Re: [Qemu-devel] chardev's and fd's in monitors

[Paolo Bonzini <pbonzini@redhat.com>]

On 21/10/2016 11:12, Markus Armbruster wrote:
> Paolo Bonzini <pbonzini@redhat.com> writes:
> 
>> On 20/10/2016 10:37, Daniel P. Berrange wrote:
>>> You have a problem of context - if you have multiple monitors, how do
>>> you know which to send the error back to if you're not in the event
>>> loop thread, and thus cur_mon is NULL. With Marc-Andre's series which
>>> allows proper async command processing it gets even harder, because
>>> there's potentially many outstanding commands associated with a monitor
>>> and you need to decide which the error should be given to.
>>
>> Why should it even consult the current monitor?  Shouldn't errors go to
>> all HMP monitors when QEMU falls back to error_report?
> 
> Maybe.  Copying error_report() output to human monitors is a courtesy to
> users who fail to watch stderr.  But what about QMP?  I figure all we
> could do there is sending some "Uh, here's an error message that may or
> may not be related to anything you've been doing in this monitor, do
> with it what you want" event.  Would that be useful?
> 
> Also, when you got an HMP monitor and stderr on the same tty (or
> whatever), you'd want to suppress one of the two messages.

If you have an HMP monitor you wouldn't print to stderr---stderr would
be reserved for the case where there are only QMP monitors.

Paolo