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: src/share/man/man4/cd.4,v 1.17.2.8 2003/06/03 14:32:09 hmp Exp $ 27.\" $DragonFly: src/share/man/man4/cd.4,v 1.6 2008/05/02 02:05:05 swildner Exp $ 28.\" 29.Dd October 10, 1998 30.Dt CD 4 31.Os 32.Sh NAME 33.Nm cd 34.Nd SCSI CD-ROM driver 35.Sh SYNOPSIS 36.Cd device cd 37.Cd device cd1 at scbus0 target 4 unit 0 38.Cd "options CHANGER_MIN_BUSY_SECONDS=3" 39.Cd "options CHANGER_MAX_BUSY_SECONDS=11" 40.Sh DESCRIPTION 41The 42.Nm 43driver provides support for a 44.Tn SCSI 45.Tn CD-ROM 46(Compact Disc-Read Only Memory) drive. 47In an attempt to look like a regular disk, the 48.Nm 49driver synthesizes a partition table, with one partition covering the entire 50.Tn CD-ROM . 51It is possible to modify this partition table using 52.Xr disklabel 8 , 53but it will only last until the 54.Tn CD-ROM 55is unmounted. 56In general the interfaces are similar to those described by 57.Xr ad 4 58and 59.Xr da 4 . 60.Pp 61As the 62.Tn SCSI 63adapter is probed during boot, the 64.Tn SCSI 65bus is scanned for devices. 66Any devices found which answer as CDROM 67(type 5) or WORM (type 4) type devices will be `attached' to the 68.Nm 69driver. 70Prior to 71.Fx 2.1 , 72the first device found will be attached as 73.Li cd0 74the next, 75.Li cd1 , 76etc. 77Beginning in 78.Fx 2.1 79it is possible to specify what cd unit a device should 80come on line as; refer to 81.Xr scsi 4 82for details on kernel configuration. 83.Pp 84The 85.Cd target 86string is followed by the device's standard 87.Tn SCSI 88device ID number. 89The 90.Cd unit 91string is followed by the Logical Unit Number 92.Pq Tn LUN 93of the 94.Tn SCSI 95device's sub-device, if any, or zero. 96.Pp 97The system utility 98.Xr disklabel 8 99may be used to read the synthesized 100disk label 101structure, which will contain correct figures for the size of the 102.Tn CD-ROM 103should that information be required. 104.Sh KERNEL CONFIGURATION 105Any number of 106.Tn CD-ROM 107devices may be attached to the system regardless of system 108configuration as all resources are dynamically allocated. 109.Sh IOCTLS 110The following 111.Xr ioctl 2 112calls which apply to 113.Tn SCSI 114.Tn CD-ROM 115drives are defined 116in the header files 117.In sys/cdio.h 118and 119.In sys/disklabel.h . 120.Bl -tag -width ".Dv CDIOCREADSUBCHANNEL" 121.It Dv DIOCGDINFO 122.It Dv DIOCSDINFO 123.Pq Li "struct disklabel" 124Read or write the in-core copy of the disklabel for the 125drive. 126The disklabel is initialized with information 127read from the scsi inquiry commands, and should be the same as 128the information printed at boot. 129This structure is defined in 130.Xr disklabel 5 . 131.It Dv CDIOCCAPABILITY 132.Pq Li "struct ioc_capability" 133Retrieve information from the drive on what features it supports. 134The information is returned in the following structure: 135.Bd -literal -offset indent 136struct ioc_capability { 137 u_long play_function; 138#define CDDOPLAYTRK 0x00000001 139 /* Can play tracks/index */ 140#define CDDOPLAYMSF 0x00000002 141 /* Can play msf to msf */ 142#define CDDOPLAYBLOCKS 0x00000004 143 /* Can play range of blocks */ 144#define CDDOPAUSE 0x00000100 145 /* Output can be paused */ 146#define CDDORESUME 0x00000200 147 /* Output can be resumed */ 148#define CDDORESET 0x00000400 149 /* Drive can be completely reset */ 150#define CDDOSTART 0x00000800 151 /* Audio can be started */ 152#define CDDOSTOP 0x00001000 153 /* Audio can be stopped */ 154#define CDDOPITCH 0x00002000 155 /* Audio pitch can be changed */ 156 157 u_long routing_function; 158#define CDREADVOLUME 0x00000001 159 /* Volume settings can be read */ 160#define CDSETVOLUME 0x00000002 161 /* Volume settings can be set */ 162#define CDSETMONO 0x00000100 163 /* Output can be set to mono */ 164#define CDSETSTEREO 0x00000200 165 /* Output can be set to stereo (def) */ 166#define CDSETLEFT 0x00000400 167 /* Output can be set to left only */ 168#define CDSETRIGHT 0x00000800 169 /* Output can be set to right only */ 170#define CDSETMUTE 0x00001000 171 /* Output can be muted */ 172#define CDSETPATCH 0x00008000 173 /* Direct routing control allowed */ 174 175 u_long special_function; 176#define CDDOEJECT 0x00000001 177 /* The tray can be opened */ 178#define CDDOCLOSE 0x00000002 179 /* The tray can be closed */ 180#define CDDOLOCK 0x00000004 181 /* The tray can be locked */ 182#define CDREADHEADER 0x00000100 183 /* Can read Table of Contents */ 184#define CDREADENTRIES 0x00000200 185 /* Can read TOC Entries */ 186#define CDREADSUBQ 0x00000200 187 /* Can read Subchannel info */ 188#define CDREADRW 0x00000400 189 /* Can read subcodes R-W */ 190#define CDHASDEBUG 0x00004000 191 /* The tray has dynamic debugging */ 192}; 193.Ed 194.It Dv CDIOCPLAYTRACKS 195.Pq Li "struct ioc_play_track" 196Start audio playback given a track address and length. 197The structure is defined as follows: 198.Bd -literal -offset indent 199struct ioc_play_track 200{ 201 u_char start_track; 202 u_char start_index; 203 u_char end_track; 204 u_char end_index; 205}; 206.Ed 207.It Dv CDIOCPLAYBLOCKS 208.Pq Li "struct ioc_play_blocks" 209Start audio playback given a block address and length. 210The structure is defined as follows: 211.Bd -literal -offset indent 212struct ioc_play_blocks 213{ 214 int blk; 215 int len; 216}; 217.Ed 218.It Dv CDIOCPLAYMSF 219.Pq Li "struct ioc_play_msf" 220Start audio playback given a `minutes-seconds-frames' address and 221length. 222The structure is defined as follows: 223.Bd -literal -offset indent 224struct ioc_play_msf 225{ 226 u_char start_m; 227 u_char start_s; 228 u_char start_f; 229 u_char end_m; 230 u_char end_s; 231 u_char end_f; 232}; 233.Ed 234.It Dv CDIOCREADSUBCHANNEL 235.Pq Li "struct ioc_read_subchannel" 236Read information from the subchannel at the location specified by this 237structure: 238.Bd -literal -offset indent 239struct ioc_read_subchannel { 240 u_char address_format; 241#define CD_LBA_FORMAT 1 242#define CD_MSF_FORMAT 2 243 u_char data_format; 244#define CD_SUBQ_DATA 0 245#define CD_CURRENT_POSITION 1 246#define CD_MEDIA_CATALOG 2 247#define CD_TRACK_INFO 3 248 u_char track; 249 int data_len; 250 struct cd_sub_channel_info *data; 251}; 252.Ed 253.It Dv CDIOREADTOCHEADER 254.Pq Li "struct ioc_toc_header" 255Return summary information about the table of contents for the mounted 256.Tn CD-ROM . 257The information is returned into the following structure: 258.Bd -literal -offset indent 259struct ioc_toc_header { 260 u_short len; 261 u_char starting_track; 262 u_char ending_track; 263}; 264.Ed 265.It Dv CDIOREADTOCENTRYS 266.Pq Li "struct ioc_read_toc_entry" 267Return information from the table of contents entries mentioned. 268.Pq Yes, this command name is misspelled. 269The argument structure is defined as follows: 270.Bd -literal -offset indent 271struct ioc_read_toc_entry { 272 u_char address_format; 273 u_char starting_track; 274 u_short data_len; 275 struct cd_toc_entry *data; 276}; 277.Ed 278The requested data is written into an area of size 279.Li data_len 280and pointed to by 281.Li data . 