mlx5_wqe_eth_pad
size += sizeof(struct mlx5_wqe_eth_pad) +
struct mlx5_wqe_eth_pad *pad;
memset(pad, 0, sizeof(struct mlx5_wqe_eth_pad));
seg += sizeof(struct mlx5_wqe_eth_pad);
size += sizeof(struct mlx5_wqe_eth_pad) / 16;