VGE_BUFLEN
htole16(VGE_BUFLEN(map->dm_segs[0].ds_len) | VGE_RXDESC_I);
f->tf_buflen = htole16(VGE_BUFLEN(map->dm_segs[seg].ds_len));
f->tf_buflen = htole16(VGE_BUFLEN(ETHER_PAD_LEN - sz));