2d8eb2c034
This includes a description of the changer timeout kernel options and sysctl variables. I didn't check to make sure the ioctl descriptions are up to date; that will come sometime later. (The ioctls haven't changed in the CAM driver, but I'm not sure if the man page was in sync with even the old driver.)
477 lines
14 KiB
Groff
477 lines
14 KiB
Groff
.\" Copyright (c) 1996
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.\" Julian Elischer <julian@freebsd.org>. 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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.\"
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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 THE AUTHOR 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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.\" $Id: cd.4,v 1.11 1997/03/21 20:13:23 mpp Exp $
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.\"
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.Dd October 10, 1998
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.Dt CD 4
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.Os FreeBSD
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.Sh NAME
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.Nm cd
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.Nd SCSI CD-ROM driver
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.Sh SYNOPSIS
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.Cd device cd
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.Cd device cd1 at scbus0 target 4 lun 0
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.Cd options "CHANGER_MIN_BUSY_SECONDS=3"
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.Cd options "CHANGER_MAX_BUSY_SECONDS=11"
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.Sh DESCRIPTION
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The
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.Nm cd
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driver provides support for a
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.Tn SCSI
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.Tn CD-ROM
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(Compact Disc-Read Only Memory) drive.
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In an attempt to look like a regular disk, the
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.Nm
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driver synthesizes a partition table, with one partition covering the entire
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.Tn CD-ROM .
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It is possible to modify this partition table using
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.Xr disklabel 8 ,
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but it will only last until the
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.Tn CD-ROM
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is unmounted.
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In general the interfaces are similar to those described by
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.Xr wd 4
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and
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.Xr da 4 .
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.Pp
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As the
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.Tn SCSI
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adapter is probed during boot, the
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.Tn SCSI
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bus is scanned for devices. Any devices found which answer as CDROM
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(type 5) or WORM (type 4) type devices will be `attached' to the
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.Nm
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driver.
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Prior to
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.Fx 2.1 ,
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the first device found will be attached as
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.Li cd0
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the next,
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.Li cd1 ,
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etc.
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Beginning in
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.Fx 2.1
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it is possible to specify what cd unit a device should
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come on line as; refer to
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.Xr scsi 4
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for details on kernel configuration.
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.Pp
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The system utility
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.Xr disklabel 8
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may be used to read the synthesized
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disk label
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structure, which will contain correct figures for the size of the
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.Tn CD-ROM
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should that information be required.
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.Pp
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.Sh KERNEL CONFIGURATION
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Any number of
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.Tn CD-ROM
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devices may be attached to the system regardless of system
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configuration as all resources are dynamically allocated.
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.Sh IOCTLS
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The following
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.Xr ioctl 2
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calls which apply to
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.Tn SCSI
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.Tn CD-ROM
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drives are defined
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in the header files
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.Aq Pa sys/cdio.h
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and
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.Aq Pa sys/disklabel.h .
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.Pp
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.Bl -tag -width CDIOCREADSUBCHANNEL -compact
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.It Dv DIOCGDINFO
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.It Dv DIOCSDINFO
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.Pq Li "struct disklabel"
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Read or write the in-core copy of the disklabel for the
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drive. The disklabel is initialized with information
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read from the scsi inquiry commands, and should be the same as
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the information printed at boot. This structure is defined in
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.Xr disklabel 5 .
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.It Dv CDIOCCAPABILITY
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.Pq Li "struct ioc_capability"
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Retrieve information from the drive on what features it supports. The
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information is returned in the following structure:
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.Bd -literal -offset indent
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struct ioc_capability {
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u_long play_function;
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#define CDDOPLAYTRK 0x00000001
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/* Can play tracks/index */
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#define CDDOPLAYMSF 0x00000002
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/* Can play msf to msf */
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#define CDDOPLAYBLOCKS 0x00000004
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/* Can play range of blocks */
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#define CDDOPAUSE 0x00000100
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/* Output can be paused */
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#define CDDORESUME 0x00000200
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/* Output can be resumed */
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#define CDDORESET 0x00000400
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/* Drive can be completely reset */
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#define CDDOSTART 0x00000800
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/* Audio can be started */
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#define CDDOSTOP 0x00001000
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/* Audio can be stopped */
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#define CDDOPITCH 0x00002000
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/* Audio pitch can be changed */
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u_long routing_function;
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#define CDREADVOLUME 0x00000001
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/* Volume settings can be read */
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#define CDSETVOLUME 0x00000002
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/* Volume settings can be set */
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#define CDSETMONO 0x00000100
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/* Output can be set to mono */
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#define CDSETSTEREO 0x00000200
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/* Output can be set to stereo (def) */
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#define CDSETLEFT 0x00000400
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/* Output can be set to left only */
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#define CDSETRIGHT 0x00000800
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/* Output can be set to right only */
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#define CDSETMUTE 0x00001000
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/* Output can be muted */
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#define CDSETPATCH 0x00008000
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/* Direct routing control allowed */
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u_long special_function;
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#define CDDOEJECT 0x00000001
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/* The tray can be opened */
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#define CDDOCLOSE 0x00000002
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/* The tray can be closed */
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#define CDDOLOCK 0x00000004
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/* The tray can be locked */
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#define CDREADHEADER 0x00000100
