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ACPI : Create "idle=nomwait" bootparam

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"idle=nomwait" disables the use of the MWAIT
instruction from both C1 (C1_FFH) and deeper (C2C3_FFH)
C-states.

When MWAIT is unavailable, the BIOS and OS generally
negotiate to use the HALT instruction for C1,
and use IO accesses for deeper C-states.

This option is useful for power and performance
comparisons, and also to work around BIOS bugs
where broken MWAIT support is advertised.

http://bugzilla.kernel.org/show_bug.cgi?id=10807
http://bugzilla.kernel.org/show_bug.cgi?id=10914

Signed-off-by: Zhao Yakui <yakui.zhao@intel.com>
Signed-off-by: Li Shaohua <shaohua.li@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
This commit is contained in:
Zhao Yakui
2008-06-24 18:01:09 +08:00
committed by Andi Kleen
parent c1e3b377ad
commit da5e09a1b3
7 changed files with 35 additions and 2 deletions
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1
include/asm-x86/processor.h
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@ -728,6 +728,7 @@ extern void select_idle_routine(const struct cpuinfo_x86 *c);
extern unsigned long boot_option_idle_override;
extern unsigned long idle_halt;
extern unsigned long idle_nomwait;
extern void enable_sep_cpu(void);
extern int sysenter_setup(void);