Re: [Qemu-devel] [PATCH] Migration compatibility for serial

["Michael S. Tsirkin" <mst@redhat.com>]

On Wed, Jun 17, 2015 at 01:44:12PM +0200, Paolo Bonzini wrote:
> 
> 
> On 17/06/2015 13:40, Dr. David Alan Gilbert wrote:
> > > Like Juan, I see where you're coming from.  But it's a slippery slope,
> > > and upstream chose not to go down it.
> > 
> > Whatever choice upstream may have made, that was a long time ago
> > and doesn't mean it can't change.
> 
> My question really is: what has changed for this choice to not make
> sense anymore?

We are getting more testing for migration is what changed.  And ping
pong migration - which requires backward migration - is very useful for
such testing.

> Backward migration is not supported upstream except between minor
> releases.  It is really the same as in RHEL, except that a minor release
> lasts a few years less. :)
> 
> Paolo

Not supported does not mean we can't add code to make it work if it's
helpful for developers.  All this assuming this is not too much code,
and not too ugly.

-- 
MST