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b8a8ed5664
This code was heavily broken few months ago during CAM locking changes. Fixing it would require almost complete rewrite. Since there are no known devices on market using this interface younger then ~15 years, and they are CD, not even DVD, I don't see much reason to rewrite it. This change does not mean those devices won't work. They will just work slower due to inefficient disks load/unload schedule if several LUNs accessed same time. Discussed with: ken@ Silence on: scsi@, hardware@ MFC after: 1 week
373 lines
9.6 KiB
Groff
373 lines
9.6 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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.\" $FreeBSD$
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.\"
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.Dd April 9, 2014
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.Dt CD 4
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.Os
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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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.Sh DESCRIPTION
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The
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.Nm
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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 ada 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.
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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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.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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.In sys/cdio.h
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and
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.In sys/disklabel.h .
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.Bl -tag -width CDIOCREADSUBCHANNEL
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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.
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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.
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This structure is defined in the header file
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.In sys/disklabel.h .
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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.
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The structure 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.
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The structure 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.
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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.
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.Pq Yes, this command name is misspelled.
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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.
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The 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.
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The 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.
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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.
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Not all drives support this feature.
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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.
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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.
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During this period, all
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new open attempts will be rejected.
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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.
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As 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.
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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 SYSCTL VARIABLES
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The following variables are available as both
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.Xr sysctl 8
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variables and
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.Xr loader 8
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tunables:
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.Bl -tag -width 12
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.It kern.cam.cd.retry_count
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.Pp
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This variable determines how many times the
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.Nm
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driver will retry a READ or WRITE command.
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This does not affect the number of retries used during probe time or for
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the
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.Nm
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driver dump routine.
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This value currently defaults to 4.
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.It kern.cam.cd.%d.minimum_cmd_size
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.Pp
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The
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.Nm
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driver attempts to automatically determine whether the drive it is talking
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to supports 6 byte or 10 byte MODE SENSE/MODE SELECT operations.
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Many
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.Tn SCSI
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drives only support 6 byte commands, and
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.Tn ATAPI
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drives only support 10 byte commands.
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The
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.Nm
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driver first attempts to determine whether the protocol in use typically
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supports 6 byte commands by issuing a CAM Path Inquiry CCB.
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It will then default to 6 byte or 10 byte commands as appropriate.
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After that, the
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.Nm
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driver defaults to using 6 byte commands (assuming the protocol the drive
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speaks claims to support 6 byte commands), until one fails with a
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.Tn SCSI
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ILLEGAL REQUEST error.
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Then it tries the 10 byte version of the command to
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see if that works instead.
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Users can change the default via per-drive
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sysctl variables and loader tunables.
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Where
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.Dq %d
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is the unit number of the drive in question.
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Valid minimum command sizes
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are 6 and 10.
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Any value above 6 will be rounded to 10, and any value below
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6 will be rounded to 6.
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.El
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.Sh FILES
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.Bl -tag -width /dev/cd[0-9][a-h] -compact
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.It Pa /dev/cd[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 cam 4 ,
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.Xr da 4 ,
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.Xr disklabel 8 ,
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.Xr cd 9
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.Sh HISTORY
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This
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.Nm
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driver is based upon the
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.Nm
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driver written by Julian Elischer, which appeared in
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.Bx 386 0.1 .
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The
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CAM version of the
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.Nm
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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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.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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