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.Bl -tag -width CDIOCREADSUBCHANNEL 106.It Dv DIOCGDINFO 107.It Dv DIOCSDINFO 108.Pq Li "struct disklabel" 109Read or write the in-core copy of the disklabel for the 110drive. 111The disklabel is initialized with information 112read from the scsi inquiry commands, and should be the same as 113the information printed at boot. 114This structure is defined in 115.Xr disklabel 5 . 116.It Dv CDIOCCAPABILITY 117.Pq Li "struct ioc_capability" 118Retrieve information from the drive on what features it supports. 119The information is returned in the following structure: 120.Bd -literal -offset indent 121struct ioc_capability { 122 u_long play_function; 123#define CDDOPLAYTRK 0x00000001 124 /* Can play tracks/index */ 125#define CDDOPLAYMSF 0x00000002 126 /* Can play msf to msf */ 127#define CDDOPLAYBLOCKS 0x00000004 128 /* Can play range of blocks */ 129#define CDDOPAUSE 0x00000100 130 /* Output can be paused */ 131#define CDDORESUME 0x00000200 132 /* Output can be resumed */ 133#define CDDORESET 0x00000400 134 /* Drive can be completely reset */ 135#define CDDOSTART 0x00000800 136 /* Audio can be started */ 137#define CDDOSTOP 0x00001000 138 /* Audio can be stopped */ 139#define CDDOPITCH 0x00002000 140 /* Audio pitch can be changed */ 141 142 u_long routing_function; 143#define CDREADVOLUME 0x00000001 144 /* Volume settings can be read */ 145#define CDSETVOLUME 0x00000002 146 /* Volume settings can be set */ 147#define CDSETMONO 0x00000100 148 /* Output can be set to mono */ 149#define CDSETSTEREO 0x00000200 150 /* Output can be set to stereo (def) */ 151#define CDSETLEFT 0x00000400 152 /* Output can be set to left only */ 153#define CDSETRIGHT 0x00000800 154 /* Output can be set to right only */ 155#define CDSETMUTE 0x00001000 156 /* Output can be muted */ 157#define CDSETPATCH 0x00008000 158 /* Direct routing control allowed */ 159 160 u_long special_function; 161#define CDDOEJECT 0x00000001 162 /* The tray can be opened */ 163#define CDDOCLOSE 0x00000002 164 /* The tray can be closed */ 165#define CDDOLOCK 0x00000004 166 /* The tray can be locked */ 167#define CDREADHEADER 0x00000100 168 /* Can read Table of Contents */ 169#define CDREADENTRIES 0x00000200 170 /* Can read TOC Entries */ 171#define CDREADSUBQ 0x00000200 172 /* Can read Subchannel info */ 173#define CDREADRW 0x00000400 174 /* Can read subcodes R-W */ 175#define CDHASDEBUG 0x00004000 176 /* The tray has dynamic debugging */ 177}; 178.Ed 179.It Dv CDIOCPLAYTRACKS 180.Pq Li "struct ioc_play_track" 181Start audio playback given a track address and length. 182The structure is defined as follows: 183.Bd -literal -offset indent 184struct ioc_play_track 185{ 186 u_char start_track; 187 u_char start_index; 188 u_char end_track; 189 u_char end_index; 190}; 191.Ed 192.It Dv CDIOCPLAYBLOCKS 193.Pq Li "struct ioc_play_blocks" 194Start audio playback given a block address and length. 195The structure is defined as follows: 196.Bd -literal -offset indent 197struct ioc_play_blocks 198{ 199 int blk; 200 int len; 201}; 202.Ed 203.It Dv CDIOCPLAYMSF 204.Pq Li "struct ioc_play_msf" 205Start audio playback given a `minutes-seconds-frames' address and 206length. 207The structure is defined as follows: 208.Bd -literal -offset indent 209struct ioc_play_msf 210{ 211 u_char start_m; 212 u_char start_s; 213 u_char start_f; 214 u_char end_m; 215 u_char end_s; 216 u_char end_f; 217}; 218.Ed 219.It Dv CDIOCREADSUBCHANNEL 220.Pq Li "struct ioc_read_subchannel" 221Read information from the subchannel at the location specified by this 222structure: 223.Bd -literal -offset indent 224struct ioc_read_subchannel { 225 u_char address_format; 226#define CD_LBA_FORMAT 1 227#define CD_MSF_FORMAT 2 228 u_char data_format; 229#define CD_SUBQ_DATA 0 230#define CD_CURRENT_POSITION 1 231#define CD_MEDIA_CATALOG 2 232#define CD_TRACK_INFO 3 233 u_char track; 234 int data_len; 235 struct cd_sub_channel_info *data; 236}; 237.Ed 238.It Dv CDIOREADTOCHEADER 239.Pq Li "struct ioc_toc_header" 240Return summary information about the table of contents for the mounted 241.Tn CD-ROM . 242The information is returned into the following structure: 243.Bd -literal -offset indent 244struct ioc_toc_header { 245 u_short len; 246 u_char starting_track; 247 u_char ending_track; 248}; 249.Ed 250.It Dv CDIOREADTOCENTRYS 251.Pq Li "struct ioc_read_toc_entry" 252Return information from the table of contents entries mentioned. 253.Pq Yes, this command name is misspelled. 