diff --git a/arch/x86_64/kernel/setup.c b/arch/x86_64/kernel/setup.c
index 28895c0..506f152 100644
--- a/arch/x86_64/kernel/setup.c
+++ b/arch/x86_64/kernel/setup.c
@@ -877,6 +877,7 @@
 static int __init init_amd(struct cpuinfo_x86 *c)
 {
 	int r;
+	unsigned level;
 
 #ifdef CONFIG_SMP
 	unsigned long value;
@@ -899,6 +900,11 @@
 	   3DNow is IDd by bit 31 in extended CPUID (1*32+31) anyway */
 	clear_bit(0*32+31, &c->x86_capability);
 	
+	/* On C+ stepping K8 rep microcode works well for copy/memset */
+	level = cpuid_eax(1);
+	if (c->x86 == 15 && ((level >= 0x0f48 && level < 0x0f50) || level >= 0x0f58))
+		set_bit(X86_FEATURE_REP_GOOD, &c->x86_capability);
+
 	r = get_model_name(c);
 	if (!r) { 
 		switch (c->x86) {