Re: Domain Save Image Format proposal (draft B)

[David Vrabel <david.vrabel@citrix.com>]

On 11/02/14 16:49, Ian Jackson wrote:
> David Vrabel writes ("Domain Save Image Format proposal (draft B)"):
>> Here is a draft of a proposal for a new domain save image format.  It
>> does not currently cover all use cases (e.g., images for HVM guest are
>> not considered).
> 
> I think this is a good start.  I've made some other comments already.
> 
>> Overview
>> ========
> 
> I would like to make another perhaps controversial suggestion.  We
> should explicitly specify that the receiver may advertise its
> capabilities to the sender, so that backwards-migration _can_ be
> supported if we choose to do so.
> 
> In practice I think that means a capability advertisement block.
> Probably, one bit per version, one bit per record type, etc.
> 
> I greatly prefer doing forward-compatibility with new record type
> enums etc. than with version numbers.  Version numbers presuppose a
> strict global order on all the implementations' capabilities, which is
> of course not necessarily true in free software.

I think I quite like this idea.  There would still need to be a central
repository of record types.

David