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/* Can read Table of Contents */
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#define CDREADENTRIES 0x00000200
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/* Can read TOC Entries */
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#define CDREADSUBQ 0x00000200
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/* Can read Subchannel info */
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#define CDREADRW 0x00000400
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/* Can read subcodes R-W */
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#define CDHASDEBUG 0x00004000
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/* The tray has dynamic debugging */
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};
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.Ed
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.It Dv CDIOCPLAYTRACKS
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.Pq Li "struct ioc_play_track"
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Start audio playback given a track address and length. The structure
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is defined as follows:
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.Bd -literal -offset indent
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struct ioc_play_track
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{
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u_char start_track;
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u_char start_index;
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u_char end_track;
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u_char end_index;
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};
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.Ed
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.It Dv CDIOCPLAYBLOCKS
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.Pq Li "struct ioc_play_blocks"
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Start audio playback given a block address and length. The structure
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is defined as follows:
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.Bd -literal -offset indent
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struct ioc_play_blocks
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{
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int blk;
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int len;
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};
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.Ed
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.It Dv CDIOCPLAYMSF
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.Pq Li "struct ioc_play_msf"
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Start audio playback given a `minutes-seconds-frames' address and
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length. The structure is defined as follows:
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.Bd -literal -offset indent
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struct ioc_play_msf
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{
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u_char start_m;
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u_char start_s;
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u_char start_f;
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u_char end_m;
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u_char end_s;
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u_char end_f;
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};
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.Ed
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.It Dv CDIOCREADSUBCHANNEL
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.Pq Li "struct ioc_read_subchannel"
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Read information from the subchannel at the location specified by this
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structure:
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.Bd -literal -offset indent
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struct ioc_read_subchannel {
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u_char address_format;
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#define CD_LBA_FORMAT 1
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#define CD_MSF_FORMAT 2
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u_char data_format;
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#define CD_SUBQ_DATA 0
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#define CD_CURRENT_POSITION 1
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#define CD_MEDIA_CATALOG 2
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#define CD_TRACK_INFO 3
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u_char track;
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int data_len;
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struct cd_sub_channel_info *data;
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};
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.Ed
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.It Dv CDIOREADTOCHEADER
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.Pq Li "struct ioc_toc_header"
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Return summary information about the table of contents for the mounted
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.Tn CD-ROM .
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The information is returned into the following structure:
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.Bd -literal -offset indent
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struct ioc_toc_header {
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u_short len;
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u_char starting_track;
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u_char ending_track;
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};
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.Ed
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.It Dv CDIOREADTOCENTRYS
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.Pq Li "struct ioc_read_toc_entry"
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Return information from the table of contents entries mentioned. (Yes, this
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command name is misspelled.) The argument structure is defined as follows:
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.Bd -literal -offset indent
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struct ioc_read_toc_entry {
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u_char address_format;
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u_char starting_track;
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u_short data_len;
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struct cd_toc_entry *data;
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};
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.Ed
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The requested data is written into an area of size
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.Li data_len
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and pointed to by
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.Li data .
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.It Dv CDIOCSETPATCH
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.Pq Li "struct ioc_patch"
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Attach various audio channels to various output channels. The
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argument structure is defined thusly:
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.Bd -literal -offset indent
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struct ioc_patch {
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u_char patch[4];
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/* one for each channel */
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};
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.Ed
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.It Dv CDIOCGETVOL
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.It Dv CDIOCSETVOL
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.Pq Li "struct ioc_vol"
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Get (set) information about the volume settings of the output channels. The
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argument structure is as follows:
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.Bd -literal -offset indent
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struct ioc_vol
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{
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u_char vol[4];
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/* one for each channel */
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};
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.Ed
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.It Dv CDIOCSETMONO
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Patch all output channels to all source channels.
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.It Dv CDIOCSETSTEREO
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Patch left source channel to the left output channel and the right
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source channel to the right output channel.
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.It Dv CDIOCSETMUTE
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Mute output without changing the volume settings.
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.It Dv CDIOCSETLEFT
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.It Dv CDIOCSETRIGHT
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Attach both output channels to the left (right) source channel.
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.It Dv CDIOCSETDEBUG
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.It Dv CDIOCCLRDEBUG
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Turn on (off) debugging for the appropriate device.
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.It Dv CDIOCPAUSE
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.It Dv CDIOCRESUME
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Pause (resume) audio play, without resetting the location of the read-head.
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.It Dv CDIOCRESET
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Reset the drive.
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.It Dv CDIOCSTART
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.It Dv CDIOCSTOP
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Tell the drive to spin-up (-down) the
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.Tn CD-ROM .
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.It Dv CDIOCALLOW
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.It Dv CDIOCPREVENT
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Tell the drive to allow (prevent) manual ejection of the
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.Tn CD-ROM
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disc. Not all drives support this feature.
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.It Dv CDIOCEJECT
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Eject the
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.Tn CD-ROM .
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.It Dv CDIOCCLOSE
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Tell the drive to close its door and load the media. Not all drives
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support this feature.
