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Colin King 10-06-2010 02:46 PM

SRU: Fix CPU feature detection to stop stack dump
From: Colin Ian King <>

BugLink: and

SRU Justification:

Impact: Booting and suspend/resuming causes an kernel warning and a
subsequent kernel stack dump on some machines with CPU features
such as ARAT.

Fix: Some CPU features such as ARAT are needed in early boot so
that x86_init function pointers can be set up properly. Also the
CPU feature detection code has to be re-run after uncapping the CPUID

Testcase: Without the patches, booting and suspend/resuming causes the
error: WARNING: at /build/buildd/linux-maverick-2.6.35/arch/x86/include
/asm/processor.h:1005 read_measured_perf_ctrs+0x6c/0x80(), and a kernel
stack dump. With the patches, boot and resume don't get produce the warning
or stack dump.

This is a cherrypick of upstream commits:
d900329e20f4476db6461752accebcf7935a8055 and

H. Peter Anvin (1):
x86, cpu: After uncapping CPUID, re-run CPU feature detection

Jacob Pan (1):
x86: detect scattered cpuid features earlier

arch/x86/kernel/cpu/common.c | 4 ++--
arch/x86/kernel/cpu/cpu.h | 1 +
arch/x86/kernel/cpu/intel.c | 1 +
3 files changed, 4 insertions(+), 2 deletions(-)

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