124 lines
4.2 KiB
Groff
124 lines
4.2 KiB
Groff
.\" Copyright (c) 1997
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.\" John-Mark Gurney. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY John-Mark Gurney AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd March 25, 2014
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.Dt CD 9
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.Os
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.Sh NAME
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.Nm cd
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.Nd CDROM driver for the CAM SCSI subsystem
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.Sh DESCRIPTION
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The
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.Nm
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device driver provides a read only interface for CDROM drives
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.Tn ( SCSI
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type 5)
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and WORM drives
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.Tn ( SCSI
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type 4)
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that support CDROM type commands.
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Some drives do not behave as the driver expects.
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See the
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.Sx QUIRKS
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section for information on possible flags.
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.Sh QUIRKS
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Each
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.Tn CD-ROM
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device can have different interpretations of the
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.Tn SCSI
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spec.
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This can lead to drives requiring special handling in the driver.
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The following is a list of quirks that the driver recognize.
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.Bl -tag -width CD_Q_BCD_TRACKS
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.It Dv CD_Q_NO_TOUCH
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This flag tells the driver not to probe the drive at attach time to see if
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there is a disk in the drive and find out what size it is.
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This flag is currently unimplemented in the CAM
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.Nm
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driver.
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.It Dv CD_Q_BCD_TRACKS
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This flag is for broken drives that return the track numbers in packed BCD
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instead of straight decimal.
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If the drive seems to skip tracks
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(tracks 10-15 are skipped)
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then you have a drive that is in need of this flag.
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.It Dv CD_Q_NO_CHANGER
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This flag tells the driver that the device in question is not a changer.
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This is only necessary for a CDROM device with multiple luns that are not a
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part of a changer.
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.It Dv CD_Q_CHANGER
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This flag tells the driver that the given device is a multi-lun changer.
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In general, the driver will figure this out automatically when it sees a
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LUN greater than 0.
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Setting this flag only has the effect of telling the
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driver to run the initial read capacity command for LUN 0 of the changer
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through the changer scheduling code.
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.It Dv CD_Q_10_BYTE_ONLY
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This flag tells the driver that the given device only accepts 10 byte MODE
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SENSE/MODE SELECT commands.
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In general these types of quirks should not be
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added to the
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.Xr cd 4
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driver.
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The reason is that the driver does several things to attempt to
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determine whether the drive in question needs 10 byte commands.
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First, it
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issues a CAM Path Inquiry command to determine whether the protocol that
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the drive speaks typically only allows 10 byte commands.
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(ATAPI and USB
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are two prominent examples of protocols where you generally only want to
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send 10 byte commands.)
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Then, if it gets an ILLEGAL REQUEST error back
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from a 6 byte MODE SENSE or MODE SELECT command, it attempts to send the 10
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byte version of the command instead.
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The only reason you would need a
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quirk is if your drive uses a protocol (e.g.,
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.Tn SCSI )
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that typically does not have a problem with 6 byte commands.
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.El
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.Sh FILES
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.Bl -tag -width /sys/cam/scsi/scsi_cd.c -compact
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.It Pa /sys/cam/scsi/scsi_cd.c
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is the driver source file.
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.El
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.Sh SEE ALSO
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.Xr cd 4 ,
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.Xr scsi 4
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.Sh HISTORY
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The
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.Nm
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manual page first appeared in
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.Fx 2.2 .
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.Sh AUTHORS
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.An -nosplit
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This
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manual page was written by
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.An John-Mark Gurney Aq jmg@FreeBSD.org .
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It was updated for CAM and
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.Fx 3.0
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by
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.An Kenneth Merry Aq ken@FreeBSD.org .
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