Re: [kvm-devel] [BUG] Oops with KVM-27

From: Luca
Date: Mon Jun 11 2007 - 17:06:34 EST

On 6/11/07, Avi Kivity <avi@xxxxxxxxxxxx> wrote:
Luca wrote:
>> I've managed to reproduce this on kvm-21 (it takes many boots for this
>> to happen, but it does eventually).
> Hum, any clue on the cause?

From what I've seen, it's the new Linux clocksource code.

Actually I tried forcing the PIT (and any other combination of
tsc,acpi_pm,jiffies) as the clocksource, without success.

> Should I test older versions?

They're unlikely to be better. Instead, it would be best to see what
the guest is doing.

I suggest downloading the source rpm for the kernel, building it, and
sprinkling printk()s until we know exactly what source the guest is
executing at the time of the hang.

Ok, will do. Meanwhile I discovered that the kernel on the boot cd
(the one that hangs) is compiled for i586, while the one installed on
disk is for i686 (this one works).

i686 has this options enabled:


but disabling tsc on the command line doesn't make any difference. Is
it possible that KVM is choking on some instruction not used by the
i686 kernel?

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