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Diffstat (limited to 'arch/i386/kernel/verify_cpu.S')
-rw-r--r--arch/i386/kernel/verify_cpu.S27
1 files changed, 27 insertions, 0 deletions
diff --git a/arch/i386/kernel/verify_cpu.S b/arch/i386/kernel/verify_cpu.S
index b2a9d80b642..f1d1eacf4ab 100644
--- a/arch/i386/kernel/verify_cpu.S
+++ b/arch/i386/kernel/verify_cpu.S
@@ -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