Re: [Qemu-devel] [PATCH] migration: remove subsections in fdc and rtl8139 and bump versions

[Paolo Bonzini <pbonzini@redhat.com>]

On 08/04/2011 02:59 PM, Kevin Wolf wrote:
>> >
>> >  I have.  If we are changing a protocol in an incompatible version, we
>> >  can remove a lot of warts that current descriptions have.  Not that
>> >  Paolo protocol is bad, but if we are going to do some change, adding
>> >  things like size, removing previous warts, etc is the way to go.
> So how about stating clearly that migrating between 0.x and 1.x won't
> work and using the next few months to develop a sane migration protocol?

I think that's too early to state, perhaps we can keep backwards 
compatibility---who knows.

And in case we totally screw up in 1.x, we still have my tweaked format 
as a backup.

> We'll still have to do something about 0.15 and it's not very nice to
> break migration twice, but seems there is no way around it.

There is!  Migration didn't break _that_ much with subsections, exactly 
because the buggy case occurs when subsections are sent and subsections 
are rare.  If we always send them, as we did in practice with the 
floppy, we break stuff.  That's why for 0.15 reverting the floppy fix is 
the simplest course of action.

Paolo