1.\" Copyright (c) 1996 2.\" Julian Elischer <julian@FreeBSD.org>. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 10.\" 2. Redistributions in binary form must reproduce the above copyright 11.\" notice, this list of conditions and the following disclaimer in the 12.\" documentation and/or other materials provided with the distribution. 13.\" 14.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24.\" SUCH DAMAGE. 25.\" 26.\" $FreeBSD$ 27.\" 28.Dd January 8, 2009 29.Dt CD 4 30.Os 31.Sh NAME 32.Nm cd 33.Nd SCSI CD-ROM driver 34.Sh SYNOPSIS 35.Cd device cd 36.Cd "options ""CHANGER_MIN_BUSY_SECONDS=3""" 37.Cd "options ""CHANGER_MAX_BUSY_SECONDS=11"" 38.Sh DESCRIPTION 39The 40.Nm 41driver provides support for a 42.Tn SCSI 43.Tn CD-ROM 44(Compact Disc-Read Only Memory) drive. 45In an attempt to look like a regular disk, the 46.Nm 47driver synthesizes a partition table, with one partition covering the entire 48.Tn CD-ROM . 49It is possible to modify this partition table using 50.Xr disklabel 8 , 51but it will only last until the 52.Tn CD-ROM 53is unmounted. 54In general the interfaces are similar to those described by 55.Xr ad 4 56and 57.Xr da 4 . 58.Pp 59As the 60.Tn SCSI 61adapter is probed during boot, the 62.Tn SCSI 63bus is scanned for devices. 64Any devices found which answer as CDROM 65(type 5) or WORM (type 4) type devices will be `attached' to the 66.Nm 67driver. 68Prior to 69.Fx 2.1 , 70the first device found will be attached as 71.Li cd0 72the next, 73.Li cd1 , 74etc. 75Beginning in 76.Fx 2.1 77it is possible to specify what cd unit a device should 78come on line as; refer to 79.Xr scsi 4 80for details on kernel configuration. 81.Pp 82The system utility 83.Xr disklabel 8 84may be used to read the synthesized 85disk label 86structure, which will contain correct figures for the size of the 87.Tn CD-ROM 88should that information be required. 89.Sh KERNEL CONFIGURATION 90Any number of 91.Tn CD-ROM 92devices may be attached to the system regardless of system 93configuration as all resources are dynamically allocated. 94.Sh IOCTLS 95The following 96.Xr ioctl 2 97calls which apply to 98.Tn SCSI 99.Tn CD-ROM 100drives are defined 101in the header files 102.In sys/cdio.h 103and 104.In sys/disklabel.h . 105.Pp 106.Bl -tag -width CDIOCREADSUBCHANNEL 107.It Dv DIOCGDINFO 108.It Dv DIOCSDINFO 109.Pq Li "struct disklabel" 110Read or write the in-core copy of the disklabel for the 111drive. 112The disklabel is initialized with information 113read from the scsi inquiry commands, and should be the same as 114the information printed at boot. 115This structure is defined in 116.Xr disklabel 5 . 117.It Dv CDIOCCAPABILITY 118.Pq Li "struct ioc_capability" 119Retrieve information from the drive on what features it supports. 120The information is returned in the following structure: 121.Bd -literal -offset indent 122struct ioc_capability { 123 u_long play_function; 124#define CDDOPLAYTRK 0x00000001 125 /* Can play tracks/index */ 126#define CDDOPLAYMSF 0x00000002 127 /* Can play msf to msf */ 128#define CDDOPLAYBLOCKS 0x00000004 129 /* Can play range of blocks */ 130#define CDDOPAUSE 0x00000100 131 /* Output can be paused */ 132#define CDDORESUME 0x00000200 133 /* Output can be resumed */ 134#define CDDORESET 0x00000400 135 /* Drive can be completely reset */ 136#define CDDOSTART 0x00000800 137 /* Audio can be started */ 138#define CDDOSTOP 0x00001000 139 /* Audio can be stopped */ 140#define CDDOPITCH 0x00002000 141 /* Audio pitch can be changed */ 142 143 u_long routing_function; 144#define CDREADVOLUME 0x00000001 145 /* Volume settings can be read */ 146#define CDSETVOLUME 0x00000002 147 /* Volume settings can be set */ 148#define CDSETMONO 0x00000100 149 /* Output can be set to mono */ 150#define CDSETSTEREO 0x00000200 151 /* Output can be set to stereo (def) */ 152#define CDSETLEFT 0x00000400 153 /* Output can be set to left only */ 154#define CDSETRIGHT 0x00000800 155 /* Output can be set to right only */ 156#define CDSETMUTE 0x00001000 157 /* Output can be muted */ 158#define CDSETPATCH 0x00008000 159 /* Direct routing control allowed */ 160 161 u_long special_function; 162#define CDDOEJECT 0x00000001 163 /* The tray can be opened */ 164#define CDDOCLOSE 0x00000002 165 /* The tray can be closed */ 166#define CDDOLOCK 0x00000004 167 /* The tray can be locked */ 168#define CDREADHEADER 0x00000100 169 /* Can read Table of Contents */ 170#define CDREADENTRIES 0x00000200 171 /* Can read TOC Entries */ 172#define CDREADSUBQ 0x00000200 173 /* Can read Subchannel info */ 174#define CDREADRW 0x00000400 175 /* Can read subcodes R-W */ 176#define CDHASDEBUG 0x00004000 177 /* The tray has dynamic debugging */ 178}; 179.Ed 180.It Dv CDIOCPLAYTRACKS 181.Pq Li "struct ioc_play_track" 182Start audio playback given a track address and length. 183The structure is defined as follows: 184.Bd -literal -offset indent 185struct ioc_play_track 186{ 187 u_char start_track; 188 u_char start_index; 189 u_char end_track; 190 u_char end_index; 191}; 192.Ed 193.It Dv CDIOCPLAYBLOCKS 194.Pq Li "struct ioc_play_blocks" 195Start audio playback given a block address and length. 196The structure is defined as follows: 197.Bd -literal -offset indent 198struct ioc_play_blocks 199{ 200 int blk; 201 int len; 202}; 203.Ed 204.It Dv CDIOCPLAYMSF 205.Pq Li "struct ioc_play_msf" 206Start audio playback given a `minutes-seconds-frames' address and 207length. 208The structure is defined as follows: 209.Bd -literal -offset indent 210struct ioc_play_msf 211{ 212 u_char start_m; 213 u_char start_s; 214 u_char start_f; 215 u_char end_m; 216 u_char end_s; 217 u_char end_f; 218}; 219.Ed 220.It Dv CDIOCREADSUBCHANNEL 221.Pq Li "struct ioc_read_subchannel" 222Read information from the subchannel at the location specified by this 223structure: 224.Bd -literal -offset indent 225struct ioc_read_subchannel { 226 u_char address_format; 227#define CD_LBA_FORMAT 1 228#define CD_MSF_FORMAT 2 229 u_char data_format; 230#define CD_SUBQ_DATA 0 231#define CD_CURRENT_POSITION 1 232#define CD_MEDIA_CATALOG 2 233#define CD_TRACK_INFO 3 234 u_char track; 235 int data_len; 236 struct cd_sub_channel_info *data; 237}; 238.Ed 239.It Dv CDIOREADTOCHEADER 240.Pq Li "struct ioc_toc_header" 241Return summary information about the table of contents for the mounted 242.Tn CD-ROM . 243The information is returned into the following structure: 244.Bd -literal -offset indent 245struct ioc_toc_header { 246 u_short len; 247 u_char starting_track; 248 u_char ending_track; 249}; 250.Ed 251.It Dv CDIOREADTOCENTRYS 252.Pq Li "struct ioc_read_toc_entry" 253Return information from the table of contents entries mentioned. 254.Pq Yes, this command name is misspelled. 255The argument structure is defined as follows: 256.Bd -literal -offset indent 257struct ioc_read_toc_entry { 258 u_char address_format; 259 u_char starting_track; 260 u_short data_len; 261 struct cd_toc_entry *data; 262}; 263.Ed 264The requested data is written into an area of size 265.Li data_len 266and pointed to by 267.Li data . 268.It Dv CDIOCSETPATCH 269.Pq Li "struct ioc_patch" 270Attach various audio channels to various output channels. 271The argument structure is defined thusly: 272.Bd -literal -offset indent 273struct ioc_patch { 274 u_char patch[4]; 275 /* one for each channel */ 276}; 277.Ed 278.It Dv CDIOCGETVOL 279.It Dv CDIOCSETVOL 280.Pq Li "struct ioc_vol" 281Get (set) information about the volume settings of the output channels. 282The argument structure is as follows: 283.Bd -literal -offset indent 284struct ioc_vol 285{ 286 u_char vol[4]; 287 /* one for each channel */ 288}; 289.Ed 290.It Dv CDIOCSETMONO 291Patch all output channels to all source channels. 292.It Dv CDIOCSETSTEREO 293Patch left source channel to the left output channel and the right 294source channel to the right output channel. 295.It Dv CDIOCSETMUTE 296Mute output without changing the volume settings. 