254The argument structure is defined as follows: 255.Bd -literal -offset indent 256struct ioc_read_toc_entry { 257 u_char address_format; 258 u_char starting_track; 259 u_short data_len; 260 struct cd_toc_entry *data; 261}; 262.Ed 263The requested data is written into an area of size 264.Li data_len 265and pointed to by 266.Li data . 267.It Dv CDIOCSETPATCH 268.Pq Li "struct ioc_patch" 269Attach various audio channels to various output channels. 270The argument structure is defined thusly: 271.Bd -literal -offset indent 272struct ioc_patch { 273 u_char patch[4]; 274 /* one for each channel */ 275}; 276.Ed 277.It Dv CDIOCGETVOL 278.It Dv CDIOCSETVOL 279.Pq Li "struct ioc_vol" 280Get (set) information about the volume settings of the output channels. 281The argument structure is as follows: 282.Bd -literal -offset indent 283struct ioc_vol 284{ 285 u_char vol[4]; 286 /* one for each channel */ 287}; 288.Ed 289.It Dv CDIOCSETMONO 290Patch all output channels to all source channels. 291.It Dv CDIOCSETSTEREO 292Patch left source channel to the left output channel and the right 293source channel to the right output channel. 294.It Dv CDIOCSETMUTE 295Mute output without changing the volume settings. 296.It Dv CDIOCSETLEFT 297.It Dv CDIOCSETRIGHT 298Attach both output channels to the left (right) source channel. 299.It Dv CDIOCSETDEBUG 300.It Dv CDIOCCLRDEBUG 301Turn on (off) debugging for the appropriate device. 302.It Dv CDIOCPAUSE 303.It Dv CDIOCRESUME 304Pause (resume) audio play, without resetting the location of the read-head. 305.It Dv CDIOCRESET 306Reset the drive. 307.It Dv CDIOCSTART 308.It Dv CDIOCSTOP 309Tell the drive to spin-up (-down) the 310.Tn CD-ROM . 311.It Dv CDIOCALLOW 312.It Dv CDIOCPREVENT 313Tell the drive to allow (prevent) manual ejection of the 314.Tn CD-ROM 315disc. 316Not all drives support this feature. 317.It Dv CDIOCEJECT 318Eject the 319.Tn CD-ROM . 320.It Dv CDIOCCLOSE 321Tell the drive to close its door and load the media. 322Not all drives support this feature. 323.It Dv CDIOCPITCH 324.Pq Li "struct ioc_pitch" 325For drives that support it, this command instructs the drive to play 326the audio at a faster or slower rate than normal. 327Values of 328.Li speed 329between -32767 and -1 result in slower playback; a zero value 330indicates normal speed; and values from 1 to 32767 give faster 331playback. 332Drives with less than 16 bits of resolution will silently 333ignore less-significant bits. 334The structure is defined thusly: 335.Bd -literal -offset indent 336struct ioc_pitch 337{ 338 short speed; 339}; 340.Ed 341.El 342.Sh NOTES 343When a 344.Tn CD-ROM 345is changed in a drive controlled by the 346.Nm 347driver, then the act of changing the media will invalidate the 348disklabel and information held within the kernel. 349To stop corruption, 350all accesses to the device will be discarded until there are no more 351open file descriptors referencing the device. 352During this period, all 353new open attempts will be rejected. 354When no more open file descriptors 355reference the device, the first next open will load a new set of 356parameters (including disklabel) for the drive. 357.Pp 358The audio code in the 359.Nm 360driver only support 361.Tn SCSI-2 362standard audio commands. 363As many 364.Tn CD-ROM 365manufacturers have not followed the standard, there are many 366.Tn CD-ROM 367drives for which audio will not work. 368Some work is planned to support 369some of the more common `broken' 370.Tn CD-ROM 371drives; however, this is not yet under way. 372.Sh CHANGER OPERATION 373This driver has built-in support for LUN-based CD changers. 374A LUN-based CD 375changer is a drive that can hold two or more CDs, but only has one CD 376player mechanism. 377Each CD in the drive shows up as a separate logical unit 378on the 379.Tn SCSI 380bus. 381The 382.Nm 383driver automatically recognizes LUN-based changers, and routes commands for 384changers through an internal scheduler. 385The scheduler prevents changer 386"thrashing", which is caused by sending commands to different LUNs in the 387changer at the same time. 388.Pp 389The scheduler honors minimum and maximum time 390quanta that the driver will spend on a particular LUN. 391The minimum time 392is the guaranteed minimum amount of time that the driver will spend on a 393given LUN, even if there is no outstanding I/O for that LUN. 394The maximum 395time is the maximum amount of time the changer will spend on a LUN if there 396is outstanding I/O for another LUN. 397If there is no outstanding I/O for 398another LUN, the driver will allow indefinite access to a given LUN. 399.Pp 400The minimum and maximum time quanta are configurable via kernel options and 401also via sysctl and kernel tunable variables. 