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Subject[PATCH] [x86] Bug fix in P6 Machine check initialization


Make P6 MCA initialization code complaint with guidelines in
IA-32 SDM Vol3. Bank 0 control register should not be set by OS and clear status
registers on all banks on reset.

This will preven false MCE alarms on the systems that has some non-MCE
information left-over in MC0_STATUS on reboot.

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>

Index: linux-2.6.12/arch/i386/kernel/cpu/mcheck/p6.c
===================================================================
--- linux-2.6.12.orig/arch/i386/kernel/cpu/mcheck/p6.c 2005-08-30 11:10:46.000000000 -0700
+++ linux-2.6.12/arch/i386/kernel/cpu/mcheck/p6.c 2005-09-22 15:37:53.653669656 -0700
@@ -103,11 +103,16 @@
wrmsr(MSR_IA32_MCG_CTL, 0xffffffff, 0xffffffff);
nr_mce_banks = l & 0xff;

- /* Don't enable bank 0 on intel P6 cores, it goes bang quickly. */
- for (i=1; i<nr_mce_banks; i++) {
+ /*
+ * Following the example in IA-32 SDM Vol 3:
+ * - MC0_CTL should not be written
+ * - Status registers on all banks should be cleared on reset
+ */
+ for (i=1; i<nr_mce_banks; i++)
wrmsr (MSR_IA32_MC0_CTL+4*i, 0xffffffff, 0xffffffff);
+
+ for (i=0; i<nr_mce_banks; i++)
wrmsr (MSR_IA32_MC0_STATUS+4*i, 0x0, 0x0);
- }

set_in_cr4 (X86_CR4_MCE);
printk (KERN_INFO "Intel machine check reporting enabled on CPU#%d.\n",
-
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