研究了linux自动mknod

特别是 mtd 这部分，确实长见识啊！

snprintf(gd->disk_name, sizeof(gd->disk_name),
"%s%c", tr->name, (tr->part_bits?'a':'0') + new->devnum);
snprintf(gd->devfs_name, sizeof(gd->devfs_name),
"%s/%c", tr->name, (tr->part_bits?'a':'0') + new->devnum);