[Qemu-devel] Re: KVM call agenda for Apr 27

[Kevin Wolf]

Am 27.04.2010 11:32, schrieb Dor Laor:
> On 04/27/2010 12:22 PM, Avi Kivity wrote:
>> On 04/27/2010 12:08 PM, Dor Laor wrote:
>>> On 04/27/2010 11:56 AM, Avi Kivity wrote:
>>>> On 04/27/2010 11:48 AM, Dor Laor wrote:
>>>>> IMHO the whole thing is way over engineered:
>>>>> a) Having another channel into qemu is complicating management
>>>>> software. Isn't the monitor should be the channel? Otherwise we'll
>>>>> need to create another QMP (or nbd like Avi suggest) for these
>>>>> actions. It's extra work for mgmt and they will have hard time to
>>>>> understand events interleaving of the various channels
>>>>
>>>> block layer plugins allow intercepting all interesting block layer
>>>> events, not just write-past-a-watermark, and allow actions based on
>>>> those events. It's a more general solution.
>>>
>>> No problem there, as long as we do try to use the single existing QMP
>>> with the plugins. Otherwise we'll create QMP2 for the block events in
>>> a year from now.
>>
>> I don't see how we can interleave messages from the plugin into the qmp
>> stream without causing confusion.
> 
> Those are QMP async events.
> 
> Since Kevin suggested adding even more events (was is cynical?) 

The part about adding a scripting engine was.

The idea of adding a generic event (one event, not even more!) for a QMP
query-* result change doesn't sound that bad on second thought, though.
It's not specific for watermarks and looks less complicated than all the
plugin, NBD and QMP2 stuff.

It's almost the same as Anthony's polling suggestion (works with query-*
results from user perspective), just without polling.

Kevin