Re: [Qemu-devel] [PATCH v4 20/47] Add migration-capability boolean for postcopy-ram.

[Dr. David Alan Gilbert]

* Eric Blake (address@hidden) wrote:
> On 10/03/2014 11:47 AM, Dr. David Alan Gilbert (git) wrote:
> > From: "Dr. David Alan Gilbert" <address@hidden>
> > 
> > Signed-off-by: Dr. David Alan Gilbert <address@hidden>
> > Reviewed-by: Eric Blake <address@hidden>
> > ---
> >  include/migration/migration.h | 1 +
> >  migration.c                   | 9 +++++++++
> >  qapi-schema.json              | 6 +++++-
> >  3 files changed, 15 insertions(+), 1 deletion(-)
> > 
> 
> >  #
> > +# @x-postcopy-ram: Start executing on the migration target before all of 
> > RAM has been
> > +#          migrated, pulling the remaining pages along as needed. NOTE: If 
> > the
> > +#          migration fails during postcopy the VM will fail.  (since 2.2)
> > +#
> >  # Since: 1.2
> >  ##
> >  { 'enum': 'MigrationCapability',
> > -  'data': ['xbzrle', 'rdma-pin-all', 'auto-converge', 'zero-blocks'] }
> > +  'data': ['xbzrle', 'rdma-pin-all', 'auto-converge', 'zero-blocks', 
> > 'x-postcopy-ram'] }
> 
> Can we wrap this to keep things in 80 columns?

Done.

> Also, the question was
> raised on the libvirt list on whether the interface is stable enough to
> name this 'postcopy-ram' from the get-go (rather than marking the
> interface experimental), so that libvirt can start using it sooner.

I'm still nervous about that, what I intend to do is add one
patch at the end of the series that removes the x-  so that can
get discussed separately.

While I'm confident that the interface to libvirt is stable, removing the x-
declares that the whole thing is stable and I then have to maintain
migration compatibility; and it seemed sensible to let people try it for 
a release; however if libvirt have no way to support QEMUs ability to have
experimental features, I guess no one is actually going to try it, which is
very disappointing.

Dave

> -- 
> Eric Blake   eblake redhat com    +1-919-301-3266
> Libvirt virtualization library http://libvirt.org
> 


--
Dr. David Alan Gilbert / address@hidden / Manchester, UK