From: Jacob Pan on
Check hlt instruction was targeted for some older CPUs. It is an expensive
operation in that it takes 4 ticks to break out the check. We can avoid
such check completely for newer x86 cpus ( family > 5).
http://lkml.org/lkml/2010/5/7/395

Signed-off-by: Jacob Pan <jacob.jun.pan(a)linux.intel.com>
---
arch/x86/kernel/cpu/bugs.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 01a2652..36d9bcf 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -86,7 +86,7 @@ static void __init check_fpu(void)

static void __init check_hlt(void)
{
- if (paravirt_enabled())
+ if (paravirt_enabled() || boot_cpu_data.x86 > 5)
return;

printk(KERN_INFO "Checking 'hlt' instruction... ");
--
1.6.3.3

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