From fb209bd891645bb87b9618b724f0b4928e0df3de Mon Sep 17 00:00:00 2001 From: Yinghai Lu Date: Wed, 21 Dec 2011 17:45:17 -0800 Subject: x86, x2apic: Fallback to xapic when BIOS doesn't setup interrupt-remapping On some of the recent Intel SNB platforms, by default bios is pre-enabling x2apic mode in the cpu with out setting up interrupt-remapping. This case was resulting in the kernel to panic as the cpu is already in x2apic mode but the OS was not able to enable interrupt-remapping (which is a pre-req for using x2apic capability). On these platforms all the apic-ids are < 255 and the kernel can fallback to xapic mode if the bios has not enabled interrupt-remapping (which is mostly the case if the bios has not exported interrupt-remapping tables to the OS). Reported-by: Berck E. Nash Signed-off-by: Yinghai Lu Link: http://lkml.kernel.org/r/20111222014632.600418637@sbsiddha-desk.sc.intel.com Signed-off-by: Suresh Siddha Signed-off-by: H. Peter Anvin --- arch/x86/include/asm/apicdef.h | 1 + 1 file changed, 1 insertion(+) (limited to 'arch/x86/include/asm/apicdef.h') diff --git a/arch/x86/include/asm/apicdef.h b/arch/x86/include/asm/apicdef.h index 3925d8007864..134bba00df09 100644 --- a/arch/x86/include/asm/apicdef.h +++ b/arch/x86/include/asm/apicdef.h @@ -144,6 +144,7 @@ #define APIC_BASE (fix_to_virt(FIX_APIC_BASE)) #define APIC_BASE_MSR 0x800 +#define XAPIC_ENABLE (1UL << 11) #define X2APIC_ENABLE (1UL << 10) #ifdef CONFIG_X86_32 -- cgit v1.2.3