Re: [Qemu-devel] [PATCH 3/4] virtio: modify savevm to have a stable wire format

[Paolo Bonzini]

Il 14/12/2012 01:57, Rusty Russell ha scritto:
> With the new code we only need the head from that structure.

We also need to do again all validation of the elements if we fetch it
back from the data.  Sometimes the parsed data is saved elsewhere (e.g.
in a SCSIRequest struct that is serialized by the SCSI subsystem) and
that data may be inconsistent with whatever you read from guest memory.
 It's a can of worms.

>> I'm certainly in favor of cleaning up the savevm format and probably
>> leaving the existing load/save functions as-is for legacy purposes.
>> I'll leave that as an exercise for someone else though :-)
> 
> What is the rule about new versions?  Can we introduce a new save
> version at any time, or only at major qemu version changes?

Any time, but we provide a backwards-compatible loader for older versions.

Paolo