If readonly=on is given at device creation time, the ->readonly flag needs to be set in the block driver state for this device so that readonly-ness is preserved across media changes (qmp change command). Similarly, to preserve the snapshot property requires ->open_flags to be correct. Signed-off-by: Kevin Shanahan <kmshanah(a)disenchant.net&gt; --- blockdev.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/blockdev.c b/blockdev.c index 8669142..84f9a2e 100644 --- a/blockdev.c +++ b/blockdev.c @@ -526,6 +526,8 @@ DriveInfo *drive_init(QemuOpts *opts, int default_to_scsi) if_name[type], mediastr, unit_id); } dinfo->bdrv = bdrv_new(dinfo->id); + dinfo->bdrv->open_flags = snapshot ? BDRV_O_SNAPSHOT : 0; + dinfo->bdrv->read_only = ro; dinfo->devaddr = devaddr; dinfo->type = type; dinfo->bus = bus_id; -- 1.7.12