Re: [BUG] APM resume breakage from 2.6.18-rc1 clocksource changes

[Valdis.Kletnieks@vt.edu]

On Sun, 09 Jul 2006 22:58:31 +0200, Mikael Pettersson said:

> I've traced the cause of this problem to the i386 time-keeping
> changes in kernel 2.6.17-git11. What happens is that:
> - The kernel autoselects TSC as my clocksource, which is
>   reasonable since it's a PentiumII. 2.6.17 also chose the TSC.
> - Immediately after APM resumes (arch/i386/kernel/apm.c line
>   1231 in 2.6.18-rc1) there is an interrupt from the PIT,
>   which takes us to kernel/timer.c:update_wall_time().
> - update_wall_time() does a clocksource_read() and computes
>   the offset from the previous read. However, the TSC was
>   reset by HW or BIOS during the APM suspend/resume cycle and
>   is now smaller than it was at the prevous read. On my machine,
>   the offset is 0xffffffd598e0a566 at this point, which appears
>   to throw update_wall_time() into a very very long loop.

Does applying this patch make it work?

ftp://ftp.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.18-rc1/2.6.18-rc1-mm1/broken-out/adjust-clock-for-lost-ticks.patch

Or is this a different breakage?

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