I am a graduation student at the University of West-Flanders in Belgium and I am researching the possibilities of XenMotion in Citrix XenServer. Now I am trying to get XenMotion working from an Intel Xeon X5365 (Clovertown 3GHz) to an Intel Xeon X5470 (Harpertown 3.33 GHz).

I am guessing that maybe the SSE4.1 capability of the Harpertown is what's causing the failure. (It won't be the clockspeed because migrating from X5365 to E5345 (Clovertown 2.33 GHz) works perfectly)

My collegue is working on ESX, trying out VMotion, and he has the capability of masking cpu flags from withing ESX.

Now I am wondering if it would be possible to hide flags in the proc filesystem or with an instruction at boottime maybe?

1 Answer 1


The bad news is: there isn't presently any support for this in XenServer 5.5 today.

The good news is: it is a feature of the underlying XenSource hypervisor, so you can probably expect to see it in XenServer in the near future.

  • That's too bad. Do you have a official source on this?
    – Hofa
    Jun 4, 2009 at 8:52
  • There isn't much official detail which is public facing. Confirmation that it doesn't exist in XenServer 5.5 is here - bit.ly/IYPgK. It was introduced to Xen HV 3.3 under the name "CPUID Feature Levelling". You could check the BIOS of the machine with the newer CPU to see if it's possible to disable any extra featuresets, which would make the CPUs more alike, but it may be unlikely.
    – Dan Carley
    Jun 4, 2009 at 9:23

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