297.It Dv CDIOCSETLEFT 298.It Dv CDIOCSETRIGHT 299Attach both output channels to the left (right) source channel. 300.It Dv CDIOCSETDEBUG 301.It Dv CDIOCCLRDEBUG 302Turn on (off) debugging for the appropriate device. 303.It Dv CDIOCPAUSE 304.It Dv CDIOCRESUME 305Pause (resume) audio play, without resetting the location of the read-head. 306.It Dv CDIOCRESET 307Reset the drive. 308.It Dv CDIOCSTART 309.It Dv CDIOCSTOP 310Tell the drive to spin-up (-down) the 311.Tn CD-ROM . 312.It Dv CDIOCALLOW 313.It Dv CDIOCPREVENT 314Tell the drive to allow (prevent) manual ejection of the 315.Tn CD-ROM 316disc. 317Not all drives support this feature. 318.It Dv CDIOCEJECT 319Eject the 320.Tn CD-ROM . 321.It Dv CDIOCCLOSE 322Tell the drive to close its door and load the media. 323Not all drives support this feature. 324.It Dv CDIOCPITCH 325.Pq Li "struct ioc_pitch" 326For drives that support it, this command instructs the drive to play 327the audio at a faster or slower rate than normal. 328Values of 329.Li speed 330between -32767 and -1 result in slower playback; a zero value 331indicates normal speed; and values from 1 to 32767 give faster 332playback. 333Drives with less than 16 bits of resolution will silently 334ignore less-significant bits. 335The structure is defined thusly: 336.Bd -literal -offset indent 337struct ioc_pitch 338{ 339 short speed; 340}; 341.Ed 342.El 343.Sh NOTES 344When a 345.Tn CD-ROM 346is changed in a drive controlled by the 347.Nm 348driver, then the act of changing the media will invalidate the 349disklabel and information held within the kernel. 350To stop corruption, 351all accesses to the device will be discarded until there are no more 352open file descriptors referencing the device. 353During this period, all 354new open attempts will be rejected. 355When no more open file descriptors 356reference the device, the first next open will load a new set of 357parameters (including disklabel) for the drive. 358.Pp 359The audio code in the 360.Nm 361driver only support 362.Tn SCSI-2 363standard audio commands. 364As many 365.Tn CD-ROM 366manufacturers have not followed the standard, there are many 367.Tn CD-ROM 368drives for which audio will not work. 369Some work is planned to support 370some of the more common `broken' 371.Tn CD-ROM 372drives; however, this is not yet under way. 373.Sh CHANGER OPERATION 374This driver has built-in support for LUN-based CD changers. 375A LUN-based CD 376changer is a drive that can hold two or more CDs, but only has one CD 377player mechanism. 378Each CD in the drive shows up as a separate logical unit 379on the 380.Tn SCSI 381bus. 382The 383.Nm 384driver automatically recognizes LUN-based changers, and routes commands for 385changers through an internal scheduler. 386The scheduler prevents changer 387"thrashing", which is caused by sending commands to different LUNs in the 388changer at the same time. 389.Pp 390The scheduler honors minimum and maximum time 391quanta that the driver will spend on a particular LUN. 392The minimum time 393is the guaranteed minimum amount of time that the driver will spend on a 394given LUN, even if there is no outstanding I/O for that LUN. 395The maximum 396time is the maximum amount of time the changer will spend on a LUN if there 397is outstanding I/O for another LUN. 398If there is no outstanding I/O for 399another LUN, the driver will allow indefinite access to a given LUN. 400.Pp 401The minimum and maximum time quanta are configurable via kernel options and 402also via sysctl and kernel tunable variables. 403The kernel options are: 404.Pp 405.Bl -item -compact 406.It 407.Cd "options ""CHANGER_MIN_BUSY_SECONDS=3""" 408.It 409.Cd "options ""CHANGER_MAX_BUSY_SECONDS=11""" 410.El 411.Pp 412The sysctl/kernel tunable variables are: 413.Pp 414.Bl -item -compact 415.It 416.Va kern.cam.cd.changer.min_busy_seconds 417.It 418.Va kern.cam.cd.changer.max_busy_seconds 419.El 420.Pp 421It is suggested that the user try experimenting with the minimum and 422maximum timeouts via the sysctl variables to arrive at the proper values 423for your changer. 