282.It Dv CDIOCSETPATCH 283.Pq Li "struct ioc_patch" 284Attach various audio channels to various output channels. 285The argument structure is defined thusly: 286.Bd -literal -offset indent 287struct ioc_patch { 288 u_char patch[4]; 289 /* one for each channel */ 290}; 291.Ed 292.It Dv CDIOCGETVOL 293.It Dv CDIOCSETVOL 294.Pq Li "struct ioc_vol" 295Get (set) information about the volume settings of the output channels. 296The argument structure is as follows: 297.Bd -literal -offset indent 298struct ioc_vol 299{ 300 u_char vol[4]; 301 /* one for each channel */ 302}; 303.Ed 304.It Dv CDIOCSETMONO 305Patch all output channels to all source channels. 306.It Dv CDIOCSETSTEREO 307Patch left source channel to the left output channel and the right 308source channel to the right output channel. 309.It Dv CDIOCSETMUTE 310Mute output without changing the volume settings. 311.It Dv CDIOCSETLEFT 312.It Dv CDIOCSETRIGHT 313Attach both output channels to the left (right) source channel. 314.It Dv CDIOCSETDEBUG 315.It Dv CDIOCCLRDEBUG 316Turn on (off) debugging for the appropriate device. 317.It Dv CDIOCPAUSE 318.It Dv CDIOCRESUME 319Pause (resume) audio play, without resetting the location of the read-head. 320.It Dv CDIOCRESET 321Reset the drive. 322.It Dv CDIOCSTART 323.It Dv CDIOCSTOP 324Tell the drive to spin-up (-down) the 325.Tn CD-ROM . 326.It Dv CDIOCALLOW 327.It Dv CDIOCPREVENT 328Tell the drive to allow (prevent) manual ejection of the 329.Tn CD-ROM 330disc. Not all drives support this feature. 331.It Dv CDIOCEJECT 332Eject the 333.Tn CD-ROM . 334.It Dv CDIOCCLOSE 335Tell the drive to close its door and load the media. 336Not all drives support this feature. 337.It Dv CDIOCPITCH 338.Pq Li "struct ioc_pitch" 339For drives that support it, this command instructs the drive to play 340the audio at a faster or slower rate than normal. 341Values of 342.Li speed 343between -32767 and -1 result in slower playback; a zero value 344indicates normal speed; and values from 1 to 32767 give faster 345playback. 346Drives with less than 16 bits of resolution will silently 347ignore less-significant bits. 348The structure is defined thusly: 349.Bd -literal -offset indent 350struct ioc_pitch 351{ 352 short speed; 353}; 354.Ed 355.El 356.Sh NOTES 357When a 358.Tn CD-ROM 359is changed in a drive controlled by the 360.Nm 361driver, then the act of changing the media will invalidate the 362disklabel and information held within the kernel. 363To stop corruption, 364all accesses to the device will be discarded until there are no more 365open file descriptors referencing the device. 366During this period, all 367new open attempts will be rejected. 368When no more open file descriptors 369reference the device, the first next open will load a new set of 370parameters (including disklabel) for the drive. 371.Pp 372The audio code in the 373.Nm 374driver only support 375.Tn SCSI-2 376standard audio commands. 377Because many 378.Tn CD-ROM 379manufacturers have not followed the standard, there are many 380.Tn CD-ROM 381drives for which audio will not work. 382Some work is planned to support 383some of the more common `broken' 384.Tn CD-ROM 385drives; however, this is not yet under way. 386.Sh CHANGER OPERATION 387This driver has built-in support for LUN-based CD changers. 