Re: HVM Migration of domU on Qemu-upstream DM causes stuck system clock with ACPI

[George Dunlap <george.dunlap@eu.citrix.com>]

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