With -blockdev or when reusing externally created images and thus without the need for formatting the image we actually can support snapshots of read-only disks. Arguably it's not very useful so they are not done by default but users of libvirt such as oVirt are actually using this. https://bugzilla.redhat.com/show_bug.cgi?id=1832204 Signed-off-by: Peter Krempa <pkrempa@xxxxxxxxxx> --- src/qemu/qemu_driver.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c index 1c7c87128d..29d964f1e8 100644 --- a/src/qemu/qemu_driver.c +++ b/src/qemu/qemu_driver.c @@ -14683,7 +14683,7 @@ qemuDomainSnapshotPrepareDiskExternal(virDomainDiskDefPtr disk, int err; int rc; - if (disk->src->readonly) { + if (disk->src->readonly && !(reuse || blockdev)) { virReportError(VIR_ERR_CONFIG_UNSUPPORTED, _("external snapshot for readonly disk %s " "is not supported"), disk->dst); -- 2.26.2
