__dev_t
char *devname(__dev_t, __mode_t);
char *devname_r(__dev_t, __mode_t, char *, int);
__dev_t st_dev; /* inode's device */
__dev_t st_rdev; /* device type */
__dev_t st_dev; /* inode's device */
__dev_t st_rdev; /* device type */
typedef __dev_t dev_t;
typedef __dev_t dev_t; /* device number or struct cdev */