Well-known ioctl Interfaces

Many ioctl(9E) operations are common to a class of device drivers. For example, most disk drivers implement many of the dkio(7I) family of ioctl()s. Many of these interfaces copy in or copy out data structures from the kernel, and some of these data structures have changed size in the LP64 data model. The following section lists the ioctls that now require explicit conversion in 64-bit driver ioctl routines for the dkio, fdio(7I), fbio(7I), cdio(7I), and mtio(7I) families of ioctl()s.

ioctl command	Affected data structure	Reference
DKIOCGAPART DKIOCSAPART	struct dk_map struct dk_allmap	dkio(4)
DKIOGVTOC DKIOSVTOC	struct partition struct vtoc	dkio(4)
FBIOPUTCMAP FBIOGETCMAP	struct fbcmap	fbio(4)
FBIOPUTCMAPI FBIOGETCMAPI	struct fbcmap_i	fbio(4)
FBIOSCURSOR FBIOSCURSOR	struct fbcursor	fbio(4)
CDROMREADMODE1 CDROMREADMODE2	struct cdrom_read	cdio(4)
CDROMCDDA	struct cdrom_cdda	cdio(4)
CDROMCDXA	struct cdrom_cdxa	cdio(4)
CDROMSUBCODE	struct cdrom_subcode	cdio(4)
FDIOCMD	struct fd_cmd	fdio(4)
FDRAW	struct fd_raw	fdio(4)
MTIOCTOP	struct mtop	mtio(4)
MTIOCGET	struct mtget	mtio(4)
MTIOCGETDRIVETYPE	struct mtdrivetype_request	mtio(4)
USCSICMD	struct uscsi_cmd	scsi(4)

Device Sizes

The nblocks property is exported by each slice of a block device driver. It contains the number of 512 byte blocks that each slice of the device can support. The nblocks property is defined as a signed 32-bit quantity, which limits the maximum size of a slice to 1 Tbyte.

Disk devices that provide more than 1 Tbyte of storage per disk must define the Nblocks property, which should still contain the number of 512 byte blocks that the device can support. However, Nblocks is a signed 64-bit quantity, which removes any practical limit on disk space.

The nblocks property is now deprecated; all disk devices should provide the Nblocks property.