RING_GET_REQUEST
rxreq = RING_GET_REQUEST(&xnbp->xnb_rx_ring, loop);
rxresp->id = RING_GET_REQUEST(&xnbp->xnb_rx_ring, prod)->id;
txreq = RING_GET_REQUEST(&xnbp->xnb_tx_ring, loop);
RING_GET_REQUEST(&xnbp->xnb_tx_ring, loop);
txreq = RING_GET_REQUEST(&xnbp->xnb_tx_ring, txp->xt_idx);
rxreq = RING_GET_REQUEST(&xnbp->xnb_rx_ring, loop);
rxresp->id = RING_GET_REQUEST(&xnbp->xnb_rx_ring, prod)->id;
txrp = RING_GET_REQUEST(&xnfp->xnf_tx_ring, slot);
RING_GET_REQUEST(&xnfp->xnf_tx_ring, slot + 1);
txrp = RING_GET_REQUEST(&xnfp->xnf_tx_ring, slot);
RING_GET_REQUEST(&xnfp->xnf_tx_ring, slot);
reqp = RING_GET_REQUEST(&xnfp->xnf_rx_ring,
hang_ix = (RING_IDX) (reqp - RING_GET_REQUEST(&xnfp->xnf_rx_ring, 0));
target = RING_GET_REQUEST(uring, uring->req_prod_pvt);