Well, just "Device > Load" in K3b made KDE notify me about a blank DVD again (as before).
Only this was added to dmesg (the clocksource message has been there before "Load" already):
[ 3912.648032] Clocksource tsc unstable (delta = -231260494 ns)
[ 4306.359731] cdrom: This disc doesn't have any tracks I recognize!
Well, just "Device > Load" in K3b made KDE notify me about a blank DVD again (as before).
Only this was added to dmesg (the clocksource message has been there before "Load" already):
[ 3912.648032] Clocksource tsc unstable (delta = -231260494 ns)
[ 4306.359731] cdrom: This disc doesn't have any tracks I recognize!