Hi
On Fri, Jun 21, 2013 at 1:57 PM, Paolo Bonzini <pbonz...@redhat.com> wrote: > > > > What exactly are you trying to do here (I guess I'll understand more > > when I get to the later patches)? > > > > Getting to the bottom BlockDriverState to be able to eject & change it. > > (it could also be named the "parent", but other parts of the code > > suggest the "child" name) > > There is already an interface for eject/change, which is the monitor. > To signal an eject or medium change, the SPICE client should simply ask > libvirt to do so. It is fine to change "from" spicebd: "to" spicebd:, > the guest would still perceive it as a change. > > I'm not sure how libvirt communicates the change back to the SPICE > client, and whether it is asynchronous or synchronous. > > Spice is not using libvirt, and doesn't have access to monitor. I looked at the monitor code. Basically, the spice block driver I proposed uses a similar code to forcefully eject and change. Perhaps it's possible for the Spice qemu-side code to have access to the monitor, but the end result would be similar anyway. > BTW, note that IDE or virtio-blk do not support removable media, and are > not able to pass eject or media change notifications. SCSI devices > (such as usb-bot, usb-uas and virtio-scsi) can. > > > Can you draw the relationships between all the BlockDriverStates in a > > spicebd: drive? > > > > > > Hopefully, but I have only tested with raw images (w/wo snapshot). > > Then draw it. :) But from the above description it looks like it is not > necessary, it should simply be "raw" on top of "spicebd". Parsing > formats should be done on the client side, perhaps by invoking qemu-nbd > and tunnelling the NBD data on the SPICE channel. > > Right, "raw" on top of "spicebd" for iso/raw images (and "qcow2" on top for snapshot support - even in readonly). I wonder what would happen if spicebd image would be something else than raw/iso, I suppose there would be more BlockDriverStates to handle the various format. -- Marc-André Lureau
