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NAME    [Toc]    [Back]

     cd -- CDROM driver for the CAM SCSI subsystem

DESCRIPTION    [Toc]    [Back]

     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 don't behave as the driver expects.  See the QUIRKS
     section for information on possible flags.

QUIRKS    [Toc]    [Back]

     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

     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

     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.

		      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 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 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
		      doesn't have a problem with 6 byte commands.

FILES    [Toc]    [Back]

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

SEE ALSO    [Toc]    [Back]

     cd(4), scsi(4)

HISTORY    [Toc]    [Back]

     The cd manual page first appeared in FreeBSD 2.2.

AUTHORS    [Toc]    [Back]

     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 5.2.1		       September 2, 2003		 FreeBSD 5.2.1
[ Back ]
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