[libvirt] [Qemu-devel] Re: [patch 2/3] Add support for live block copy

[Dor Laor]

On 02/27/2011 07:25 PM, Anthony Liguori wrote:
> On 02/27/2011 10:02 AM, Dor Laor wrote:
>> On 02/27/2011 03:49 PM, Anthony Liguori wrote:
>>> On 02/27/2011 03:55 AM, Dor Laor wrote:
>>>> What about a simpler approach were QMP events will be written to a
>>>> event-log-file (or even named pipe).
>>>
>>> The management tool can just use a small daemon that does nothing other
>>> than write QMP events to a log. There's no real need for this code to
>>> live in QEMU.
>>>
>>
>> IIUC in case the management daemon will run qemu using named pipe for
>> qmp it will happen automatically.
>
> No, the event model is changing (it was always intended to change
> though). Events will need explicit registration so it's necessary to
> have bidirectional communication.

But the mgmt->qemu direction is only about event registration, it's not 
valuable info.
It's a simpler approach than relaying on another config file and it is 
safer than having a separate mgmt daemon to log these events.
Cross posting to libvirt-list to hear their view.

>
> So you can't just do -qmp foo -chardev file:event.log,id=foo. You won't
> actually see most of the events.
>
> Regards,
>
> Anthony Liguori
>
>> If you agree to this approach it will simplify the more complex config
>> file option (although it is nice to have as independent option for
>> single hosts managed by simpler mgmts)
>>
>>> Since events are posted, even if we wrote it in QEMU, the event wouldn't
>>> be guaranteed on disk by the time the event invocation returns.
>>>
>>> Regards,
>>>
>>> Anthony Liguori
>>>
>>
>>
>
>