Re: [1/6] 2.6.21-rc4: known regressions

Thomas Gleixner
2007-03-23T11:48:50Z

On Fri, 2007-03-23 at 12:42 +0100, Ingo Molnar wrote:
> there's a new post-rc4 regression: my T60 hangs during early bootup. I
> bisected the hang down to this recent commit:
>
> | commit 25496caec111481161e7f06bbfa12a533c43cc6f
> | Author: Thomas Renninger <trenn@suse.de>
> | Date: Tue Feb 27 12:13:00 2007 -0500
> |
> | ACPI: Only use IPI on known broken machines (AMD, Dothan/BaniasPentium M)
>
> undoing this change fixes my T60 so it correctly boots again.
>
> the commit has this confidence-raising comment:
>
> | However, I am not sure about the naming of the parameter and how it
> | could/should get integrated into the dyntick part
> | (CONFIG_GENERIC_CLOCKEVENTS). There, a more fine grained check (TSC
> | still running?, ..) is needed?
>
> could we please revert this commit until it's done correctly?
>
> and did this end up being a 'fix'? The change weakens the scope of a
> hardware workaround, which IMO has no place so late in the cycle. At a
> minimum the clockevents maintainer (Thomas) should have been Cc:-ed on
> it.

Ingo,

I had seen it before, and I had no objections under the premise, that it
does not break things and especially survives on Andrews VAIO. I
expected that to come in via -mm so it gets enough testing.

We should revert that patch and add a "trust_lapic_timer_in_c2"
commandline option instead. So we are on the safe side.

tglx