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252 lines
6.4 KiB
252 lines
6.4 KiB
title "Processor type and stepping detection"
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;++
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;
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; Copyright (c) 1989 Microsoft Corporation
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;
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; Module Name:
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;
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; cpu.asm
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;
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; Abstract:
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;
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; This module implements the assembley code necessary to determine
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; cpu type and stepping information.
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;
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; Author:
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;
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; Shie-Lin Tzong (shielint) 28-Oct-1991.
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;
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; Environment:
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;
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; 80x86
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;
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; Revision History:
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;
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;--
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.586p
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.xlist
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include mac386.inc
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include callconv.inc
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.list
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_TEXT SEGMENT DWORD PUBLIC 'CODE'
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ASSUME DS:FLAT, ES:FLAT, SS:NOTHING, FS:NOTHING, GS:NOTHING
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CR0_AM equ 40000h
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EFLAGS_AC equ 40000h
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subttl "Is386"
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;++
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;
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; BOOLEAN
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; BlIs386(
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; VOID
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; )
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;
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; Routine Description:
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;
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; This function determines whether the processor we're running on
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; is a 386. If not a 386, it is assumed that the processor is
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; a 486 or greater.
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;
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; Arguments:
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;
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; None.
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;
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; Return Value:
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;
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; (al) = 1 - processor is a 386
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; (al) = 0 - processor is a 486 or greater.
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;
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;--
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public _BlIs386@0
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_BlIs386@0 proc
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mov eax,cr0
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push eax ; save current cr0
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and eax,not CR0_AM ; mask out alignment check bit
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mov cr0,eax ; disable alignment check
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pushfd ; save flags
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pushfd ; turn on alignment check bit in
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or dword ptr [esp],EFLAGS_AC ; a copy of the flags register
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popfd ; and try to load flags
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pushfd
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pop ecx ; get new flags into ecx
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popfd ; restore original flags
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pop eax ; restore original cr0
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mov cr0,eax
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xor al,al ; prepare for return, assume not 386
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and ecx,EFLAGS_AC ; did AC bit get set?
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jnz short @f ; yes, we don't have a 386
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inc al ; we have a 386
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@@: ret
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_BlIs386@0 endp
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subttl "IsCpuidPresent"
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;++
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;
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; BOOLEAN
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; BlIsCpuidPresent(
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; VOID
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; )
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;
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; Routine Description:
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;
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; If bit 21 of the EFLAGS register is writable, CPUID is supported on
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; this processor. If not writable, CPUID is not supported.
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;
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; Note: It is expected that this routine is "locked" onto a single
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; processor when run.
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;
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; Arguments:
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;
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; None.
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;
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; Return Value:
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;
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; TRUE if CPUID is supported,
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; FALSE otherwise.
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;
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;--
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EFLAGS_ID equ 200000h ; bit 21
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cPublicProc _BlIsCpuidPresent ,0
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pushfd ; save EFLAGS
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pop ecx ; get current value
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xor ecx, EFLAGS_ID ; flip bit 21
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push ecx ; set flipped value in EFLAGS
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popfd
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pushfd ; read it back again
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pop eax
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xor eax, ecx ; if new value is what we set
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shr eax, 21 ; then these two are the same
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and eax, 1 ; isolate bit 21 (in bit 0)
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xor eax, 1 ; and flip it
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stdRET _BlIsCpuidPresent
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stdENDP _BlIsCpuidPresent
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page
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subttl "GetFeatureBits"
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;++
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;
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; VOID
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; BlGetFeatureBits(
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; VOID
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; )
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;
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; Routine Description:
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;
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; Execute the CPUID instruction to get the feature bits supported
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; by this processor.
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;
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; Arguments:
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;
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; None.
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;
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; Return Value:
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;
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; Returns the set of feature bits supported by this processor or
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; 0 if this processor does not support the CPUID instruction.
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;
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;--
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cPublicProc _BlGetFeatureBits ,0
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stdCall _BlIsCpuidPresent ; Does this processor do CPUID?
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test eax, 1
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jnz short @f ; Jif yes.
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xor eax, eax ; No, return 0.
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stdRet _BlGetFeatureBits
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@@: mov eax, 1 ; CPUID function 1 gets feature bits.
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push ebx ; save ebx
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cpuid ; execute
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;
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; Due to a bug in NT 4, some processors report that they do
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; not support cmpxchg8b even though they do. Win2K doesn't
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; care but cmpxchg8b is a requirement for Whistler.
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;
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; Check to see if this is one of those processors and if we
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; have been told by the processor manufacturer how to reenable
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; cmpxchg8b, do so.
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;
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test edx, 0100h ; is cmpxchg8b present?
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jnz short gfb90 ; yes, skip
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;
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; cmpxchg8b not present, check for recognized processor
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;
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push eax ; save Family, Model, Stepping
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mov eax, 0
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cpuid
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pop eax
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cmp ebx, 0746e6543h ; Cyrix III = 'CentaurHauls'
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jnz short gfb30
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cmp edx, 048727561h
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jnz short gfb80
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cmp ecx, 0736c7561h
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jnz short gfb80
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cmp eax, 0600h ; consider Cyrix III F/M/S 600 and above
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;
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; Cyrix (Centaur) Set MSR 1107h bit 1 to 1.
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;
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mov ecx, 01107h
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jae gfb20
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cmp eax, 0500h ; consider IDT/Centaur F/M/S 500 and above
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jb short gfb80
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;
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; Centaur family 5, set MSR 107h bit 1 to 1.
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;
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mov ecx, 0107h
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gfb20: rdmsr
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or eax, 2
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wrmsr
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jmp short gfb80
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gfb30: cmp ebx, 0756e6547h ; Transmeta = 'GenuineTMx86'
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jnz short gfb80
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cmp edx, 054656e69h
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jnz short gfb80
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cmp ecx, 03638784dh
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jnz short gfb80
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cmp eax, 0542h ; consider Transmeta F/M/S 542 and above
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jb short gfb80
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;
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; Transmeta MSR 80860004h is a mask applied to the feature bits.
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;
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mov ecx, 080860004h
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rdmsr
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or eax, 0100h
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wrmsr
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gfb80: mov eax, 1 ; reexecute CPUID function 1
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cpuid
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gfb90: mov eax, edx ; return feature bits
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pop ebx ; restore ebx, esi
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stdRET _BlGetFeatureBits
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stdENDP _BlGetFeatureBits
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_TEXT ends
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end
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