How can I set timeout limits on root device searching when booting?

["cunshunxia" <505481172@xxxxxx>]

With 'e' pressed at boot menu, I set the `root=UUID=[wrong UUID]` in boot cmdline. Then I expect that I will run into emergency mode.

However, boot log stuck at `Job dev-disk-by\x2duuid-XXXX-device/start running(5min 10s/ no limit)`.

I tried DefaultDeviceTimeoutSec=90s, but it doesn't work.

In addition, if I set a wrong uuid of root device in fstab, the system will boot up with read-only filesystem instead of running into emergency mode even if I didn't set 'nofail'.

Is there any way that I can set the timeoutsec or how can I run into emergency mode if root device is set incorrectly?