424Once you have settled on the proper timeouts for your 425changer, you can then put them in your kernel config file. 426.Pp 427If your system does have a LUN-based changer, you may notice that the 428probe messages for the various LUNs of the changer will continue to appear 429while the boot process is going on. 430This is normal, and is caused by the 431changer scheduling code. 432.Sh SYSCTL VARIABLES 433The following variables are available as both 434.Xr sysctl 8 435variables and 436.Xr loader 8 437tunables: 438.Bl -tag -width 12 439.It kern.cam.cd.retry_count 440.Pp 441This variable determines how many times the 442.Nm 443driver will retry a READ or WRITE command. 444This does not affect the number of retries used during probe time or for 445the 446.Nm 447driver dump routine. 448This value currently defaults to 4. 449.It kern.cam.cd.%d.minimum_cmd_size 450.Pp 451The 452.Nm 453driver attempts to automatically determine whether the drive it is talking 454to supports 6 byte or 10 byte MODE SENSE/MODE SELECT operations. 455Many 456.Tn SCSI 457drives only support 6 byte commands, and 458.Tn ATAPI 459drives only support 10 byte commands. 460The 461.Nm 462driver first attempts to determine whether the protocol in use typically 463supports 6 byte commands by issuing a CAM Path Inquiry CCB. 464It will then default to 6 byte or 10 byte commands as appropriate. 465After that, the 466.Nm 467driver defaults to using 6 byte commands (assuming the protocol the drive 468speaks claims to support 6 byte commands), until one fails with a 469.Tn SCSI 470ILLEGAL REQUEST error. 471Then it tries the 10 byte version of the command to 472see if that works instead. 473Users can change the default via per-drive 474sysctl variables and loader tunables. 475Where 476.Dq %d 477is the unit number of the drive in question. 478Valid minimum command sizes 479are 6 and 10. 480Any value above 6 will be rounded to 10, and any value below 4816 will be rounded to 6. 482.It kern.cam.cd.changer.min_busy_seconds 483.It kern.cam.cd.changer.max_busy_seconds 484.Pp 485Tune how long individual LUNs are 'locked' for I/O operations to 486optimize changer operation. 487See CHANGER OPERATION section for information on how to use these items. 488.El 489.Sh FILES 490.Bl -tag -width /dev/cd[0-9][a-h] -compact 491.It Pa /dev/cd[0-9][a-h] 492raw mode 493.Tn CD-ROM 494devices 495.El 496.Sh DIAGNOSTICS 497None. 498.Sh SEE ALSO 499.Xr cam 4 , 500.Xr da 4 , 501.Xr disklabel 5 , 502.Xr disklabel 8 , 503.Xr cd 9 504.Sh HISTORY 505This 506.Nm 507driver is based upon the 508.Nm 509driver written by Julian Elischer, which appeared in 510.Bx 386 0.1 . 511The 512CAM version of the 513.Nm 514driver was written by Kenneth Merry and first appeared in 515.Fx 3.0 . 516.Sh BUGS 517The names of the structures used for the third argument to 518.Fn ioctl 519were poorly chosen, and a number of spelling errors have survived in 520the names of the 521.Fn ioctl 522commands. 523.Pp 524There is no mechanism currently to set different minimum and maximum 525timeouts for different CD changers; the timeout values set by the kernel 526options or the sysctl variables apply to all LUN-based CD changers in the 527system. 528It is possible to implement such support, but the sysctl 529implementation at least would be rather inelegant, because of the current 530inability of the sysctl code to handle the addition of nodes after compile 531time. 532Thus, it would take one dynamically sized sysctl variable and a 533userland utility to get/set the timeout values. 534Implementation of separate 535timeouts for different CD devices in the kernel config file would likely 536require modification of 537.Xr config 8 538to support the two timeouts when hardwiring 539.Nm 540devices. 541