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

[Avi Kivity <avi@redhat.com>]

On 01/22/2010 08:05 PM, Anthony Liguori 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<lcapitulino@redhat.com>
>
> 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.
>
> For instance, protocol timestamps are something would reasonable 
> considered a capability.  Extended data types would be a capability.
>
> Another way to look at it, is that if you're writing a client library, 
> the capability negotiation should be entirely invisible to the end API 
> user.
>

I agree with that, but we can look at async messages as a baseline 
protocol capability (thus no negotiation required), and the new command 
only enabled individual messages.

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