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Commit 39427d6e authored by Andi Kleen's avatar Andi Kleen Committed by Linus Torvalds
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i386: Enable CX8/PGE CPUID bits early on VIA C3 



Fix boot failures with the early CPUID checking on VIA C3

Includes fixes from Christian Volkmann

Signed-off-by: default avatarAndi Kleen <ak@suse.de>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 4c1f59d8

arch/i386/kernel/verify_cpu.S

+27 −0
Original line number Diff line number Diff line
@@ -2,6 +2,7 @@ 
   This runs in 16bit mode so that the caller can still use the BIOS

   to output errors on the screen */

#include <asm/cpufeature.h>

#include <asm/msr.h>



verify_cpu:

	pushfl				# Save caller passed flags
@@ -45,6 +46,32 @@ verify_cpu: 
	cmpl	$0x1,%eax

	jb	bad			# no cpuid 1



#if REQUIRED_MASK1 & NEED_CMPXCHG64

	/* Some VIA C3s need magic MSRs to enable CX64. Do this here */

	cmpl	$0x746e6543,%ebx	# Cent

	jne	1f

	cmpl 	$0x48727561,%edx	# aurH

	jne	1f

	cmpl	$0x736c7561,%ecx	# auls

	jne	1f

	movl	$1,%eax			# check model

	cpuid

	movl	%eax,%ebx

	shr	$8,%ebx

	andl	$0xf,%ebx

	cmp	$6,%ebx			# check family == 6

	jne	1f

	shr	$4,%eax

	andl	$0xf,%eax

	cmpl	$6,%eax			# check model >= 6

	jb	1f

	# assume models >= 6 all support this MSR

	movl	$MSR_VIA_FCR,%ecx

	rdmsr

	orl	$((1<<1)|(1<<7)),%eax	# enable CMPXCHG64 and PGE

	wrmsr

1:

#endif

	movl    $0x1,%eax		# Does the cpu have what it takes

	cpuid