[PATCH] x86_64: Don't sync APIC ARBs on P4s.

Merged from i386
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/apic.c

@@ -225,6 +225,11 @@ int __init verify_local_APIC(void)
 
 void __init sync_Arb_IDs(void)
 {
+	/* Unsupported on P4 - see Intel Dev. Manual Vol. 3, Ch. 8.6.1 */
+	unsigned int ver = GET_APIC_VERSION(apic_read(APIC_LVR));
+	if (ver >= 0x14)	/* P4 or higher */
+		return;
+
 	/*
 	 * Wait for idle.
 	 */