TXQ_COMMAND
if (rdlp(mp, TXQ_COMMAND) & (1 << txq->index))
~(rdlp(mp, TXQ_COMMAND) & 0xff);
wrlp(mp, TXQ_COMMAND, 1 << txq->index);
wrlp(mp, TXQ_COMMAND, mask << 8);
while (rdlp(mp, TXQ_COMMAND) & mask)