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

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>

1 files changed, 3 insertions, 0 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index e39ab0c99fbb..09640a8f7ceb 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -780,6 +780,9 @@ and is between 256 and 4096 characters. It is defined in the file
         lapic           [IA-32,APIC] Enable the local APIC even if BIOS
                         disabled it.
 
+        lapic_timer_c2_ok       [IA-32,APIC] trust the local apic timer in
+                        C2 power state.
+
         lasi=           [HW,SCSI] PARISC LASI driver for the 53c700 chip
                         Format: addr:<io>,irq:<irq>