Re: Question re live migrate on Xen 4.2 re different cpu capabilities

[Olaf Hering <olaf@aepfle.de>]

On Thu, Feb 07, Alex Bligh wrote:

> >You can also level down an entire host using the cpuid_mask_* command
> >line options described in
> >http://xenbits.xen.org/docs/unstable/misc/xen-command-line.html
> 
> Thanks - that's really helpful. Looking at the documentation for cpuid=
> I can't see an obvious way of saying 'mask everything except the
> least common denominator of features' using the libxl method, without
> having prior knowledge of what each version of xen supports. I'm not
> even clear how to do this on the xend method (obviously I want to
> pass long bitstrings of zeros, but how many?). Am I missing something?

cpuid= is what the guest sees, so its not so much a feature of Xen
itself but what the host cpu provides. I'm not sure if Xen can emulate
certain important bits. The wikipedia CPUID entry has a list what each
bit means.

Olaf