cb32189e23
out of cdregister() and daregister(), which are run from interrupt context. The sysctl code does blocking mallocs (M_WAITOK), which causes problems if malloc(9) actually needs to sleep. The eventual fix for this issue will involve moving the CAM probe process inside a kernel thread. For now, though, I have fixed the issue by moving dynamic sysctl variable creation for these two drivers to a task queue running in a kernel thread. The existing task queues (taskqueue_swi and taskqueue_swi_giant) run in software interrupt handlers, which wouldn't fix the problem at hand. So I have created a new task queue, taskqueue_thread, that runs inside a kernel thread. (It also runs outside of Giant -- clients must explicitly acquire and release Giant in their taskqueue functions.) scsi_cd.c: Remove sysctl variable creation code from cdregister(), and move it to a new function, cdsysctlinit(). Queue cdsysctlinit() to the taskqueue_thread taskqueue once we have fully registered the cd(4) driver instance. scsi_da.c: Remove sysctl variable creation code from daregister(), and move it to move it to a new function, dasysctlinit(). Queue dasysctlinit() to the taskqueue_thread taskqueue once we have fully registered the da(4) instance. taskqueue.h: Declare the new taskqueue_thread taskqueue, update some comments. subr_taskqueue.c: Create the new kernel thread taskqueue. This taskqueue runs outside of Giant, so any functions queued to it would need to explicitly acquire/release Giant if they need it. cd.4: Update the cd(4) man page to talk about the minimum command size sysctl/loader tunable. Also note that the changer variables are available as loader tunables as well. da.4: Update the da(4) man page to cover the retry_count, default_timeout and minimum_cmd_size sysctl variables/loader tunables. Remove references to /dev/r???, they aren't used any longer. cd.9: Update the cd(9) man page to describe the CD_Q_10_BYTE_ONLY quirk. taskqueue.9: Update the taskqueue(9) man page to describe the new thread task queue, and the taskqueue_swi_giant queue. MFC after: 3 days
515 lines
14 KiB
Groff
515 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
|
|
.\" 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 September 2, 2003
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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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.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
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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 ad 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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.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
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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
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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.
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The 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.
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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
|
|
.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.
|
|
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.
|
|
.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
|
|
indicates normal speed; and values from 1 to 32767 give faster
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playback.
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|
Drives with less than 16 bits of resolution will silently
|
|
ignore less-significant bits.
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|
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,
|
|
all accesses to the device will be discarded until there are no more
|
|
open file descriptors referencing the device.
|
|
During this period, all
|
|
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
|
|
parameters (including disklabel) for the drive.
|
|
.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.
|
|
As many
|
|
.Tn CD-ROM
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|
manufacturers have not followed the standard, there are many
|
|
.Tn CD-ROM
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|
drives for which audio will not work.
|
|
Some work is planned to support
|
|
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.
|
|
.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. Many
|
|
.Tn SCSI
|
|
drives only support 6 byte commands, and
|
|
.Tn ATAPI
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|
drives only support 10 byte commands.
|
|
The
|
|
.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.
|
|
It will then default to 6 byte or 10 byte commands as appropriate.
|
|
After that, the
|
|
.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
|
|
.Tn SCSI
|
|
ILLEGAL REQUEST error. Then it tries the 10 byte version of the command to
|
|
see if that works instead. Users can change the default via per-drive
|
|
sysctl variables and loader tunables. The variable names are the same in
|
|
both instances:
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|
.Pp
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|
.Va kern.cam.cd.%d.minimum_cmd_size
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|
.Pp
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|
Where
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|
.Dq %d
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|
is the unit number of the drive in question. Valid minimum command sizes
|
|
are 6 and 10. 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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.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 separate logical unit
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|
on the
|
|
.Tn SCSI
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|
bus.
|
|
The
|
|
.Nm
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|
driver automatically recognizes LUN-based changers, and routes commands for
|
|
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
|
|
changer at the same time.
