Re: [Qemu-devel] [PATCH 08/11] QMP: Asynchronous messages enable/disable support

[Anthony Liguori]

On 01/22/2010 02:09 PM, Luiz Capitulino wrote:
> On Fri, 22 Jan 2010 12:05:19 -0600
> Anthony Liguori<address@hidden>  wrote:
>
>    
> > On 01/21/2010 03:09 PM, Luiz Capitulino wrote:
> >      
> > > This commit disables asynchronous messages by default and
> > > introduces two new QMP commands: async_msg_enable and
> > > async_msg_disable.
> > >
> > > Each QMP Monitor has its own set of asynchronous messages,
> > > so for example, if QEMU is run with two QMP Monitors async
> > > messages setup in one of them doesn't affect the other.
> > >
> > > To implement this design a bitmap is introduced to the
> > > Monitor struct, each async message is represented by one bit.
> > >
> > > Signed-off-by: Luiz Capitulino<address@hidden>
> > >
> > >        
> > Ah, I see I was a little confused.
> >
> > I'd suggest making async message masking an independent mechanism.
> > Capabilities should strictly deal with protocol changes, not feature
> > details.
> >      
>   To summarize (after a IRC talk): async messages are considered a
> capability and should be enabled during the negotiation phase but
> the masking of particular messages are not and can be done at
> any time after the negotiation phase.
>    

Just to further clarify, the mental model I have of capabilities is that 
they are things that affect the protocol itself.  Additional features 
(new command options, new commands, new async messages) are things that 
are enabled/discovered in a different way.

Async messages themselves are a capability since it changes the 
protocol.  Timestamps would be another capability and a new data type 
(like an uint64 type) would be a new capability.

>   I'm ok with that, Markus?
>    

Regards,

Anthony Liguori