From: Geoff Gustafson <grgustaf@redhat.com>
Date: Tue, 18 Mar 2008 15:59:46 -0400
Subject: [x86] fix 4 bit apicid assumption
Message-id: 20080318195946.GA17749@samurai.boston.redhat.com
O-Subject: [RHEL5.2] i386: fix 4 bit apicid assumption (bz 437820)
Bugzilla: 437820

HP reported that on a new Thurley dual-socket system, if they installed only
one chip, the i386 kernel boots if it's one one socket, but not if it's in the
other. Intel tracked this down to needing >4-bit apic ids. This patch follows
upstream to extend them to 8 bits.

HP took my test kernels and verified the fix.

Please ACK.

- Geoff

Acked-by: Brian Maly <bmaly@redhat.com>
Acked-by: Neil Horman <nhorman@redhat.com>
Acked-by: Alan Cox <alan@redhat.com>

diff --git a/include/asm-i386/mach-default/mach_apicdef.h b/include/asm-i386/mach-default/mach_apicdef.h
index 7bcb350..ae98413 100644
--- a/include/asm-i386/mach-default/mach_apicdef.h
+++ b/include/asm-i386/mach-default/mach_apicdef.h
@@ -1,11 +1,17 @@
 #ifndef __ASM_MACH_APICDEF_H
 #define __ASM_MACH_APICDEF_H
 
+#include <asm/apic.h>
+
 #define		APIC_ID_MASK		(0xF<<24)
 
 static inline unsigned get_apic_id(unsigned long x) 
 { 
-	return (((x)>>24)&0xF);
+	unsigned int ver = GET_APIC_VERSION(apic_read(APIC_LVR));
+	if (APIC_XAPIC(ver))
+		return (((x)>>24)&0xFF);
+	else
+		return (((x)>>24)&0xF);
 } 
 
 #define		GET_APIC_ID(x)	get_apic_id(x)