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.
65 Any devices found which answer as CDROM
66 (type 5) or WORM (type 4) type devices will be `attached' to the
71 the first device found will be attached as
78 it is possible to specify what cd unit a device should
79 come on line as; refer to
81 for details on kernel configuration.
85 may be used to read the synthesized
87 structure, which will contain correct figures for the size of the
89 should that information be required.
91 .Sh KERNEL CONFIGURATION
94 devices may be attached to the system regardless of system
95 configuration as all resources are dynamically allocated.
106 .Aq Pa sys/disklabel.h .
108 .Bl -tag -width CDIOCREADSUBCHANNEL -compact
111 .Pq Li "struct disklabel"
112 Read or write the in-core copy of the disklabel for the
113 drive. The disklabel is initialized with information
114 read from the scsi inquiry commands, and should be the same as
115 the information printed at boot. This structure is defined in
118 .It Dv CDIOCCAPABILITY
119 .Pq Li "struct ioc_capability"
120 Retrieve information from the drive on what features it supports. The
121 information is returned in the following structure:
122 .Bd -literal -offset indent
123 struct ioc_capability {
124 u_long play_function;
125 #define CDDOPLAYTRK 0x00000001
126 /* Can play tracks/index */
127 #define CDDOPLAYMSF 0x00000002
128 /* Can play msf to msf */
129 #define CDDOPLAYBLOCKS 0x00000004
130 /* Can play range of blocks */
131 #define CDDOPAUSE 0x00000100
132 /* Output can be paused */
133 #define CDDORESUME 0x00000200
134 /* Output can be resumed */
135 #define CDDORESET 0x00000400
136 /* Drive can be completely reset */
137 #define CDDOSTART 0x00000800
138 /* Audio can be started */
139 #define CDDOSTOP 0x00001000
140 /* Audio can be stopped */
141 #define CDDOPITCH 0x00002000
142 /* Audio pitch can be changed */
144 u_long routing_function;
145 #define CDREADVOLUME 0x00000001
146 /* Volume settings can be read */
147 #define CDSETVOLUME 0x00000002
148 /* Volume settings can be set */
149 #define CDSETMONO 0x00000100
150 /* Output can be set to mono */
151 #define CDSETSTEREO 0x00000200
152 /* Output can be set to stereo (def) */
153 #define CDSETLEFT 0x00000400
154 /* Output can be set to left only */
155 #define CDSETRIGHT 0x00000800
156 /* Output can be set to right only */
157 #define CDSETMUTE 0x00001000
158 /* Output can be muted */
159 #define CDSETPATCH 0x00008000
160 /* Direct routing control allowed */
162 u_long special_function;
163 #define CDDOEJECT 0x00000001
164 /* The tray can be opened */
165 #define CDDOCLOSE 0x00000002
166 /* The tray can be closed */
167 #define CDDOLOCK 0x00000004
168 /* The tray can be locked */
169 #define CDREADHEADER 0x00000100
170 /* Can read Table of Contents */
171 #define CDREADENTRIES 0x00000200
172 /* Can read TOC Entries */
173 #define CDREADSUBQ 0x00000200
174 /* Can read Subchannel info */
175 #define CDREADRW 0x00000400
176 /* Can read subcodes R-W */
177 #define CDHASDEBUG 0x00004000
178 /* The tray has dynamic debugging */
181 .It Dv CDIOCPLAYTRACKS
182 .Pq Li "struct ioc_play_track"
183 Start audio playback given a track address and length. The structure
184 is defined as follows:
185 .Bd -literal -offset indent
186 struct ioc_play_track
195 .It Dv CDIOCPLAYBLOCKS
196 .Pq Li "struct ioc_play_blocks"
197 Start audio playback given a block address and length. The structure
198 is defined as follows:
199 .Bd -literal -offset indent
200 struct ioc_play_blocks
208 .Pq Li "struct ioc_play_msf"
209 Start audio playback given a `minutes-seconds-frames' address and
210 length. The structure is defined as follows:
211 .Bd -literal -offset indent
223 .It Dv CDIOCREADSUBCHANNEL
224 .Pq Li "struct ioc_read_subchannel"
225 Read information from the subchannel at the location specified by this
227 .Bd -literal -offset indent
228 struct ioc_read_subchannel {
229 u_char address_format;
230 #define CD_LBA_FORMAT 1
231 #define CD_MSF_FORMAT 2
233 #define CD_SUBQ_DATA 0
234 #define CD_CURRENT_POSITION 1
235 #define CD_MEDIA_CATALOG 2
236 #define CD_TRACK_INFO 3
239 struct cd_sub_channel_info *data;
243 .It Dv CDIOREADTOCHEADER
244 .Pq Li "struct ioc_toc_header"
245 Return summary information about the table of contents for the mounted
247 The information is returned into the following structure:
248 .Bd -literal -offset indent
249 struct ioc_toc_header {
251 u_char starting_track;
256 .It Dv CDIOREADTOCENTRYS
257 .Pq Li "struct ioc_read_toc_entry"
258 Return information from the table of contents entries mentioned. (Yes, this
259 command name is misspelled.) The argument structure is defined as follows:
260 .Bd -literal -offset indent
261 struct ioc_read_toc_entry {
262 u_char address_format;
263 u_char starting_track;
265 struct cd_toc_entry *data;
268 The requested data is written into an area of size
274 .Pq Li "struct ioc_patch"
275 Attach various audio channels to various output channels. The
276 argument structure is defined thusly:
277 .Bd -literal -offset indent
280 /* one for each channel */
286 .Pq Li "struct ioc_vol"
287 Get (set) information about the volume settings of the output channels. The
288 argument structure is as follows:
289 .Bd -literal -offset indent
293 /* one for each channel */
298 Patch all output channels to all source channels.
300 .It Dv CDIOCSETSTEREO
301 Patch left source channel to the left output channel and the right
302 source channel to the right output channel.
