search for: number_of_following_command

...or gallium. If it plays just a barrier, I guess it should work by something like (in case of m2mf): BEGIN_RING(chan, m2mf, 0x110, 1); OUT_RING(chan, 1); Otherwise, it may actually play to serialize some commands, then I would rather use as follows: BEGIN_RING(chan, m2mf, 0x110, 1); OUT_RING(chan, NUMBER_OF_FOLLOWING_COMMANDS); I have tried both approaches, and the application runs without any problems, but I am not sure if barriers have happened or not ;-) I would appreciate if anyone can tell me how to use the barrier command. Best, - Shinpei