2 .\" Julian Elischer <julian@freebsd.org>. All rights reserved.
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33 .Nd SCSI CD-ROM driver
36 .Cd device cd1 at scbus0 target 4 unit 0
37 .Cd options "CHANGER_MIN_BUSY_SECONDS=3"
38 .Cd options "CHANGER_MAX_BUSY_SECONDS=11"
42 driver provides support for a
45 (Compact Disc-Read Only Memory) drive.
46 In an attempt to look like a regular disk, the
48 driver synthesizes a partition table, with one partition covering the entire
50 It is possible to modify this partition table using
52 but it will only last until the
55 In general the interfaces are similar to those described by
62 adapter is probed during boot, the
64 bus is scanned for devices. Any devices found which answer as CDROM
65 (type 5) or WORM (type 4) type devices will be `attached' to the
70 the first device found will be attached as
77 it is possible to specify what cd unit a device should
78 come on line as; refer to
80 for details on kernel configuration.
84 may be used to read the synthesized
86 structure, which will contain correct figures for the size of the
88 should that information be required.
90 .Sh KERNEL CONFIGURATION
93 devices may be attached to the system regardless of system
94 configuration as all resources are dynamically allocated.
105 .Aq Pa sys/disklabel.h .
107 .Bl -tag -width CDIOCREADSUBCHANNEL -compact
110 .Pq Li "struct disklabel"
111 Read or write the in-core copy of the disklabel for the
112 drive. The disklabel is initialized with information
113 read from the scsi inquiry commands, and should be the same as
114 the information printed at boot. This structure is defined in
117 .It Dv CDIOCCAPABILITY
118 .Pq Li "struct ioc_capability"
119 Retrieve information from the drive on what features it supports. The
120 information is returned in the following structure:
121 .Bd -literal -offset indent
122 struct 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 */
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 */
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 */
180 .It Dv CDIOCPLAYTRACKS
181 .Pq Li "struct ioc_play_track"
182 Start audio playback given a track address and length. The structure
183 is defined as follows:
184 .Bd -literal -offset indent
185 struct ioc_play_track
194 .It Dv CDIOCPLAYBLOCKS
195 .Pq Li "struct ioc_play_blocks"
196 Start audio playback given a block address and length. The structure
197 is defined as follows:
198 .Bd -literal -offset indent
199 struct ioc_play_blocks
207 .Pq Li "struct ioc_play_msf"
208 Start audio playback given a `minutes-seconds-frames' address and
209 length. The structure is defined as follows:
210 .Bd -literal -offset indent
222 .It Dv CDIOCREADSUBCHANNEL
223 .Pq Li "struct ioc_read_subchannel"
224 Read information from the subchannel at the location specified by this
226 .Bd -literal -offset indent
227 struct ioc_read_subchannel {
228 u_char address_format;
229 #define CD_LBA_FORMAT 1
230 #define CD_MSF_FORMAT 2
232 #define CD_SUBQ_DATA 0
233 #define CD_CURRENT_POSITION 1
234 #define CD_MEDIA_CATALOG 2
235 #define CD_TRACK_INFO 3
238 struct cd_sub_channel_info *data;
242 .It Dv CDIOREADTOCHEADER
243 .Pq Li "struct ioc_toc_header"
244 Return summary information about the table of contents for the mounted
246 The information is returned into the following structure:
247 .Bd -literal -offset indent
248 struct ioc_toc_header {
250 u_char starting_track;
255 .It Dv CDIOREADTOCENTRYS
256 .Pq Li "struct ioc_read_toc_entry"
257 Return information from the table of contents entries mentioned. (Yes, this
258 command name is misspelled.) The argument structure is defined as follows:
259 .Bd -literal -offset indent
260 struct ioc_read_toc_entry {
261 u_char address_format;
262 u_char starting_track;
264 struct cd_toc_entry *data;
267 The requested data is written into an area of size
273 .Pq Li "struct ioc_patch"
274 Attach various audio channels to various output channels. The
275 argument structure is defined thusly:
276 .Bd -literal -offset indent
279 /* one for each channel */
285 .Pq Li "struct ioc_vol"
286 Get (set) information about the volume settings of the output channels. The
287 argument structure is as follows:
288 .Bd -literal -offset indent
292 /* one for each channel */
297 Patch all output channels to all source channels.
299 .It Dv CDIOCSETSTEREO
300 Patch left source channel to the left output channel and the right
301 source channel to the right output channel.
