[PATCH 3/4] i386: add the X86_FEATURE_SYNC_RDTSC flag

[Joerg Roedel]

From: Joerg Roedel <joerg.roedel@xxxxxxx>

This patch adds the  X86_FEATURE_SYNC_RDTSC to the i386 architecture.
This is very helpfull to simplify the get_cycles_sync() function and
remove the #ifdefs from it.

Signed-off-by: Joerg Roedel <joerg.roedel@xxxxxxx>

-- 
Joerg Roedel
Operating System Research Center
AMD Saxony LLC & Co. KG
diff --git a/arch/i386/kernel/cpu/amd.c b/arch/i386/kernel/cpu/amd.c
index 41cfea5..11f5730 100644
--- a/arch/i386/kernel/cpu/amd.c
+++ b/arch/i386/kernel/cpu/amd.c
@@ -241,6 +241,8 @@ static void __cpuinit init_amd(struct cpuinfo_x86 *c)
 
 	if (cpuid_eax(0x80000000) >= 0x80000006)
 		num_cache_leaves = 3;
+
+	clear_bit(X86_FEATURE_SYNC_RDTSC, c->x86_capability);
 }
 
 static unsigned int __cpuinit amd_size_cache(struct cpuinfo_x86 * c, unsigned int size)
diff --git a/arch/i386/kernel/cpu/intel.c b/arch/i386/kernel/cpu/intel.c
index 56fe265..403a495 100644
--- a/arch/i386/kernel/cpu/intel.c
+++ b/arch/i386/kernel/cpu/intel.c
@@ -188,8 +188,11 @@ static void __cpuinit init_intel(struct cpuinfo_x86 *c)
 	}
 #endif
 
-	if (c->x86 == 15)
+	if (c->x86 == 15) {
 		set_bit(X86_FEATURE_P4, c->x86_capability);
+		set_bit(X86_FEATURE_SYNC_RDTSC, c->x86_capability);
+	} else
+		clear_bit(X86_FEATURE_SYNC_RDTSC, c->x86_capability);
 	if (c->x86 == 6) 
 		set_bit(X86_FEATURE_P3, c->x86_capability);
 	if ((c->x86 == 0xf && c->x86_model >= 0x03) ||
diff --git a/include/asm-i386/cpufeature.h b/include/asm-i386/cpufeature.h
index 3f92b94..a9f1f01 100644
--- a/include/asm-i386/cpufeature.h
+++ b/include/asm-i386/cpufeature.h
@@ -75,6 +76,7 @@
 #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 */
+#define X86_FEATURE_SYNC_RDTSC  (3*32+14)  /* RDTSC is serializing */
 
 /* Intel-defined CPU features, CPUID level 0x00000001 (ecx), word 4 */
 #define X86_FEATURE_XMM3	(4*32+ 0) /* Streaming SIMD Extensions-3 */