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Subject[PATCH] i386 add Intel PEBS and BTS cpufeature bits and detection
Hello,

Here is a small patch that adds two cpufeature bits to represent
Intel's Precise-Event-Based Sampling (PEBS) and Branch Trace Store
(BTS) features. Those features can be found on Intel P4 and Core 2
processors among others and can be used by perfmon.

changelog:
- add CPU_FEATURE_PEBS and CPU_FEATURE_BTS
- add feature detection code

signed-off-by: stephane eranian <eranian@hpl.hp.com>

diff --exclude=.git -urNp linux-2.6.orig/arch/i386/kernel/cpu/intel.c linux-2.6.base/arch/i386/kernel/cpu/intel.c
--- linux-2.6.orig/arch/i386/kernel/cpu/intel.c 2006-10-17 05:33:35.000000000 -0700
+++ linux-2.6.base/arch/i386/kernel/cpu/intel.c 2006-11-15 08:12:22.000000000 -0800
@@ -97,7 +97,7 @@ static int __cpuinit num_cpu_cores(struc

static void __cpuinit init_intel(struct cpuinfo_x86 *c)
{
- unsigned int l2 = 0;
+ unsigned int l1, l2 = 0;
char *p = NULL;

#ifdef CONFIG_X86_F00F_BUG
@@ -195,6 +195,14 @@ static void __cpuinit init_intel(struct
if ((c->x86 == 0xf && c->x86_model >= 0x03) ||
(c->x86 == 0x6 && c->x86_model >= 0x0e))
set_bit(X86_FEATURE_CONSTANT_TSC, c->x86_capability);
+
+ if (cpu_has_ds) {
+ rdmsr(MSR_IA32_MISC_ENABLE, l1, l2);
+ if (!(l1 & (1<<11)))
+ set_bit(X86_FEATURE_BTS, c->x86_capability);
+ if (!(l1 & (1<<12)))
+ set_bit(X86_FEATURE_PEBS, c->x86_capability);
+ }
}

diff --exclude=.git -urNp linux-2.6.orig/include/asm-i386/cpufeature.h linux-2.6.base/include/asm-i386/cpufeature.h
--- linux-2.6.orig/include/asm-i386/cpufeature.h 2006-10-17 05:33:40.000000000 -0700
+++ linux-2.6.base/include/asm-i386/cpufeature.h 2006-11-15 08:13:37.000000000 -0800
@@ -73,6 +73,8 @@
#define X86_FEATURE_UP (3*32+ 9) /* smp kernel running on up */
#define X86_FEATURE_FXSAVE_LEAK (3*32+10) /* FXSAVE leaks FOP/FIP/FOP */
#define X86_FEATURE_ARCH_PERFMON (3*32+11) /* Intel Architectural PerfMon */
+#define X86_FEATURE_PEBS (3*32+12) /* Precise-Event Based Sampling */
+#define X86_FEATURE_BTS (3*32+13) /* Branch Trace Store */

/* Intel-defined CPU features, CPUID level 0x00000001 (ecx), word 4 */
#define X86_FEATURE_XMM3 (4*32+ 0) /* Streaming SIMD Extensions-3 */
@@ -134,6 +136,9 @@
#define cpu_has_phe_enabled boot_cpu_has(X86_FEATURE_PHE_EN)
#define cpu_has_pmm boot_cpu_has(X86_FEATURE_PMM)
#define cpu_has_pmm_enabled boot_cpu_has(X86_FEATURE_PMM_EN)
+#define cpu_has_ds boot_cpu_has(X86_FEATURE_DTES)
+#define cpu_has_pebs boot_cpu_has(X86_FEATURE_PEBS)
+#define cpu_has_bts boot_cpu_has(X86_FEATURE_BTS)

#endif /* __ASM_I386_CPUFEATURE_H */

-
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