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.It Dv CDIOCPITCH
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.Pq Li "struct ioc_pitch"
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For drives that support it, this command instructs the drive to play
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the audio at a faster or slower rate than normal. Values of
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.Li speed
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between -32767 and -1 result in slower playback; a zero value
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indicates normal speed; and values from 1 to 32767 give faster
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playback. Drives with less than 16 bits of resolution will silently
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ignore less-significant bits. The structure is defined thusly:
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.Bd -literal -offset indent
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struct ioc_pitch
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{
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short speed;
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};
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.Ed
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.El
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.Sh NOTES
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When a
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.Tn CD-ROM
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is changed in a drive controlled by the
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.Nm
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driver, then the act of changing the media will invalidate the
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disklabel and information held within the kernel. To stop corruption,
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all accesses to the device will be discarded until there are no more
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open file descriptors referencing the device. During this period, all
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new open attempts will be rejected. When no more open file descriptors
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reference the device, the first next open will load a new set of
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parameters (including disklabel) for the drive.
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.Pp
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The audio code in the
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.Nm
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driver only support
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.Tn SCSI-2
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standard audio commands. Because many
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.Tn CD-ROM
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manufacturers have not followed the standard, there are many
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.Tn CD-ROM
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drives for which audio will not work. Some work is planned to support
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some of the more common `broken'
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.Tn CD-ROM
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drives; however, this is not yet under way.
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.Sh CHANGER OPERATION
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This driver has built-in support for LUN-based CD changers. A LUN-based CD
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changer is a drive that can hold two or more CDs, but only has one CD
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player mechanism. Each CD in the drive shows up as a seperate logical unit
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on the
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.Tn SCSI
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bus. The
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.Nm cd
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driver automatically recognizes LUN-based changers, and routes commands for
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changers through an internal scheduler. The scheduler prevents changer
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"thrashing", which is caused by sending commands to different LUNs in the
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changer at the same time.
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.Pp
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The scheduler honors minimum and maximum time
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quanta that the driver will spend on a particular LUN. The minimum time
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is the guaranteed minimum amount of time that the driver will spend on a
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given LUN, even if there is no oustanding I/O for that LUN. The maximum
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time is the maximum amount of time the changer will spend on a LUN if there
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is oustdanding I/O for another LUN. If there is no outstanding I/O for
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another LUN, the driver will allow indefinite access to a given LUN.
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.Pp
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The minimum and maximum time quanta are configurable via kernel options and
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also via sysctl variables. The kernel options are:
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.Bl -tag -width 1234 -compact
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.It Cd options "CHANGER_MIN_BUSY_SECONDS=3"
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.It Cd options "CHANGER_MAX_BUSY_SECONDS=11"
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.El
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.Pp
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The sysctl variables are:
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.Pp
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.Bl -tag -width 1234 -compact
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.It Cd kern.cam.cd.changer.min_busy_seconds
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.It Cd kern.cam.cd.changer.max_busy_seconds
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.El
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.Pp
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It is suggested that the user try experimenting with the minimum and
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maximum timeouts via the sysctl variables to arrive at the proper values
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for your changer. Once you have settled on the proper timeouts for your
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changer, you can then put them in your kernel config file.
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.Pp
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If your system does have a LUN-based changer, you may notice that the
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probe messages for the various LUNs of the changer will continue to appear
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while the boot process is going on. This is normal, and is caused by the
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changer scheduling code.
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.Sh FILES
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.Bl -tag -width /dev/rcd[0-9][a-h] -compact
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.It Pa /dev/cd[0-9][a-h]
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block mode
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.Tn CD-ROM
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devices
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.It Pa /dev/rcd[0-9][a-h]
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raw mode
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.Tn CD-ROM
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devices
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.El
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.Sh DIAGNOSTICS
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None.
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.Sh SEE ALSO
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.Xr scsi 4 ,
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.Xr da 4 ,
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.Xr disklabel 5 ,
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.Xr disklabel 8 ,
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.Xr cd 9
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.Sh BUGS
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The names of the structures used for the third argument to
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.Fn ioctl
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were poorly chosen, and a number of spelling errors have survived in
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the names of the
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.Fn ioctl
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commands.
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.Pp
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There is no mechanism currently to set different minimum and maximum
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timeouts for different CD changers; the timeout values set by the kernel
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options or the sysctl variables apply to all LUN-based CD changers in the
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system. It is possible to implement such support, but the sysctl
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impelmentation at least would be rather inelegant, because of the current
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inability of the sysctl code to handle the addition of nodes after compile
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time. Thus, it would take one dynamically sized sysctl variable and a
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userland utility to get/set the timeout values. Implementation of separate
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timeouts for different CD devices in the kernel config file would likely
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require modification of
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.Xr config 8
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to support the two timeouts when hardwiring
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.Nm cd
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devices.
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.Sh HISTORY
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This
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.Nm cd
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driver is based upon the
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.Nm cd
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driver written by Julian Ellischer, which appeared in 386BSD 0.1. The
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CAM version of the
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.Nm cd
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driver was written by Kenneth Merry and first appeared in
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.Fx 3.0 .
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