305 Mute output without changing the volume settings.
309 Attach both output channels to the left (right) source channel.
313 Turn on (off) debugging for the appropriate device.
317 Pause (resume) audio play, without resetting the location of the read-head.
324 Tell the drive to spin-up (-down) the
329 Tell the drive to allow (prevent) manual ejection of the
331 disc. Not all drives support this feature.
338 Tell the drive to close its door and load the media. Not all drives
339 support this feature.
342 .Pq Li "struct ioc_pitch"
343 For drives that support it, this command instructs the drive to play
344 the audio at a faster or slower rate than normal. Values of
346 between -32767 and -1 result in slower playback; a zero value
347 indicates normal speed; and values from 1 to 32767 give faster
348 playback. Drives with less than 16 bits of resolution will silently
349 ignore less-significant bits. The structure is defined thusly:
350 .Bd -literal -offset indent
360 is changed in a drive controlled by the
362 driver, then the act of changing the media will invalidate the
363 disklabel and information held within the kernel. To stop corruption,
364 all accesses to the device will be discarded until there are no more
365 open file descriptors referencing the device. During this period, all
366 new open attempts will be rejected. When no more open file descriptors
367 reference the device, the first next open will load a new set of
368 parameters (including disklabel) for the drive.
370 The audio code in the
374 standard audio commands.
377 manufacturers have not followed the standard, there are many
379 drives for which audio will not work.
380 Some work is planned to support
381 some of the more common `broken'
383 drives; however, this is not yet under way.
384 .Sh CHANGER OPERATION
385 This driver has built-in support for LUN-based CD changers. A LUN-based CD
386 changer is a drive that can hold two or more CDs, but only has one CD
387 player mechanism. Each CD in the drive shows up as a seperate logical unit
392 driver automatically recognizes LUN-based changers, and routes commands for
393 changers through an internal scheduler. The scheduler prevents changer
394 "thrashing", which is caused by sending commands to different LUNs in the
395 changer at the same time.
397 The scheduler honors minimum and maximum time
398 quanta that the driver will spend on a particular LUN. The minimum time
399 is the guaranteed minimum amount of time that the driver will spend on a
400 given LUN, even if there is no oustanding I/O for that LUN. The maximum
401 time is the maximum amount of time the changer will spend on a LUN if there
402 is oustdanding I/O for another LUN. If there is no outstanding I/O for
403 another LUN, the driver will allow indefinite access to a given LUN.
405 The minimum and maximum time quanta are configurable via kernel options and
406 also via sysctl variables. The kernel options are:
408 .Bl -tag -width 1234 -compact
409 .It Cd options "CHANGER_MIN_BUSY_SECONDS=3"
410 .It Cd options "CHANGER_MAX_BUSY_SECONDS=11"
413 The sysctl variables are:
415 .Bl -tag -width 1234 -compact
416 .It Cd kern.cam.cd.changer.min_busy_seconds
417 .It Cd kern.cam.cd.changer.max_busy_seconds
420 It is suggested that the user try experimenting with the minimum and
421 maximum timeouts via the sysctl variables to arrive at the proper values
422 for your changer. Once you have settled on the proper timeouts for your
423 changer, you can then put them in your kernel config file.
425 If your system does have a LUN-based changer, you may notice that the
426 probe messages for the various LUNs of the changer will continue to appear
427 while the boot process is going on. This is normal, and is caused by the
428 changer scheduling code.
430 .Bl -tag -width /dev/rcd[0-9][a-h] -compact
431 .It Pa /dev/cd[0-9][a-h]
435 .It Pa /dev/rcd[0-9][a-h]
449 The names of the structures used for the third argument to
451 were poorly chosen, and a number of spelling errors have survived in
456 There is no mechanism currently to set different minimum and maximum
457 timeouts for different CD changers; the timeout values set by the kernel
458 options or the sysctl variables apply to all LUN-based CD changers in the
459 system. It is possible to implement such support, but the sysctl
460 impelmentation at least would be rather inelegant, because of the current
461 inability of the sysctl code to handle the addition of nodes after compile
462 time. Thus, it would take one dynamically sized sysctl variable and a
463 userland utility to get/set the timeout values. Implementation of separate
464 timeouts for different CD devices in the kernel config file would likely
465 require modification of
467 to support the two timeouts when hardwiring
473 driver is based upon the
475 driver written by Julian Elischer, which appeared in 386BSD 0.1. The
478 driver was written by Kenneth Merry and first appeared in