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CD(9)                  FreeBSD Kernel Developer's Manual                 CD(9)

     cd - CDROM driver for the CAM SCSI subsystem

     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
     section QUIRKS for info on possible flags.

     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.  See scsiconf(9)
     for more information on how to add quirk entries.

     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.

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

     cd(4), scsi(4)

     The cd manual page first appeared in FreeBSD 2.2.

     This manual page was written by John-Mark Gurney <>.  It
     was updated for CAM and FreeBSD 3.0 by Kenneth Merry <>.

FreeBSD 11.0-PRERELEASE        October 10, 1998        FreeBSD 11.0-PRERELEASE


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