Writing Device Drivers
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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 ioctls. 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 ioctlsthat now require explicit conversion in 64-bit driver ioctl routines for the dkio, fdio(7I), fbio(7I), cdio(7I), and mtio(7I) families of ioctls.

ioctl command

Affected data structure

Reference

DKIOCGAPART

DKIOCSAPART

dk_map

dk_allmap

dkio(7I)

DKIOGVTOC

DKIOSVTOC

partition

vtoc

dkio(7I)

FBIOPUTCMAP

FBIOGETCMAP

fbcmap

fbio(7I)

FBIOPUTCMAPI

FBIOGETCMAPI

fbcmap_i

fbio(7I)

FBIOCCURSOR

FBIOSCURSOR

fbcursor

fbio(7I)

CDROMREADMODE1

CDROMREADMODE2

cdrom_read

cdio(7I)

CDROMCDDA

cdrom_cdda

cdio(7I)

CDROMCDXA

cdrom_cdxa

cdio(7I)

CDROMSUBCODE

cdrom_subcode

cdio(7I)

FDIOCMD

fd_cmd

fdio(7I)

FDRAW

fd_raw

fdio(7I)

MTIOCTOP

mtop

mtio(7I)

MTIOCGET

mtget

mtio(7I)

MTIOCGETDRIVETYPE

mtdrivetype_request

mtio(7I)

USCSICMD

uscsi_cmd

scsi_free_consistent_buf(9F)

Device Sizes

The nblocks property is exported by each slice of a block device driver. This property 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.

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