[PATCH] x86_64: x86_64 write apic id fix

o Apic id is in most significant 8 bits of APIC_ID register. Current code
  is trying to write apic id to least significant 8 bits. This patch fixes
  it.

o This fix enables booting uni kdump capture kernel on a cpu with non-zero
  apic id.

Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 2 insertions, 1 deletions

diff --git a/arch/x86_64/kernel/apic.c b/arch/x86_64/kernel/apic.c
index 628aebf9f9aa..c3239f6c22be 100644
--- a/arch/x86_64/kernel/apic.c
+++ b/arch/x86_64/kernel/apic.c
@@ -1066,7 +1066,7 @@ int __init APIC_init_uniprocessor (void)
         connect_bsp_APIC();
 
         phys_cpu_present_map = physid_mask_of_physid(boot_cpu_id);
-        apic_write_around(APIC_ID, boot_cpu_id);
+        apic_write_around(APIC_ID, SET_APIC_ID(boot_cpu_id));
 
         setup_local_APIC();
 
diff --git a/include/asm-x86_64/apicdef.h b/include/asm-x86_64/apicdef.h
index fb1c99ac669f..decaa2d540e8 100644
--- a/include/asm-x86_64/apicdef.h
+++ b/include/asm-x86_64/apicdef.h
@@ -13,6 +13,7 @@
 #define         APIC_ID         0x20
 #define                 APIC_ID_MASK            (0xFFu<<24)
 #define                 GET_APIC_ID(x)          (((x)>>24)&0xFFu)
+#define                 SET_APIC_ID(x)          (((x)<<24))
 #define         APIC_LVR        0x30
 #define                 APIC_LVR_MASK           0xFF00FF
 #define                 GET_APIC_VERSION(x)     ((x)&0xFFu)