304 Mute output without changing the volume settings.
308 Attach both output channels to the left (right) source channel.
312 Turn on (off) debugging for the appropriate device.
316 Pause (resume) audio play, without resetting the location of the read-head.
323 Tell the drive to spin-up (-down) the
328 Tell the drive to allow (prevent) manual ejection of the
330 disc. Not all drives support this feature.
337 Tell the drive to close its door and load the media. Not all drives
338 support this feature.
341 .Pq Li "struct ioc_pitch"
342 For drives that support it, this command instructs the drive to play
343 the audio at a faster or slower rate than normal. Values of
345 between -32767 and -1 result in slower playback; a zero value
346 indicates normal speed; and values from 1 to 32767 give faster
347 playback. Drives with less than 16 bits of resolution will silently
348 ignore less-significant bits. The structure is defined thusly:
349 .Bd -literal -offset indent
359 is changed in a drive controlled by the
361 driver, then the act of changing the media will invalidate the
362 disklabel and information held within the kernel. To stop corruption,
363 all accesses to the device will be discarded until there are no more
364 open file descriptors referencing the device. During this period, all
365 new open attempts will be rejected. When no more open file descriptors
366 reference the device, the first next open will load a new set of
367 parameters (including disklabel) for the drive.
369 The audio code in the
373 standard audio commands. Because many
375 manufacturers have not followed the standard, there are many
377 drives for which audio will not work. Some work is planned to support
378 some of the more common `broken'
380 drives; however, this is not yet under way.
381 .Sh CHANGER OPERATION
382 This driver has built-in support for LUN-based CD changers. A LUN-based CD
383 changer is a drive that can hold two or more CDs, but only has one CD
384 player mechanism. Each CD in the drive shows up as a seperate logical unit
389 driver automatically recognizes LUN-based changers, and routes commands for
390 changers through an internal scheduler. The scheduler prevents changer
391 "thrashing", which is caused by sending commands to different LUNs in the
392 changer at the same time.
394 The scheduler honors minimum and maximum time
395 quanta that the driver will spend on a particular LUN. The minimum time
396 is the guaranteed minimum amount of time that the driver will spend on a
397 given LUN, even if there is no oustanding I/O for that LUN. The maximum
398 time is the maximum amount of time the changer will spend on a LUN if there
399 is oustdanding I/O for another LUN. If there is no outstanding I/O for
400 another LUN, the driver will allow indefinite access to a given LUN.
402 The minimum and maximum time quanta are configurable via kernel options and
403 also via sysctl variables. The kernel options are:
405 .Bl -tag -width 1234 -compact
406 .It Cd options "CHANGER_MIN_BUSY_SECONDS=3"
407 .It Cd options "CHANGER_MAX_BUSY_SECONDS=11"
410 The sysctl variables are:
412 .Bl -tag -width 1234 -compact
413 .It Cd kern.cam.cd.changer.min_busy_seconds
414 .It Cd kern.cam.cd.changer.max_busy_seconds
417 It is suggested that the user try experimenting with the minimum and
418 maximum timeouts via the sysctl variables to arrive at the proper values
419 for your changer. Once you have settled on the proper timeouts for your
420 changer, you can then put them in your kernel config file.
422 If your system does have a LUN-based changer, you may notice that the
423 probe messages for the various LUNs of the changer will continue to appear
424 while the boot process is going on. This is normal, and is caused by the
425 changer scheduling code.
427 .Bl -tag -width /dev/rcd[0-9][a-h] -compact
428 .It Pa /dev/cd[0-9][a-h]
432 .It Pa /dev/rcd[0-9][a-h]
446 The names of the structures used for the third argument to
448 were poorly chosen, and a number of spelling errors have survived in
453 There is no mechanism currently to set different minimum and maximum
454 timeouts for different CD changers; the timeout values set by the kernel
455 options or the sysctl variables apply to all LUN-based CD changers in the
456 system. It is possible to implement such support, but the sysctl
457 impelmentation at least would be rather inelegant, because of the current
458 inability of the sysctl code to handle the addition of nodes after compile
459 time. Thus, it would take one dynamically sized sysctl variable and a
460 userland utility to get/set the timeout values. Implementation of separate
461 timeouts for different CD devices in the kernel config file would likely
462 require modification of
464 to support the two timeouts when hardwiring
470 driver is based upon the
472 driver written by Julian Elischer, which appeared in 386BSD 0.1. The
475 driver was written by Kenneth Merry and first appeared in