Re: 2.6.13-rc3-mm3

From: Martin J. Bligh
Date: Fri Jul 29 2005 - 10:26:17 EST

>> > - There's a pretty large x86_64 update here which naughty maintainer wants
>> > in 2.6.13. Extra testing, please.
>> Is still regressed as of 2.6.12 for me, at least. Crashes in TSC sync.
>> Talked to Andi about it at OLS, but then drank too much to remember the
>> conclusion ... however, it's still broken ;-)
>> Matrix is here (see left hand column).
>> Example boot log is here:
> Does Eric's recent fix fix it?
> From: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>
> sync_tsc was using smp_call_function to ask the boot processor to report
> it's tsc value. smp_call_function performs an IPI_send_allbutself which is
> a broadcast ipi. There is a window during processor startup during which
> the target cpu has started and before it has initialized it's interrupt
> vectors so it can properly process an interrupt. Receveing an interrupt
> during that window will triple fault the cpu and do other nasty things.

Wheeeeeeee! that does indeed seem to work. Nice job.

> I believe this patch suffers from apicid versus logical cpu number
> confusion. I copied the basic logic from smp_send_reschedule and I can't
> find where that translates from the logical cpuid to apicid. So it isn't
> quite correct yet. It should be close enough that it shouldn't be too hard
> to finish it up.
> More bug fixes after I have slept but I figured I needed to get this
> one out for review.

Eric, when you have a final version, throw it over to me, and I'll give
that one a spin-test too ...


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