Bug#354995: linux-2.6: The bug has been fixed upstream in 2.6.16
Followup-For: Bug #354995
As the subject states, the bug has been fixed upstream in 2.6.16-rc5.
I have tested this kernel myself and the clock _no longer_ runs too
fast without passing 'noapic' or 'no_timer_check' parameter to the kernel.
The relevant excerpt from the 2.6.16-rc5 changelog:
Author: Andi Kleen <firstname.lastname@example.org>
Date: Sun Feb 26 04:18:52 2006 +0100
[PATCH] x86_64: Better ATI timer fix
The previous experiment for using apicmaintimer on ATI systems didn't
work out very well. In particular laptops with C2/C3 support often
don't let it tick during idle, which makes it useless. There were also
some other bugs that made the apicmaintimer often not used at all.
I tried some other experiments - running timer over RTC and some other
things but they didn't really work well neither.
I rechecked the specs now and it turns out this simple change is
actually enough to avoid the double ticks on the ATI systems. We just
turn off IRQ 0 in the 8254 and only route it directly using the IO-APIC.
I tested it on a few ATI systems and it worked there. In fact it worked
on all chipsets (NVidia, Intel, AMD, ATI) I tried it on.
According to the ACPI spec routing should always work through the
IO-APIC so I think it's the correct thing to do anyways (and most of the
old gunk in check_timer should be thrown away for x86-64).
But for 2.6.16 it's best to do a fairly minimal change:
- Use the known to be working everywhere-but-ATI IRQ0 both over 8254
and IO-APIC setup everywhere
- Except on ATI disable IRQ0 in the 8254
- Remove the code to select apicmaintimer on ATI chipsets
- Add some boot options to allow to override this (just paranoia)
In 2.6.17 I hope to switch the default over to this for everybody.
Signed-off-by: Andi Kleen <email@example.com>
Signed-off-by: Linus Torvalds <firstname.lastname@example.org>
-- System Information:
Debian Release: testing/unstable
APT prefers unstable
APT policy: (500, 'unstable')
Architecture: amd64 (x86_64)
Shell: /bin/sh linked to /bin/bash
Kernel: Linux 2.6.15-1-amd64-k8
Locale: LANG=lt_LT, LC_CTYPE=lt_LT (charmap=ISO-8859-13)