RX_BUF_ALLOC_SIZE
#define RX_BUF_ALLOC_SIZE (ETH_FRAME_LEN + (64 * 3))
#define RX_BUF_ALLOC_SIZE(gp) ((gp)->rx_buf_sz + 28 + RX_OFFSET + 64)
#define RX_BUF_ALLOC_SIZE (1546 + RX_OFFSET + 64)