i386: fix 4 bit apicid assumption of mach-default

Fix get_apic_id() in mach-default, so that it uses 8 bits incase of
xAPIC case and 4 bits for legacy APIC case.

This fixes the i386 kernel assumption that apic id is less than 16 for
xAPIC platforms with 8 cpus or less and makes the kernel boot on such
platforms.

[ tglx: arch/x86 adaptation ]

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Andi Kleen <ak@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 7 insertions, 1 deletions

diff --git a/include/asm-x86/mach-default/mach_apicdef.h b/include/asm-x86/mach-default/mach_apicdef.h
index 7bcb350c3ee8..ae9841319094 100644
--- a/include/asm-x86/mach-default/mach_apicdef.h
+++ b/include/asm-x86/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)