From mboxrd@z Thu Jan  1 00:00:00 1970
From: George Dunlap <george.dunlap@eu.citrix.com>
Subject: Re: HVM Migration of domU on Qemu-upstream DM causes
 stuck system clock with ACPI
Date: Mon, 3 Jun 2013 18:12:47 +0100
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To: Alex Bligh <alex@alex.org.uk>
Cc: Ian Campbell <Ian.Campbell@citrix.com>, Stefano Stabellini <stefano.stabellini@eu.citrix.com>, Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>, xen-devel@lists.xen.org, David Vrabel <david.vrabel@citrix.com>, Anthony PERARD <anthony.perard@citrix.com>, Diana Crisan <dcrisan@flexiant.com>, =?ISO-8859-1?Q?Roger_Pau_Monn=E9?= <roger.pau@citrix.com>
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On 03/06/13 18:09, Alex Bligh wrote:
> George,
>
> --On 3 June 2013 12:16:45 +0100 George Dunlap 
> <george.dunlap@eu.citrix.com> wrote:
>
>> Right -- it seems to be working for me too.  I'm on migrate #52, and
>> there hasn't been a single warning from Linux's clock code about
>> increasing min_delay.
>>
>> Diana / Alex: It looks like we might have a work-around for you. Diana,
>> would it be possible for you to do the following:
>>   1. Add tsc_mode="native_paravirt" to your config file
>>   2. Try it again localhost migrate to see if you run into any problems
>>   3. Try it again migrating between machines, just to make sure we've
>> solved the important problem
>
> Thanks for this.
>
> Will this work with all guests? We (unfortunately) do not know whether 
> the
> guest is Linux with or without PV, Windows with or without PV or what. I
> /think/ this is going to give problems when the guest is not using
> the PV timer (including Windows). Is that right?
>
> I'd be happiest if it selected native_paravirt whenever the guest was
> using the PV timer, but not otherwise. Happy to test patches for that.

I'm not sure the effect, but I suspect it probably won't work quite 
right.  Might be worth a quick test.

We do want to fix this properly (which means, "just works w/o having to 
use a work-around"); I'm trying to understand the exact nature of the 
error now.

  -George