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[PATCH] i386: add command line option "local_apic_timer_c2_ok"

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It turned out that it is almost impossible to trust ACPI, BIOS & Co.
regarding the C states. This was the reason to switch the local apic
timer off in C2 state already. OTOH there are sane and well behaving
systems, which get punished by that decision.

Allow the user to confirm that the local apic timer is trustworthy in C2
state. This keeps the default behaviour on the safe side.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Thomas Gleixner
2007-03-23 16:08:01 +01:00
committed by Linus Torvalds
parent 296d93cd02
commit e585bef815
4 changed files with 16 additions and 1 deletions
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3
drivers/acpi/processor_idle.c
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@ -268,6 +268,7 @@ static void acpi_timer_check_state(int state, struct acpi_processor *pr,
struct acpi_processor_cx *cx)
{
struct acpi_processor_power *pwr = &pr->power;
u8 type = local_apic_timer_c2_ok ? ACPI_STATE_C3 : ACPI_STATE_C2;
/*
* Check, if one of the previous states already marked the lapic
@ -276,7 +277,7 @@ static void acpi_timer_check_state(int state, struct acpi_processor *pr,
if (pwr->timer_broadcast_on_state < state)
return;
if (cx->type >= ACPI_STATE_C2)
if (cx->type >= type)
pr->power.timer_broadcast_on_state = state;
}