idmac_desc_64addr
struct idmac_desc_64addr *p;
DESC_RING_BUF_SZ / sizeof(struct idmac_desc_64addr);
(sizeof(struct idmac_desc_64addr) *
(sizeof(struct idmac_desc_64addr) *
struct idmac_desc_64addr *desc_first, *desc_last, *desc;