From f44d9efd3510776216938fef84adc99cc0e12412 Mon Sep 17 00:00:00 2001
From: Ingo Molnar <mingo@elte.hu>
Date: Mon, 26 Nov 2007 20:42:20 +0100
Subject: [PATCH] x86: fix APIC related bootup crash on Athlon XP CPUs

warmbloodedcreature@gmail.com reported that an APIC-enabled
Asus a7v8x-x with an Athlon XP reboots early in the bootup:

   http://bugzilla.kernel.org/show_bug.cgi?id=8723

after a long marathon of spontaneous-reboot debugging, it turns
out to be caused by sync_Arb_ids(). AMD CPUs never really needed
this sequence anyway, so just return early if we meet an AMD CPU.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 arch/x86/kernel/apic_32.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/apic_32.c b/arch/x86/kernel/apic_32.c
index 08b07c176962f..96986b46bc856 100644
--- a/arch/x86/kernel/apic_32.c
+++ b/arch/x86/kernel/apic_32.c
@@ -789,7 +789,7 @@ void __init sync_Arb_IDs(void)
 	 * Unsupported on P4 - see Intel Dev. Manual Vol. 3, Ch. 8.6.1 And not
 	 * needed on AMD.
 	 */
-	if (modern_apic())
+	if (modern_apic() || boot_cpu_data.x86_vendor == X86_VENDOR_AMD)
 		return;
 	/*
 	 * Wait for idle.
-- 
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