Re: [libvirt] Re: [Qemu-devel] [PATCH 1/6] Allow multiple monitor devices (v2)

[Avi Kivity <avi@redhat.com>]

Jan Kiszka wrote:
>> I'm not sure I understand your questions.  Multiple monitor sessions are
>> like multiple shell sessions.  I don't think a control program should
>> use more than one session, but it should allow a developer to connect to
>> issue 'info registers' and 'x/20i' commands.  Of course if a developer
>> issues 'quit' or a hotunplug command, things will break.
>>     
>
> We agree if we want decoupled states of the monitor sessions (one
> session should definitely not be used to configure the output of another
> one). But I see no issues with collecting the events in one session that
> happen to be caused by activity in some other session. But maybe I'm
> missing your point.
>   

The management application will still think the device is plugged in, 
and things will break if it isn't.

Of course if you asked for notification X on session Y, then event X 
should be delivered to session Y no matter how it originated (but not to 
session Z).

>   
>>> Please no more async notifications to the monitors. They are just ugly
>>> to parse, at least for us humans. I don't want to see any notification
>>> in the middle of my half-typed command e.g.
>>>   
>>>       
>> If we can identify an interactive session, we might redraw the partial
>> command after the prompt.
>>     
>
> Uhh, please not this kind of terminal reprinting. The terminal user keep
> full control over when things can be printed.
>   

Very well.  I guess a human user can open another session for 
notifications, if they are so inclined.

>   
>> btw, why would a human enable notifications?  Note notifications enabled
>> on the management session will only be displayed there.
>>     
>
> It's true that the common use case for events will be monitor
> applications. Still, enabling them for testing or simple scripting
> should not switch on ugly output mode or complicate the parsing.
>   

Fair enough.

-- 
Do not meddle in the internals of kernels, for they are subtle and quick to panic.