Re: [Qemu-devel] [PATCH 0/8]: QMP feature negotiation support

[Anthony Liguori <anthony@codemonkey.ws>]

On 02/01/2010 01:50 PM, Luiz Capitulino wrote:
>> Capability selection could be done as an object where the name/value
>> pairs are capability/argument.  If you need multiple arguments for a
>> capability, make the capability's value an object.
>>      
>   That's exactly what seems complicated to me, because besides performing
> two functions (enable/configure) some feature setup could require
> more commands to be done in a clear way.
>    

I think the way to do this would be:

server -> client: version & capabilities offer (including cap 
NEGOTIATE_FEATURES)
client -> server: capability selection (including cap NEGOTIATE_FEATURES)
server -> client: okay or error
(session is now in negotiation mode)
client -> server: configure features
server -> client: ack/nack
client -> server: change to command mode
server -> client: ack/nack

So Markus' proposal solves our immediate needs while making it possible 
to implement something more sophisticated IFF we end up needing it for 
some reason.  It's a little more chatty than Luiz's proposal but since 
there isn't an obvious need now, I think it's a reasonable trade off to 
make.

Regards,

Anthony Liguori