[libvirt] Re: [Qemu-devel] [PATCH 1/6] Allow multiple monitor devices (v2)
Anthony Liguori wrote:
Right now only one monitor device can be enabled at a time. In order
to support
asynchronous notification of events, I would like to introduce a 'wait' command
that waits for an event to occur. This implies that we need an additional
monitor session to allow commands to still be executed while waiting for an
asynchronous notification.
I think this is race prone. For example:
monitor 1: wait
monitor 2: hotunplug dev1
monitor 2: hotplug dev1
monitor 1: event
there is no way to tell whether event (which relates to dev1) happened
the hotunplug or after the hotunplug. In general there is no way to
correlate events to commands.
What's wrong with having async notifications? Sure, we'll need to make
sure notifications don't mix with command responses, and that all
commands are acked (the (qemu) prompt serves that purpose now), but it
seems to me do be a lot easier for the management end.
Multiple monitors would still come in useful for debugging in a managed
environment.
--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.