DKIOC
#define DKIOCGGEOM (DKIOC|1) /* Get geometry */
#define DKIOCINFO (DKIOC|3) /* Get info */
#define DKIOCEJECT (DKIOC|6) /* Generic 'eject' */
#define DKIOCGVTOC (DKIOC|11) /* Get VTOC */
#define DKIOCSVTOC (DKIOC|12) /* Set VTOC & Write to Disk */
#define DKIOCFLUSHWRITECACHE (DKIOC|34) /* flush cache to phys medium */