|
|
.Pp
|
|
The scheduler honors minimum and maximum time
|
|
quanta that the driver will spend on a particular LUN.
|
|
The minimum time
|
|
is the guaranteed minimum amount of time that the driver will spend on a
|
|
given LUN, even if there is no outstanding I/O for that LUN.
|
|
The maximum
|
|
time is the maximum amount of time the changer will spend on a LUN if there
|
|
is outstanding I/O for another LUN.
|
|
If there is no outstanding I/O for
|
|
another LUN, the driver will allow indefinite access to a given LUN.
|
|
.Pp
|
|
The minimum and maximum time quanta are configurable via kernel options and
|
|
also via sysctl and kernel tunable variables.
|
|
The kernel options are:
|
|
.Pp
|
|
.Bl -item -compact
|
|
.It
|
|
.Cd "options ""CHANGER_MIN_BUSY_SECONDS=3"""
|
|
.It
|
|
.Cd "options ""CHANGER_MAX_BUSY_SECONDS=11"""
|
|
.El
|
|
.Pp
|
|
The sysctl/kernel tunable variables are:
|
|
.Pp
|
|
.Bl -item -compact
|
|
.It
|
|
.Va kern.cam.cd.changer.min_busy_seconds
|
|
.It
|
|
.Va kern.cam.cd.changer.max_busy_seconds
|
|
.El
|
|
.Pp
|
|
It is suggested that the user try experimenting with the minimum and
|
|
maximum timeouts via the sysctl variables to arrive at the proper values
|
|
for your changer.
|
|
Once you have settled on the proper timeouts for your
|
|
changer, you can then put them in your kernel config file.
|
|
.Pp
|
|
If your system does have a LUN-based changer, you may notice that the
|
|
probe messages for the various LUNs of the changer will continue to appear
|
|
while the boot process is going on.
|
|
This is normal, and is caused by the
|
|
changer scheduling code.
|
|
.Sh FILES
|
|
.Bl -tag -width /dev/cd[0-9][a-h] -compact
|
|
.It Pa /dev/cd[0-9][a-h]
|
|
raw mode
|
|
.Tn CD-ROM
|
|
devices
|
|
.El
|
|
.Sh DIAGNOSTICS
|
|
None.
|
|
.Sh SEE ALSO
|
|
.Xr da 4 ,
|
|
.Xr scsi 4 ,
|
|
.Xr disklabel 5 ,
|
|
.Xr disklabel 8 ,
|
|
.Xr cd 9
|
|
.Sh BUGS
|
|
The names of the structures used for the third argument to
|
|
.Fn ioctl
|
|
were poorly chosen, and a number of spelling errors have survived in
|
|
the names of the
|
|
.Fn ioctl
|
|
commands.
|
|
.Pp
|
|
There is no mechanism currently to set different minimum and maximum
|
|
timeouts for different CD changers; the timeout values set by the kernel
|
|
options or the sysctl variables apply to all LUN-based CD changers in the
|
|
system.
|
|
It is possible to implement such support, but the sysctl
|
|
implementation at least would be rather inelegant, because of the current
|
|
inability of the sysctl code to handle the addition of nodes after compile
|
|
time.
|
|
Thus, it would take one dynamically sized sysctl variable and a
|
|
userland utility to get/set the timeout values.
|
|
Implementation of separate
|
|
timeouts for different CD devices in the kernel config file would likely
|
|
require modification of
|
|
.Xr config 8
|
|
to support the two timeouts when hardwiring
|
|
.Nm
|
|
devices.
|
|
.Sh HISTORY
|
|
This
|
|
.Nm
|
|
driver is based upon the
|
|
.Nm
|
|
driver written by Julian Elischer, which appeared in
|
|
.Bx 386 0.1 .
|
|
The
|
|
CAM version of the
|
|
.Nm
|
|
driver was written by Kenneth Merry and first appeared in
|
|
.Fx 3.0 .
|