Comment # 40 on bug 84500 from Alexandre Demers

(In reply to drago01 from comment #39)
> I am seeing those messages too here:
> 
> radeon 0000:02:00.0: Packet0 not allowed!
> 
> on a R9 270X ... no hangs or anything else just the message in the log
> (3.17.3 / mesa 10.3.3 on F20).

I haven't hit it for a while. But I'm testing a 3.18 kernel with latest mesa
from git. This could be a clue.