Re: [Qemu-devel] [PATCH v4] XBZRLE delta for live migration of large memory apps

[Anthony Liguori]

On 08/10/2011 11:08 AM, Avi Kivity wrote:
> On 08/10/2011 06:58 PM, Anthony Liguori wrote:
> > > I don't think we should couple the two features together.
> >
> >
> > ASN.1 is orthogonal to capabilities.
> >
> > Capabilities are a hard requirement before merging any new type of
> > compression algorithm IMO.
>
> Right now we have capabilties in the form of -help output.
>
> If -help says
>
> -no-xzbrle disable xzbrle support
>
> (or -migration-compression xzbrle=off, or something) that's sufficient
> for management tools.

This is static, not dynamic.  You may attempt to migrate to another host 
that supports it and then migrate to a second host that doesn't support 
it after the first migration fails.

> We shouldn't block this feature just because some monitor facility is
> not yet implemented.

We shouldn't make *any* changes to the migration protocol before we have 
a feature negotiation capability.  I only want to do a hard break of the 
protocol once.

Regards,

Anthony Liguori