[PATCH] x86-64: 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 Intel 64-bit processors.
The patch also adds the cpu_has_pebs macro.
changelog:
- 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>
diff --git a/arch/x86_64/kernel/setup.c b/arch/x86_64/kernel/setup.c
index fc944b5..619af2e 100644
--- a/arch/x86_64/kernel/setup.c
+++ b/arch/x86_64/kernel/setup.c
@@ -835,6 +835,13 @@
set_bit(X86_FEATURE_ARCH_PERFMON, &c->x86_capability);
}
+ if (cpu_has_ds) {
+ unsigned int l1, l2;
+ rdmsr(MSR_IA32_MISC_ENABLE, l1, l2);
+ if (!(l1 & (1<<12)))
+ set_bit(X86_FEATURE_PEBS, c->x86_capability);
+ }
+
n = c->extended_cpuid_level;
if (n >= 0x80000008) {
unsigned eax = cpuid_eax(0x80000008);