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[Xen-devel] RE: Genapic testing


The enable_apic_mode() function no longer does anything useful on our
current systems. They are present in the 2.6 LK to support an older
class of Unisys machines. I am not trying to run Xen on those systems.

I tried using Don's patch. The "time went backwards" message no longer
shows up. But the system is losing interrupts now. I have attached the
boot output. It looks like there could be something amiss in the IO APIC
redirection table setup. I am presently looking into that.


> -----Original Message-----
> From: Keir Fraser [mailto:Keir.Fraser@xxxxxxxxxxxx]
> Sent: Tuesday, May 31, 2005 2:24 PM
> To: Puthiyaparambil, Aravindh
> Cc: Davis, Jason; xen-devel@xxxxxxxxxxxxxxxxxxx; Vessey, Bruce A;
> Subrahmanian, Raj
> Subject: Re: Genapic testing
> On 26 May 2005, at 21:52, Puthiyaparambil, Aravindh wrote:
> >> Are the TSCs on all CPUs suitably sync'ed up? If the PIT is firing
> >> we are updating our timestamp info often enough, and all CPUs have
> >> similar TSC values, then all should work okay. Don Fry has a patch
> > that
> >> handles unsync'ed TSCs, if that turns out to be the problem.
> >
> > On native Linux the skew is reported and is "fixed up". But that
> > not mean the TSC was really adjusted, it will keep running with this
> > gap. So the CPU TSC skew could be the problem. The only difference
> > that for Xen, the skew for the boot CPU is unusually high.
> Aravindh,
> I noticed yesterday that I was missing a call to enable_apic_mode()
> during local APIC initialisation. On es7000 this does some cryptic
> twiddling that I don't understand, but I suppose could arbitrarily
> break something important. :-)
> I've now fixed this omission so it is probably worth trying to boot on
> es7000 and see if the timer problems have disappeared.
>   -- Keir

Attachment: xen3-percpu-es7000.txt
Description: xen3-percpu-es7000.txt

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