add: nv_acc_assert_fifo();
context: status_t ACQUIRE_ENGINE(uint32 capabilities, uint32 max_wait, sync_token *st, engine_token **et){	/* acquire the shared benaphore */	AQUIRE_BEN(si->engine.lock)	/* sync if required */	if (st) SYNC_TO_TOKEN(st);	/* return an engine token */	*et = &nv_engine_token;	return B_OK;}