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Re: [Xen-devel] [PATCH 2/2] x86/hvm: fix corrupt ACPI PM-Timer during live migration

On 05/15/2013 11:54 PM, Jan Beulich wrote:
On 15.05.13 at 16:49, Alex Bligh <alex@xxxxxxxxxxx> wrote:
--On 15 May 2013 15:31:19 +0100 Jan Beulich <JBeulich@xxxxxxxx> wrote:

Did this ever get committed? I can't immediately find a commit.

No, it didn't - no-one knowing that code well enough ever acked
patch 1, and without that we can't apply the patch here.

I certainly am not someone who knows that code well, so can't help
with that. But I (or more accurately Diana) can reliably replicate
live migrate on HVM and qemu-upstream DM causing (a) ACPI entries
to disappear from xenstore and (b) walltime to fail to advance in
the migrated domain until the walltime is manually set (stuck

Is this likely to be related?

I'd like to defer to Kouya to tell whether that matches the
symptoms he saw.

I don't think my fix is related to Alex's problem.
I observed that gettimeofday() sometimes goes backward *a few seconds*
on migration.

In linux OSs, ACPI Timer value is masked by 24bit.
The valid range:
     (1 / 3.579545MHz) * 0xffffff = 4.7sec
So, the effect of the corrupt ACPI timer is at most 4.7 sec.
The clock shouldn't be frozen for a long time.

Apparently (a) sounds like a problem of xl toolstack.


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