MAX_RX_PAGES
#define MAX_RX_BD_AVAIL (MAX_RX_PAGES * TOTAL_RX_BD_PER_PAGE)
#define MAX_PG_PAGES (MAX_RX_PAGES * 4)
bus_dmamap_t rx_bd_chain_map[MAX_RX_PAGES];
struct rx_bd *rx_bd_chain[MAX_RX_PAGES];
bus_addr_t rx_bd_chain_paddr[MAX_RX_PAGES];