388A LUN-based CD 389changer is a drive that can hold two or more CDs, but only has one CD 390player mechanism. 391Each CD in the drive shows up as a separate logical unit 392on the 393.Tn SCSI 394bus. The 395.Nm 396driver automatically recognizes LUN-based changers, and routes commands for 397changers through an internal scheduler. 398The scheduler prevents changer 399"thrashing", which is caused by sending commands to different LUNs in the 400changer at the same time. 401.Pp 402The scheduler honors minimum and maximum time 403quanta that the driver will spend on a particular LUN. 404The minimum time 405is the guaranteed minimum amount of time that the driver will spend on a 406given LUN, even if there is no outstanding I/O for that LUN. 407The maximum 408time is the maximum amount of time the changer will spend on a LUN if there 409is outstanding I/O for another LUN. 410If there is no outstanding I/O for 411another LUN, the driver will allow indefinite access to a given LUN. 412.Pp 413The minimum and maximum time quanta are configurable via kernel options and 414also via sysctl variables. 415The kernel options are: 416.Pp 417.Bl -item -compact 418.It 419.Cd "options ""CHANGER_MIN_BUSY_SECONDS=3""" 420.It 421.Cd "options ""CHANGER_MAX_BUSY_SECONDS=11""" 422.El 423.Pp 424The sysctl variables are: 425.Pp 426.Bl -item -compact 427.It 428.Va kern.cam.cd.changer.min_busy_seconds 429.It 430.Va kern.cam.cd.changer.max_busy_seconds 431.El 432.Pp 433It is suggested that the user try experimenting with the minimum and 434maximum timeouts via the sysctl variables to arrive at the proper values 435for your changer. 436Once you have settled on the proper timeouts for your 437changer, you can then put them in your kernel config file. 438.Pp 439If your system does have a LUN-based changer, you may notice that the 440probe messages for the various LUNs of the changer will continue to appear 441while the boot process is going on. 442This is normal, and is caused by the 443changer scheduling code. 444.Sh FILES 445.Bl -tag -width /dev/cd[0-9][a-h] -compact 446.It Pa /dev/cd[0-9][a-h] 447raw mode 448.Tn CD-ROM 449devices 450.El 451.Sh DIAGNOSTICS 452None. 453.Sh SEE ALSO 454.Xr da 4 , 455.Xr scsi 4 , 456.Xr disklabel 5 , 457.Xr disklabel 8 , 458.Xr cd 9 459.Sh HISTORY 460This 461.Nm 462driver is based upon the 463.Nm 464driver written by Julian Elischer, which appeared in 465.Bx 386 0.1 . 466The 467CAM version of the 468.Nm 469driver was written by Kenneth Merry and first appeared in 470.Fx 3.0 . 471.Sh BUGS 472The names of the structures used for the third argument to 473.Fn ioctl 474were poorly chosen, and a number of spelling errors have survived in 475the names of the 476.Fn ioctl 477commands. 478.Pp 479There is no mechanism currently to set different minimum and maximum 480timeouts for different CD changers; the timeout values set by the kernel 481options or the sysctl variables apply to all LUN-based CD changers in the 482system. 483It is possible to implement such support, but the sysctl 484implementation at least would be rather inelegant, because of the current 485inability of the sysctl code to handle the addition of nodes after compile 486time. 487Thus, it would take one dynamically sized sysctl variable and a 488userland utility to get/set the timeout values. 489Implementation of separate 490timeouts for different CD devices in the kernel config file would likely 491require modification of 492.Xr config 8 493to support the two timeouts when hardwiring 494.Nm 495devices. 496