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: Thomas Gleixner
Date: Wed Sep 26 2007 - 18:35:23 EST

On Wed, 2007-09-26 at 15:22 -0700, Linus Torvalds wrote:
> On Wed, 26 Sep 2007, Thomas Gleixner wrote:
> > >
> > > 1) current Linus' tree doesn't boot with any command line (regression)
> > >
> > > [ Linus, please revert commit e66485d747505e9d960b864fc6c37f8b2afafaf0
> Reverted.
> > OK, this explains 2) and 3). I just looked into the code and the logic
> > vs. noapictimer on SMP is completely broken.
> ..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)

It's even worse than I thought on the first check:

"noapictimer" on the command line of an SMP box prevents _ONLY_ the boot
CPU apic timer from being used. But the secondary CPU is still
unconditionally setting up the APIC timer and uses the non calibrated
variable calibration_result, which is of course 0, to setup the APIC
timer. Wreckage guaranteed.


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