get_kernel
static error_t get_kernel(menu_t *, menu_cmd_t, char *, size_t);
ret = get_kernel(mp, KERNEL_CMD, kernbuf, sizeof (kernbuf));
ret = get_kernel(mp, ARGS_CMD, args_buf,
ret = get_kernel(mp, ARGS_CMD, args_buf,
rv = get_kernel(mp, optnum, buf, sizeof (buf));