IAVF_RX_DESC
prefetch(IAVF_RX_DESC(rx_ring, ntc));
rx_desc = IAVF_RX_DESC(rx_ring, rx_ring->next_to_clean);
rx_desc = IAVF_RX_DESC(rx_ring, ntu);
rx_desc = IAVF_RX_DESC(rx_ring, 0);
(n) = IAVF_RX_DESC((r), (i)); \