cdrom(HW)

cdrom: Srom, cdt -- compact disk devices

Description

Srom is the SCSI peripheral driver for CD-ROM devices (compact disk drives).

The cdt (CD tape) driver overlays Srom to provide a cartridge tape-like interface. Data on the CD-ROM can then be accessed using utilities normally used to access a cartridge or SCSI tape. This technology is used for reading older installation CDs.

The command mkdev cdrom is used to configure the CD-ROM driver interactively. This defines the SCSI host adapter, controller target ID, and device LUN in the SCSI configuration file mscsi(F).

The CD-ROM device driver does not print its configuration message until the first open of a CD-ROM drive after a reboot of the system.

The character special device files (/dev/rcd) support raw I/O in multiples of the physical sector size of the CD-ROM (typically 2KB).

The block special CD device files (/dev/cd) support buffered I/O and enable a CD-ROM to be mounted as an HS filesystem. See mount(ADM) for details of the features of High Sierra, Rock Ridge, and ISO 9660 CD-ROM formats that are supported.

The minor device number determines which compact disk unit will be accessed; minor number 0 accesses the first device, 1 the second device and so on, up to minor number 255.

Boot time configuration of SCSI

The Srom driver supports the Srom.ten bootstring(HW), which forces the driver to support 10-byte SCSI read commands. By default, the driver supports 6-byte read commands, which are sufficient for devices of 1Gb or less. Contact your hardware vendor about your device's read command requirements.

Diagnostics

The following error messages may be displayed on the console. See messages(M) for general information about kernel error messages, including a list of generic device driver errors.

Srom -- SCSI CD-ROM device driver

NOTICE: Srom: Spurious interrupt

No command was pending when an interrupt was received.

cdt -- tape emulator for SCSI CD-ROM driver

CONFIG: cdt: Block device name (--/minor) driver not installed

The major device number corresponding to the underlying physical device could not be calculated.

CONFIG: cdt: Device name unit m (cdt_unitnum) not CD-ROM tape unit n

The underlying physical device must be a CD-ROM drive.

WARNING: cdt: Unrecognized data format on dev device (major/minor)

The data format on the disk was not recognized.

Limitations

A CD-ROM is a read-only device.

Files

/dev/cdn: block special device for CD-ROM drive number n
/dev/rcdn: character (raw) special device for CD-ROM drive number n
/dev/nrcdtn: no rewind character (raw) special device for CD-ROM tape driver on drive number n
/dev/rcdtn: rewind character (raw) special device for CD-ROM tape driver on drive number n
/dev/xcdtn: control special device for CD-ROM tape driver on drive number n