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33 .Nd SCSI CD-ROM driver
36 .Cd "options ""CHANGER_MIN_BUSY_SECONDS=3"""
37 .Cd "options ""CHANGER_MAX_BUSY_SECONDS=11""
41 driver provides support for a
44 (Compact Disc-Read Only Memory) drive.
45 In an attempt to look like a regular disk, the
47 driver synthesizes a partition table, with one partition covering the entire
49 It is possible to modify this partition table using
51 but it will only last until the
54 In general the interfaces are similar to those described by
61 adapter is probed during boot, the
63 bus is scanned for devices.
64 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.
89 .Sh KERNEL CONFIGURATION
92 devices may be attached to the system regardless of system
93 configuration as all resources are dynamically allocated.
104 .In sys/disklabel.h .
105 .Bl -tag -width CDIOCREADSUBCHANNEL
108 .Pq Li "struct disklabel"
109 Read or write the in-core copy of the disklabel for the
111 The disklabel is initialized with information
112 read from the scsi inquiry commands, and should be the same as
113 the information printed at boot.
114 This structure is defined in the header file
115 .In sys/disklabel.h .
116 .It Dv CDIOCCAPABILITY
117 .Pq Li "struct ioc_capability"
118 Retrieve information from the drive on what features it supports.
119 The information is returned in the following structure:
120 .Bd -literal -offset indent
121 struct 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 */
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 */
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 */
179 .It Dv CDIOCPLAYTRACKS
180 .Pq Li "struct ioc_play_track"
181 Start audio playback given a track address and length.
182 The structure is defined as follows:
183 .Bd -literal -offset indent
184 struct ioc_play_track
192 .It Dv CDIOCPLAYBLOCKS
193 .Pq Li "struct ioc_play_blocks"
194 Start audio playback given a block address and length.
195 The structure is defined as follows:
196 .Bd -literal -offset indent
197 struct ioc_play_blocks
204 .Pq Li "struct ioc_play_msf"
205 Start audio playback given a `minutes-seconds-frames' address and
207 The structure is defined as follows:
208 .Bd -literal -offset indent
219 .It Dv CDIOCREADSUBCHANNEL
220 .Pq Li "struct ioc_read_subchannel"
221 Read information from the subchannel at the location specified by this
223 .Bd -literal -offset indent
224 struct ioc_read_subchannel {
225 u_char address_format;
226 #define CD_LBA_FORMAT 1
227 #define CD_MSF_FORMAT 2
229 #define CD_SUBQ_DATA 0
230 #define CD_CURRENT_POSITION 1
231 #define CD_MEDIA_CATALOG 2
232 #define CD_TRACK_INFO 3
235 struct cd_sub_channel_info *data;
238 .It Dv CDIOREADTOCHEADER
239 .Pq Li "struct ioc_toc_header"
240 Return summary information about the table of contents for the mounted
242 The information is returned into the following structure:
243 .Bd -literal -offset indent
244 struct ioc_toc_header {
246 u_char starting_track;
250 .It Dv CDIOREADTOCENTRYS
251 .Pq Li "struct ioc_read_toc_entry"
252 Return information from the table of contents entries mentioned.
253 .Pq Yes, this command name is misspelled.
254 The argument structure is defined as follows:
255 .Bd -literal -offset indent
256 struct ioc_read_toc_entry {
257 u_char address_format;
258 u_char starting_track;
260 struct cd_toc_entry *data;
263 The requested data is written into an area of size
268 .Pq Li "struct ioc_patch"
269 Attach various audio channels to various output channels.
270 The argument structure is defined thusly:
271 .Bd -literal -offset indent
274 /* one for each channel */
279 .Pq Li "struct ioc_vol"
280 Get (set) information about the volume settings of the output channels.
281 The argument structure is as follows:
282 .Bd -literal -offset indent
286 /* one for each channel */
290 Patch all output channels to all source channels.
291 .It Dv CDIOCSETSTEREO
292 Patch left source channel to the left output channel and the right
293 source channel to the right output channel.
295 Mute output without changing the volume settings.
298 Attach both output channels to the left (right) source channel.
301 Turn on (off) debugging for the appropriate device.
304 Pause (resume) audio play, without resetting the location of the read-head.
309 Tell the drive to spin-up (-down) the
313 Tell the drive to allow (prevent) manual ejection of the
316 Not all drives support this feature.
321 Tell the drive to close its door and load the media.
322 Not all drives support this feature.
324 .Pq Li "struct ioc_pitch"
325 For drives that support it, this command instructs the drive to play
326 the audio at a faster or slower rate than normal.
329 between -32767 and -1 result in slower playback; a zero value
330 indicates normal speed; and values from 1 to 32767 give faster
332 Drives with less than 16 bits of resolution will silently
333 ignore less-significant bits.
