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CD(9)		       FreeBSD Kernel Developer's Manual		 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 com-
     mands.  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	unim-
		      plemented	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 commands.	In
		      general these types of quirks should not be added	to the
		      cd(4) driver.  The reason	is that	the driver does	sev-
		      eral 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 com-
		      mands.  (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 REQUEST error
		      back from	a 6 byte MODE SENSE or MODE SELECT 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 commands.

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

FreeBSD	10.1		       September 2, 2003		  FreeBSD 10.1

NAME | DESCRIPTION | QUIRKS | FILES | SEE ALSO | HISTORY | AUTHORS

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<http://www.freebsd.org/cgi/man.cgi?query=cd&sektion=9&manpath=FreeBSD+9.0-RELEASE>

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