MLX_V4_FWERROR
#define MLX_V4_GET_FWERROR(sc) bus_read_1 (sc->mlx_mem, MLX_V4_FWERROR)
#define MLX_V4_PUT_FWERROR(sc, val) bus_write_1(sc->mlx_mem, MLX_V4_FWERROR, val)