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

[Thomas Gleixner]

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@xxxxxxx>
> | 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


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