Re: [REGRESSION from 2.6.23-rc8] (was: Re: 2.6.23-rc4-mm1 and -rc6-mm1: boot failure on HP nx6325, related to clockevents)

From: Andi Kleen
Date: Sun Sep 30 2007 - 05:58:33 EST

> > OK, this explains 2) and 3). I just looked into the code and the logic
> > vs. noapictimer on SMP is completely broken.

noapictimer really doesn't make any sense on non SMP imho with the old
timer architecture. That is why I never bothered to implement it.
It's purely a UP hack.

> ..and thanks for the explanation.
> Thanks for finding it so quickly guys. Sounds like this will be fixed
> properly in 2.6.24 with the x86 merge (which hopefully brings in the hrt
> patch too)

There is nothing really to fix currently. Clockevents changes behaviour
majorly (always using APIC timers without irq 0 backups[1]) and that causes
problems that need new workarounds and new fixes (surprise surprise!)

That merge would probably fix a few more such "Thomas doesn't understand
the code" bugs I guess because he hacks much more on i386 than x86-64;
but if the overall result will be really better is a totally different


[1] Or let's call it "I trust all my time to the CPU" and no more southrbridge
aka put all eggs in one basket. Given the trends in CPU power saving that
is a quite dangerous strategy.
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