[PATCH] i386: i386 add X86_FEATURE_PEBS and detection

Here is a patch (used by perfmon2) to detect the presence of the Precise Event
Based Sampling (PEBS) feature for i386.  The patch also adds the cpu_has_pebs
macro.

- adds X86_FEATURE_PEBS

- adds cpu_has_pebs to test for X86_FEATURE_PEBS

Signed-off-by: stephane eranian <eranian@hpl.hp.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>

1 files changed, 7 insertions, 1 deletions

diff --git a/arch/i386/kernel/cpu/intel.c b/arch/i386/kernel/cpu/intel.c
index 94a95aa5227e..798c2f617e87 100644
--- a/arch/i386/kernel/cpu/intel.c
+++ b/arch/i386/kernel/cpu/intel.c
@@ -195,8 +195,14 @@ static void __cpuinit init_intel(struct cpuinfo_x86 *c)
         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) {
+                unsigned int l1;
+                rdmsr(MSR_IA32_MISC_ENABLE, l1, l2);
+                if (!(l1 & (1<<12)))
+                        set_bit(X86_FEATURE_PEBS, c->x86_capability);
+        }
+}
 
 static unsigned int __cpuinit intel_size_cache(struct cpuinfo_x86 * c, unsigned int size)
 {