On Tue, 11 Jan 2011 14:28:23 +0100 Kevin Wolf <kw...@redhat.com> wrote:
> Am 11.01.2011 14:11, schrieb Luiz Capitulino: > > Hi there, > > > > I need feedback on a new QMP event. > > > > Problem > > ======= > > > > There's no way for a management tool to detect that a guest OS has ejected > > the > > media in a CDROM or Floppy disk drive (I'm discarding polling, because it's > > undesirable at best). > > > > The end result is that the management tool can get confused, this is > > happening > > with libvirt when migration is involved: if the guest is saved/restored or > > migrated, then libvirt will start the guest again with media still present. > > > > NOTE: Most of the analysis here was done by Daniel Berrange. > > > > Solution > > ======== > > > > We need a new QMP event to solve that. There are two possible events, a > > general one and a very specific one. > > > > There are 3 scenarios in which both events should be emitted: > > > > 1. When guest OS ejects media > > 2. When 'eject' monitor command is run > > 3. When 'change' monitor command is run > > > > BLOCK_MEDIA_CHANGE > > ------------------ > > > > This is the general event, it's emitted when any removable block device > > is changed. > > > > Ideally, the event should contain two pieces of info: > > > > - qdev device name > > Is there a reason why you use the device name instead of the drive > name/blockdev ID here? Good question, this is a copy & paste from Daniel initial request, so he's the best person to answer that question. > > - new file path (to allow distinguishing eject from change) > > How do you distinguish? Would this key be missing for ejects? An empty > string? Something else? Yes, I think it would be optional and thus only part of the change command. > > Example: > > > > { "event": "BLOCK_MEDIA_CHANGE", "data": { "qdev-id": "myid", > > "new-path": > > "/foo/bar/dir/distro.iso" }, > > ... } > > > > BLOCK_MEDIA_EJECT > > ----------------- > > > > This event is only emitted when a CDROM or a floppy disk is ejected. > > > > The event contains one info one: > > > > - device name > > > > Example: > > > > { "event": "BLOCK_MEDIA_EJECT", "data": { "device-name": "ide1-cd0" }, > > ... } > > I think it's called drive name in most other places. Ok, please note that we won't implement both events, we have to choose one or the other.