Re: [Qemu-devel] [RFC PATCH 0/4] Fix subsection ambiguity in the migration format

["Daniel P. Berrange" <berrange@redhat.com>]

On Mon, Jul 25, 2011 at 06:23:17PM -0500, Anthony Liguori wrote:
> We also need a way to future proof ourselves.
> 
> == What we can do ==
> 
> 1) Add migration capabilities to future proof ourselves.  I think
> the simplest way this would work is to have a
> 'query-migration-capabilities' command that returned a bitmask of
> supported migration features.  I think we also introduce a
> 'set-migration-capabilities' command that can mask some of the
> supported features.
> 
> A management tool would query-migration features on the source and
> destination, take the intersection of the two masks, and set that
> mask on both the source and destination.
> 
> Lack of support for these commands indicates a mask of zero which is
> the protocol we offer today.

This sounds like a very good idea to me.

> 5) .... We could support 50 formats if we wanted to.  As long as the
> transport is distinct from the serialization and compat routines, it
> really doesn't matter.

Lets not get too carried away :-) Even just dealing with the different
ways libvirt can invoke & manage the migration process gives me ~100
test scenarios to run through for each release of libvirt. The fewer
QEMU testing combinations we need to worry about the better, because
it quickly explodes with migration as you throw different versions
into the mix.


Daniel
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