[fedora-virt] interesting kvm glitches

[Avi Kivity]

On 12/18/2009 03:08 AM, Tom Horsley wrote:
> I have been converting lots of old xen hvm images to run under
> kvm with a new fedora 12 replacing the old debian on the
> host machine, and I had a couple of examples of strange
> behavior I wonder if anyone else has seen:
>
> One machine booted just fine several times, then one boot
> the kernel paniced saying the apic wasn't working and I
> should boot with noapic. It has worked fine ever since then,
> but somehow it had a problem that once.
>    

It's most likely the timer calibration.  The kernel attempts to measure 
the timer rate, but on an overloaded machine it might miss all the timer 
interrupts due to the cpu being used for other guests.  Newer guest 
kernels have a workaround for that.


> Another machine apparently boots OK, but /proc/cpuinfo reports
> the cpu speed as 0 HZ - quite an accomplishment (which I
> noticed because some test programs were trying to do some
> time base calculations and they all divided by zero :-).
> I haven't yet booted this machine again to see if it
> does this every time or not.
>    

This is strange.  Please see if it reproduces and describe the guest.

> Of course, I also have a handful of machine that simply
> refuse to boot all the way up (mostly various opensuse versions).
> I may have to try reinstalling them and see if they work
> better when under kvm at creation time.
>    

Where do they stop?

Might be incompatible drivers.

-- 
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