334 The structure is defined thusly:
335 .Bd -literal -offset indent
345 is changed in a drive controlled by the
347 driver, then the act of changing the media will invalidate the
348 disklabel and information held within the kernel.
350 all accesses to the device will be discarded until there are no more
351 open file descriptors referencing the device.
352 During this period, all
353 new open attempts will be rejected.
354 When no more open file descriptors
355 reference the device, the first next open will load a new set of
356 parameters (including disklabel) for the drive.
358 The audio code in the
362 standard audio commands.
365 manufacturers have not followed the standard, there are many
367 drives for which audio will not work.
368 Some work is planned to support
369 some of the more common `broken'
371 drives; however, this is not yet under way.
372 .Sh CHANGER OPERATION
373 This driver has built-in support for LUN-based CD changers.
375 changer is a drive that can hold two or more CDs, but only has one CD
377 Each CD in the drive shows up as a separate logical unit
383 driver automatically recognizes LUN-based changers, and routes commands for
384 changers through an internal scheduler.
385 The scheduler prevents changer
386 "thrashing", which is caused by sending commands to different LUNs in the
387 changer at the same time.
389 The scheduler honors minimum and maximum time
390 quanta that the driver will spend on a particular LUN.
392 is the guaranteed minimum amount of time that the driver will spend on a
393 given LUN, even if there is no outstanding I/O for that LUN.
395 time is the maximum amount of time the changer will spend on a LUN if there
396 is outstanding I/O for another LUN.
397 If there is no outstanding I/O for
398 another LUN, the driver will allow indefinite access to a given LUN.
400 The minimum and maximum time quanta are configurable via kernel options and
401 also via sysctl and kernel tunable variables.
402 The kernel options are:
406 .Cd "options ""CHANGER_MIN_BUSY_SECONDS=3"""
408 .Cd "options ""CHANGER_MAX_BUSY_SECONDS=11"""
411 The sysctl/kernel tunable variables are:
415 .Va kern.cam.cd.changer.min_busy_seconds
417 .Va 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
423 Once you have settled on the proper timeouts for your
424 changer, you can then put them in your kernel config file.
426 If your system does have a LUN-based changer, you may notice that the
427 probe messages for the various LUNs of the changer will continue to appear
428 while the boot process is going on.
429 This is normal, and is caused by the
430 changer scheduling code.
432 The following variables are available as both
438 .It kern.cam.cd.retry_count
440 This variable determines how many times the
442 driver will retry a READ or WRITE command.
443 This does not affect the number of retries used during probe time or for
447 This value currently defaults to 4.
448 .It kern.cam.cd.%d.minimum_cmd_size
452 driver attempts to automatically determine whether the drive it is talking
453 to supports 6 byte or 10 byte MODE SENSE/MODE SELECT operations.
456 drives only support 6 byte commands, and
458 drives only support 10 byte commands.
461 driver first attempts to determine whether the protocol in use typically
462 supports 6 byte commands by issuing a CAM Path Inquiry CCB.
463 It will then default to 6 byte or 10 byte commands as appropriate.
466 driver defaults to using 6 byte commands (assuming the protocol the drive
467 speaks claims to support 6 byte commands), until one fails with a
469 ILLEGAL REQUEST error.
470 Then it tries the 10 byte version of the command to
471 see if that works instead.
472 Users can change the default via per-drive
473 sysctl variables and loader tunables.
476 is the unit number of the drive in question.
477 Valid minimum command sizes
479 Any value above 6 will be rounded to 10, and any value below
480 6 will be rounded to 6.
481 .It kern.cam.cd.changer.min_busy_seconds
482 .It kern.cam.cd.changer.max_busy_seconds
484 Tune how long individual LUNs are 'locked' for I/O operations to
485 optimize changer operation.
486 See CHANGER OPERATION section for information on how to use these items.
489 .Bl -tag -width /dev/cd[0-9][a-h] -compact
490 .It Pa /dev/cd[0-9][a-h]
505 driver is based upon the
507 driver written by Julian Elischer, which appeared in
512 driver was written by Kenneth Merry and first appeared in
515 The names of the structures used for the third argument to
517 were poorly chosen, and a number of spelling errors have survived in
522 There is no mechanism currently to set different minimum and maximum
523 timeouts for different CD changers; the timeout values set by the kernel
524 options or the sysctl variables apply to all LUN-based CD changers in the
526 It is possible to implement such support, but the sysctl
527 implementation at least would be rather inelegant, because of the current
528 inability of the sysctl code to handle the addition of nodes after compile
530 Thus, it would take one dynamically sized sysctl variable and a
531 userland utility to get/set the timeout values.
532 Implementation of separate
533 timeouts for different CD devices in the kernel config file would likely
534 require modification of
536 to support the two timeouts when hardwiring