XEN_NETIF_NR_SLOTS_MIN
#define XEN_NETBK_LEGACY_SLOTS_MAX XEN_NETIF_NR_SLOTS_MIN
int max = XEN_NETIF_NR_SLOTS_MIN + (rx->status <= RX_COPY_THRESHOLD);
(NET_TX_RING_SIZE - XEN_NETIF_NR_SLOTS_MIN - 1);
#define NET_RX_SLOTS_MIN (XEN_NETIF_NR_SLOTS_MIN + 1)