netmap_idx_n2k
kring->nr_hwtail = nm_prev(netmap_idx_n2k(kring, nic_i), lim);
nm_i = netmap_idx_n2k(kring, nic_i);
int l = netmap_idx_n2k(na->tx_rings[0], i);
uint32_t nm_i = netmap_idx_n2k(na->rx_rings[0], nic_i);
kring->nr_hwtail = nm_prev(netmap_idx_n2k(kring, nic_i), lim);
nm_i = netmap_idx_n2k(kring, nic_i);
int si = netmap_idx_n2k(na->tx_rings[txq->ift_id], i);
nm_i = netmap_idx_n2k(kring, nic_i);