While we want machine interfaces like -blockdev and QMP blockdev-add to add as little auto-detection as possible so that management tools are explicit about their needs, -drive is a convenience option for human users. Enabling auto-read-only=on by default there enables users to use read-only images for read-only guest devices without having to specify read-only=on explicitly. If they try to attach the image to a read-write device, they will still get an error message.
Signed-off-by: Kevin Wolf <kw...@redhat.com> --- blockdev.c | 1 + 1 file changed, 1 insertion(+) diff --git a/blockdev.c b/blockdev.c index a8755bd908..ab57a8a53a 100644 --- a/blockdev.c +++ b/blockdev.c @@ -590,6 +590,7 @@ static BlockBackend *blockdev_init(const char *file, QDict *bs_opts, qdict_set_default_str(bs_opts, BDRV_OPT_CACHE_NO_FLUSH, "off"); qdict_set_default_str(bs_opts, BDRV_OPT_READ_ONLY, read_only ? "on" : "off"); + qdict_set_default_str(bs_opts, BDRV_OPT_AUTO_READ_ONLY, "on"); assert((bdrv_flags & BDRV_O_CACHE_MASK) == 0); if (runstate_check(RUN_STATE_INMIGRATE)) { -- 2.19.1