Re: [Xen-devel] xen live migration falied

[Olaf Hering <olaf@xxxxxxxxx>]

On Wed, Jun 06, elahe shekuhi wrote:

> (One machine has core i7 processor while another is core 2 quad system).
> 
> 
> ÂI have searched the net and this list and found a few posts mentioning this
> error, but no solution, not even a hint
> Â Âon the source of the problem.

As mentioned by others, for migration (or save/restore) either both
systems have to have identical cpus or the guests view of the cpu has to
be adjusted with the cpuid= config option in the vm config file. In
other words, the "least common denominator" of cpu features has to be
configured.

See my recent post which tries to explain the cpuid= config option:

http://lists.xen.org/archives/html/xen-devel/2012-06/msg00303.html

There is an example in there for xend, and also a link to wikipedia
which has a good list of cpu features. I suggest to boot both systems
with a native kernel and compare the cpu features. Perhaps with
something like this:

grep -wm1 ^flags /proc/cpuinfo | xargs -n1 | sort > /share_dir/core2.txt
grep -wm1 ^flags /proc/cpuinfo | xargs -n1 | sort > /share_dir/i7.txt
diff -u /share_dir/core2.txt /share_dir/i7.txt

I think most of the lines starting with '+' are features which exist
only in i7, which can be hidden with the cpuid= option.


Make sure to install the xen packages from the 12.1 update repository
since they contain two fixes for your environment: an xsave related bug
was fixed, and also guests with a cpuid= option were not restored at all
during system startup.


Olaf

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