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Re: [Qemu-devel] Pentium Pro Feature Bugs
From: |
Thomas Huth |
Subject: |
Re: [Qemu-devel] Pentium Pro Feature Bugs |
Date: |
Mon, 1 Apr 2019 07:35:50 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.5.0 |
On 01/04/2019 05.36, tedheadster wrote:
> I just noticed this in the code regarding MMX and I wonder if it is correct:
>
> target/i386/cpu.c:
>
> #define PPRO_FEATURES (CPUID_FP87 | CPUID_DE | CPUID_PSE | CPUID_TSC | \
> CPUID_MSR | CPUID_MCE | CPUID_CX8 | CPUID_PGE | CPUID_CMOV | \
> CPUID_PAT | CPUID_FXSR | CPUID_MMX | CPUID_SSE | CPUID_SSE2 | \
> CPUID_PAE | CPUID_SEP | CPUID_APIC)
>
> The problem I see is that the PentiumPro never supported the MMX
> instruction extensions (oddly supported in the the Pentium MMX), nor
> the even later SSE (Pentium III) and SSE2 (Pentium 4) features.
>
> Also, the Pentium Pro never officially supported SYSENTER/SYSEXIT
> (CPUID_SEP), though they originally intended to. Intel discovered
> shortly before the product release that the hardware didn't work
> correctly, so they never documented it as a feature to prevent its
> use.
>
> Should these be removed?
Looking at the output of "qemu-system-x86_64 -cpu help", it seems to me
like QEMU does not emulate the Pention Pro at all. So maybe we should
simply rename that macro to "QEMU32_FEATURES" or something similar?
Thomas