[PATCH] i386: disable local apic timer via command line or dmi quirk

The local APIC timer stops to work in deeper C-States.  This is handled by
the ACPI code and a broadcast mechanism in the clockevents / tick managment
code.

Some systems do not expose the deeper C-States to the kernel, but switch
into deeper C-States behind the kernels back.  This delays the local apic
timer interrupts for ever and makes the systems unusable.

Add a command line option to disable the local apic timer and a dmi
quirk for known broken systems.

Andi sayeth:

  While not wrong by itself i think it is still better to use some heuristic
  -- like "has battery in ACPI" With the DMI table if the problem is more wide
  spread we will just continue extending it.

  But anyways should be ok now for .21 although I'm not really happy with
  it.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: john stultz <johnstul@us.ibm.com>
Grudgingly-acked-by: Andi Kleen <ak@suse.de>
Cc: Len Brown <lenb@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 856c8b114e71..06377c76e734 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1117,6 +1117,8 @@ and is between 256 and 4096 characters. It is defined in the file
 
         nolapic         [IA-32,APIC] Do not enable or use the local APIC.
 
+        nolapic_timer   [IA-32,APIC] Do not use the local APIC timer.
+
         noltlbs         [PPC] Do not use large page/tlb entries for kernel
                         lowmem mapping on PPC40x.