manual, Volume 3, order
> #24594, and to AMD Processor Recognition Application Note, order
> #20734, it should inform of family F in standard and extended level,
> and have an 8-bit brand id in the standard level or an 12-bit brand id
> in the extended level (but not both) informing the exact model of
> processor.
>
> Also there is lacking emulation of 3DNow!, AMD extensions to MMX, a
> more features that is expected every x86-64 processor have.
I don't think Intel's EM64T offering will support 3DNow! - so that would
be a very poor assumption to make, given that the two are supposed to be
largely compatible technologies.
But I would support the idea of returning some different CPUID string -
perhaps something lite "QEMUSimulate" or some other 12-character
sequence.
--
Antony T Curtis, BSc. UNIX, Linux, *BSD, Networking
address@hidden C++, J2EE, Perl, MySQL, Apache
IT Consultancy.