MIN_SQ_DESC_PER_PKT_XMIT
sq->br = buf_ring_alloc(q_len / MIN_SQ_DESC_PER_PKT_XMIT, M_DEVBUF,
subdesc_cnt = MIN_SQ_DESC_PER_PKT_XMIT + nsegs - 1;
((SND_QUEUE_LEN / MIN_SQ_DESC_PER_PKT_XMIT) * MAX_CQE_PER_PKT_XMIT)