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CD(9) BSD 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 at- tach 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 in- stead. 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>. BSD September 2, 2003 BSD
NAME | DESCRIPTION | QUIRKS | FILES | SEE ALSO | HISTORY | AUTHORS
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