[PATCH] x86_64: Hack to disable clustered mode on AMD systems

Hack to disable clustered mode on AMD systems

Make sure AMD big flat apic mode is not confused with clustered APIC 
mode. Ugly hack, but no better way found.
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/x86_64/kernel/genapic.c

@@ -41,6 +41,12 @@ void __init clustered_apic_check(void)
 	u8 id;
 	u8 cluster_cnt[NUM_APIC_CLUSTERS];
 
+	if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD) {
+		/* AMD always uses flat mode right now */
+		genapic = &apic_flat;
+		goto print;
+	}
+
 	memset(cluster_cnt, 0, sizeof(cluster_cnt));
 
 	for (i = 0; i < NR_CPUS; i++) {
@@ -71,6 +77,7 @@ void __init clustered_apic_check(void)
 	else
 		genapic = &apic_cluster;
 
+print:
 	printk(KERN_INFO "Setting APIC routing to %s\n", genapic->name);
 }