x86 ACPI: Add support for Always Running APIC timer

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Add support for Always Running APIC timer, CPUID_0x6_EAX_Bit2.
This bit means the APIC timer continues to run even when CPU is
in deep C-states.

The advantage is that we can use LAPIC timer on these CPUs
always, and there is no need for "slow to read and program"
external timers (HPET/PIT) and the timer broadcast logic
and related code in C-state entry and exit.

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Acked-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Len Brown <len.brown@intel.com>

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Venkatesh Pallipadi 2009-04-06 18:51:29 -07:00 • committed by Len Brown

parent 577c9c456f

commit db954b5898

4 changed files with 11 additions and 0 deletions

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1

arch/x86/include/asm/cpufeature.h

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6

arch/x86/kernel/apic/apic.c

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1

arch/x86/kernel/cpu/addon_cpuid_features.c

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3

drivers/acpi/processor_idle.c

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