On 08/12/2011 05:16 PM, Anthony Liguori wrote:
Because of the change we made for 0.15, this is no longer strictly needed. It only matters if we add a subsection to a structure, right?
Yes. We can also check the current migration format in the "needed" function for such subsections, if necessary. This is what I plan to do for the floppy subsection, skipping it for old machine types that do not use the new migration format.
I'm definitely not saying we shouldn't do this BTW. But trying to understand whether we can position this as a strictly optional feature (iow, a capability) or whether this requires a hard break in the migration protocol.
This what? :) Adding a subsection to a structure, or using the new migration format? If you mean using the new format only when you have subsections in a structure, then you'll need quite a bit of new code to try all VMState handlers and see if they'll need a subsection. I don't think it's worth it, also because we all hope this is a temporary solution until we have a serious format (e.g. ASN-1).
Paolo
