[libvirt] Selective block device migration implementation

Dear Libvirt Developers, I'm working to implement feature request [1]. The feature request proposes to enhance `libvirt' code so the API caller can specify which block devices are to be migrated using e.g. parameters in the `virDomainMigrateToURI3' call. There is the following issues: 1. It is obvious to identify devices to be migrated using the `device_name'. However, these need to be serialized in either 1) a comma-separated string or in 2) a set of values named like `blockdevice%d' with `blockdevice' value holding amount of block devices to migrate. What is the desired approach here? Can block device name contain commas or should I neglect this possibility? 2. `libvirt' behavior in block devices migration was copied from the `QEMU' implementation that ignores read-only devices as well. So, `libvirt' code will need to pass this list to `QEMU' `migrate' QMP command and this argument should be implemented in the `QEMU'. Is there any implementation advices from your side? Pavel [1] https://bugzilla.redhat.com/show_bug.cgi?id=1203032