From a31bc32760992a2c68f3d6bf7da9f760c0fd7c41 Mon Sep 17 00:00:00 2001 From: Yinghai Lu Date: Fri, 23 Dec 2011 11:01:43 -0800 Subject: x86, x2apic: Allow "nox2apic" to disable x2apic mode setup by BIOS Currently "nox2apic" boot parameter was not enabling x2apic mode if the cpu, kernel are all capable of enabling x2apic mode and the OS handover happened in xapic mode. However If the bios enabled x2apic prior to OS handover, using "nox2apic" boot parameter had no effect. If the boot cpu's apicid is < 255, enable "nox2apic" boot parameter to disable the x2apic mode setup by the bios. This will enable the kernel to fallback to xapic mode and bringup only the cpu's which has apic-id < 255. -v2: fix patch error and two compiling warning make disable_x2apic to be __init Signed-off-by: Yinghai Lu Signed-off-by: Suresh Siddha Link: http://lkml.kernel.org/r/CAE9FiQUeB-3uxJAMiHsz=uPWoFv5Hg1pVepz7aU6YtqOxMC-=Q@mail.gmail.com Signed-off-by: H. Peter Anvin --- arch/x86/include/asm/apic.h | 1 + 1 file changed, 1 insertion(+) (limited to 'arch/x86/include/asm') diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h index a12d57193fef..3ab9bdd87e79 100644 --- a/arch/x86/include/asm/apic.h +++ b/arch/x86/include/asm/apic.h @@ -216,6 +216,7 @@ static inline void x2apic_force_phys(void) { } +#define nox2apic 0 #define x2apic_preenabled 0 #define x2apic_supported() 0 #endif -- cgit v1.2.2