cd(9)

NAME

cd - CDROM driver for the CAM SCSI subsystem

DESCRIPTION

The cd device driver provides a read only interface for

CDROM drives
(SCSI type 5) and WORM drives (SCSI type 4) that support

CDROM type commands. Some drives do not behave as the driver expects.

See the QUIRKS
section for information on possible flags.

QUIRKS

Each CD-ROM device can have different interpretations of the

SCSI spec.
This can lead to drives requiring special handling in the

driver. The
following is a list of quirks that the driver recognize.

CD_Q_NO_TOUCH This flag tell the driver not to probe the

drive at

attach time to see if there is a disk in

the drive and
find out what size it is. This flag is

currently unimplemented in the CAM cd driver.

CD_Q_BCD_TRACKS This flag is for broken drives that return

the track

numbers in packed BCD instead of straight

decimal. If
the drive seems to skip tracks (tracks

10-15 are
skipped) then you have a drive that is in

need of this
flag.

CD_Q_NO_CHANGER This flag tells the driver that the device

in question

is not a changer. This is only necessary

for a CDROM
device with multiple luns that are not a

part of a
changer.

CD_Q_CHANGER This flag tells the driver that the given

device is a

multi-lun changer. In general, the driver

will figure
this out automatically when it sees a LUN

greater than
0. Setting this flag only has the effect

of telling the
driver to run the initial read capacity

command for LUN
0 of the changer through the changer

scheduling code.

CD_Q_10_BYTE_ONLY
This flag tells the driver that the given

device only
accepts 10 byte MODE SENSE/MODE SELECT com

mands. In
general these types of quirks should not be

added to the
cd(4) driver. The reason is that the driv

er does several things to attempt to determine whether

the drive in
question needs 10 byte commands. First, it

issues a CAM
Path Inquiry command to determine whether

the protocol
that the drive speaks typically only allows

10 byte commands. (ATAPI and USB are two prominent

examples of
protocols where you generally only want to

send 10 byte
commands.) Then, if it gets an ILLEGAL RE

QUEST error
back from a 6 byte MODE SENSE or MODE SE

LECT command, it
attempts to send the 10 byte version of the

command
instead. The only reason you would need a

quirk is if
your drive uses a protocol (e.g., SCSI)

that typically
does not have a problem with 6 byte com

mands.

FILES

/sys/cam/scsi/scsi_cd.c is the driver source file.

SEE ALSO

cd(4), scsi(4)

HISTORY

The cd manual page first appeared in FreeBSD 2.2.

AUTHORS

This manual page was written by John-Mark Gurney <gur

ney_j@efn.org>. It
was updated for CAM and FreeBSD 3.0 by Kenneth Merry

<ken@FreeBSD.org>.

BSD September 2, 2003

BSD