Re: [Qemu-devel] Re: [PATCH 03/26] Remove SaveVM v2 support

[Anthony Liguori]

Stefano Stabellini wrote:
> First of all sorry if I come late into the discussion but I was on
> vacation.
>
> We just need the loading function and we don't even need the ram loading
> portion of it but just the device state loading. Of course for qemu
> doesn't make sense to keep only the device loading function around
> therefore I suggested to keep it all and fix it instead.
>
> As I have mentioned before I think it is really important to provide
> backward compatibility, and we do in xen and xenserver without too much
> trouble.
> I am willing to send patches to fix the device state loading functions,
> and we might already have few fixes in qemu-xen.
>
> I realize that my use case is off the tree so you have all the rights
> not to be interested in it, nonetheless I hope you don't completely
> discard it because it would make our life difficult.
>   

Practically speaking, we only have the ability to support back to 
0.10.0.  We simply didn't have the necessary infrastructure in place to 
support anything older than that.
v3 of the savevm protocol came before 0.10.0 so there's no need for us 
to every support v2 or v1 of the protocol.

There are some major changes happen to the savevm infrastructure for 
0.12.0.  I'd suggest that instead of not removing v2, we remove it, 
finish up the changes, then you can look at re-adding support for it.

Some of the features of v2 may be difficult to carry forward (like the 
savevm section sizes).

And FWIW, I don't necessarily think we'll see a v4 for 0.12.0.  I'm not 
convinced it's needed and/or useful.

Regards,

Anthony Liguori