From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=34315 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1Pce0z-0007Zo-FD for qemu-devel@nongnu.org; Tue, 11 Jan 2011 08:11:58 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Pce0y-0004Iz-Af for qemu-devel@nongnu.org; Tue, 11 Jan 2011 08:11:57 -0500 Received: from mx1.redhat.com ([209.132.183.28]:19442) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Pce0y-0004Ij-3o for qemu-devel@nongnu.org; Tue, 11 Jan 2011 08:11:56 -0500 Date: Tue, 11 Jan 2011 11:11:48 -0200 From: Luiz Capitulino Message-ID: <20110111111148.1b94b4a4@doriath> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Subject: [Qemu-devel] RFC: QMP event notification for disk media eject List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: kwolf@redhat.com, stefanha@gmail.com, Markus Armbruster 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 - new file path (to allow distinguishing eject from change) 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" }, ... }