RE: [Xen-users] Live Migration with different hardware

["Petersson, Mats" <Mats.Petersson@xxxxxxx>]

> -----Original Message-----
> From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx 
> [mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of 
> Dominik Klein
> Sent: 29 June 2007 13:24
> To: xen-users@xxxxxxxxxxxxxxxxxxx
> Subject: Re: [Xen-users] Live Migration with different hardware
> 
> > Will migration work from a P4 to a Xeon (Core2 
> Mircoarchitecure) ? Will 
> > migration work if they got different NIC? What are the limitations?
> 
> Afaik, you need identical CPU flags.
> 
> Compare the output of this command on your machines:
> cat /proc/cpuinfo|grep flags

That may well be the case. The "correct" test should really be something
like:

flags_new_cpu & ~flags_old_cpu != 0

That means, no flags on the old cpu that doesn't exist on the new CPU. 

I'm not sure how much, if any, flags are actually tested on the
migration path.

The good thing is that if the migration fails due to incompatible CPU's
(by testing flags) it should not "fail" the domain - that is, the domain
should stay on the original machine and you should get an error message
- at least that's how I understand it. 

> 
> A different NIC should not be a problem. Of course you might 
> want both 
> to be of the same speed. As long as you bridge them correctly, a 
> different NIC should not be an issue.

Yes, as long as you don't use "pci-passtrhough" to make a PCI card (e.g.
network card) available directly to the domain, the guest DOESN'T KNOW
what the REAL network card is [this makes the domain a driver domain,
and driver domains aren't allowed to be migrated anyways - that would be
TERRIBLY hard to implement, as there's no real good way to transfer the
internal state of the hardware owned on one domain to the next one]. 

--
Mats
> 
> Regards
> Dominik
> 
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