Am 12.01.2016 um 15:59 hat Paolo Bonzini geschrieben: > > > On 12/01/2016 15:16, Kevin Wolf wrote: > >> Thus we should avoid selection of "pflash" drives for VM state saving. > >> > >> For now "pflash" is read-write raw image as it configured by libvirt. > >> Thus there are no such images in the field and we could safely disable > >> ability to save state to those images inside QEMU. > > > > This is obviously broken. If you write to the pflash, then it needs to > > be snapshotted in order to keep a consistent state. > > > > If you want to avoid snapshotting the image, make it read-only and it > > will be skipped even today. > > Sort of. The point of having flash is to _not_ make it read-only, so > that is not a solution. > > Flash is already being snapshotted as part of saving RAM state. In > fact, for this reason the device (at least the one used with OVMF; I > haven't checked other pflash devices) can simply save it back to disk > on the migration destination, without the need to use "migrate -b" or > shared storage. > [...] > I don't like very much using IF_PFLASH this way, which is why I hadn't > replied to the patch so far---I hadn't made up my mind about *what* to > suggest instead, or whether to just accept it. However, it does work. > > Perhaps a separate "I know what I am doing" skip-snapshot option? Or > a device callback saying "not snapshotting this is fine"?
Boy, is this ugly... What do you do with disk-only snapshots? The recovery only works as long as you have VM state. Kevin
