diff --git a/arch/x86_64/kernel/setup.c b/arch/x86_64/kernel/setup.c
index eb6524f..d16f7c2 100644
--- a/arch/x86_64/kernel/setup.c
+++ b/arch/x86_64/kernel/setup.c
@@ -806,6 +806,7 @@ void __cpuinit early_identify_cpu(struct cpuinfo_x86 *c)
 			c->x86_model += ((tfms >> 16) & 0xF) << 4;
 		if (c->x86_capability[0] & (1<<19)) 
 			c->x86_clflush_size = ((misc >> 8) & 0xff) * 8;
+		c->extended_cpuid_level = cpuid_eax(0x80000000);
 	} else {
 		/* Have CPUID level 0 only - unheard of */
 		c->x86 = 4;
@@ -814,6 +815,12 @@ void __cpuinit early_identify_cpu(struct cpuinfo_x86 *c)
 #ifdef CONFIG_SMP
 	c->phys_proc_id = (cpuid_ebx(1) >> 24) & 0xff;
 #endif
+
+	/* power flags are 8000_0007 edx. Bit 8 is constant TSC */
+	if ((c->x86_vendor == X86_VENDOR_AMD) &&
+	    (c->extended_cpuid_level >= 0x80000007) &&
+	    (cpuid_edx(0x80000007) & (1<<8)))
+		set_bit(X86_FEATURE_CONSTANT_TSC, &c->x86_capability);
 }
 
 /*