402The kernel options are: 403.Pp 404.Bl -item -compact 405.It 406.Cd "options ""CHANGER_MIN_BUSY_SECONDS=3""" 407.It 408.Cd "options ""CHANGER_MAX_BUSY_SECONDS=11""" 409.El 410.Pp 411The sysctl/kernel tunable variables are: 412.Pp 413.Bl -item -compact 414.It 415.Va kern.cam.cd.changer.min_busy_seconds 416.It 417.Va kern.cam.cd.changer.max_busy_seconds 418.El 419.Pp 420It is suggested that the user try experimenting with the minimum and 421maximum timeouts via the sysctl variables to arrive at the proper values 422for your changer. 423Once you have settled on the proper timeouts for your 424changer, you can then put them in your kernel config file. 425.Pp 426If your system does have a LUN-based changer, you may notice that the 427probe messages for the various LUNs of the changer will continue to appear 428while the boot process is going on. 429This is normal, and is caused by the 430changer scheduling code. 431.Sh SYSCTL VARIABLES 432The following variables are available as both 433.Xr sysctl 8 434variables and 435.Xr loader 8 436tunables: 437.Bl -tag -width 12 438.It kern.cam.cd.retry_count 439.Pp 440This variable determines how many times the 441.Nm 442driver will retry a READ or WRITE command. 443This does not affect the number of retries used during probe time or for 444the 445.Nm 446driver dump routine. 447This value currently defaults to 4. 448.It kern.cam.cd.%d.minimum_cmd_size 449.Pp 450The 451.Nm 452driver attempts to automatically determine whether the drive it is talking 453to supports 6 byte or 10 byte MODE SENSE/MODE SELECT operations. 454Many 455.Tn SCSI 456drives only support 6 byte commands, and 457.Tn ATAPI 458drives only support 10 byte commands. 459The 460.Nm 461driver first attempts to determine whether the protocol in use typically 462supports 6 byte commands by issuing a CAM Path Inquiry CCB. 463It will then default to 6 byte or 10 byte commands as appropriate. 464After that, the 465.Nm 466driver defaults to using 6 byte commands (assuming the protocol the drive 467speaks claims to support 6 byte commands), until one fails with a 468.Tn SCSI 469ILLEGAL REQUEST error. 470Then it tries the 10 byte version of the command to 471see if that works instead. 472Users can change the default via per-drive 473sysctl variables and loader tunables. 474Where 475.Dq %d 476is the unit number of the drive in question. 477Valid minimum command sizes 478are 6 and 10. 479Any value above 6 will be rounded to 10, and any value below 4806 will be rounded to 6. 481.It kern.cam.cd.changer.min_busy_seconds 482.It kern.cam.cd.changer.max_busy_seconds 483.Pp 484Tune how long individual LUNs are 'locked' for I/O operations to 485optimize changer operation. 486See CHANGER OPERATION section for information on how to use these items. 487.El 488.Sh FILES 489.Bl -tag -width /dev/cd[0-9][a-h] -compact 490.It Pa /dev/cd[0-9][a-h] 491raw mode 492.Tn CD-ROM 493devices 494.El 495.Sh DIAGNOSTICS 496None. 497.Sh SEE ALSO 498.Xr cam 4 , 499.Xr da 4 , 500.Xr disklabel 5 , 501.Xr disklabel 8 , 502.Xr cd 9 503.Sh HISTORY 504This 505.Nm 506driver is based upon the 507.Nm 508driver written by Julian Elischer, which appeared in 509.Bx 386 0.1 . 510The 511CAM version of the 512.Nm 513driver was written by Kenneth Merry and first appeared in 514.Fx 3.0 . 515.Sh BUGS 516The names of the structures used for the third argument to 517.Fn ioctl 518were poorly chosen, and a number of spelling errors have survived in 519the names of the 520.Fn ioctl 521commands. 522.Pp 523There is no mechanism currently to set different minimum and maximum 524timeouts for different CD changers; the timeout values set by the kernel 525options or the sysctl variables apply to all LUN-based CD changers in the 526system. 527It is possible to implement such support, but the sysctl 528implementation at least would be rather inelegant, because of the current 529inability of the sysctl code to handle the addition of nodes after compile 530time. 531Thus, it would take one dynamically sized sysctl variable and a 532userland utility to get/set the timeout values. 533Implementation of separate 534timeouts for different CD devices in the kernel config file would likely 535require modification of 536.Xr config 8 537to support the two timeouts when hardwiring 538.Nm 539devices. 540