x86_64 write apic id fix From: Vivek Goyal 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 Signed-off-by: Andi Kleen Index: linux/arch/x86_64/kernel/apic.c =================================================================== --- linux.orig/arch/x86_64/kernel/apic.c +++ linux/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(); Index: linux/include/asm-x86_64/apicdef.h =================================================================== --- linux.orig/include/asm-x86_64/apicdef.h +++ linux/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)