1 .. SPDX-License-Identifier: GPL-2.0
2
3 =========================
4 SCSI media changer driver
5 =========================
6
7 This is a driver for SCSI Medium Changer devic
8 with "Type: Medium Changer" in /proc/scsi/scsi
9
10 This is for *real* Jukeboxes. It is *not* sup
11 common small CD-ROM changers, neither one-lun-
12 nor IDE drives.
13
14 Userland tools available from here:
15 http://linux.bytesex.org/misc/changer.
16
17
18 General Information
19 -------------------
20
21 First some words about how changers work: A ch
22 more) SCSI ID's. One for the changer device wh
23 and one for the device which actually reads an
24 later may be anything, a MOD, a CD-ROM, a tape
25 changer device this is a "don't care", he *onl
26 media, nothing else.
27
28
29 The SCSI changer model is complex, compared to
30 changers. But it allows to handle nearly all p
31 4 different types of changer elements:
32
33 =============== ==========================
34 media transport this one shuffles around t
35 transport arm. Also known
36 storage a slot which can hold a me
37 import/export the same as above, but is
38 i.e. there the operator (y
39 fill in and remove media f
40 Sometimes named "mailslot"
41 data transfer this is the device which r
42 CD-ROM / Tape / whatever d
43 =============== ==========================
44
45 None of these is limited to one: A huge Jukebo
46 123 CD-ROM's, 5 CD-ROM readers (and therefore
47 and each CD-ROM) and 2 transport arms. No prob
48
49
50 How it is implemented
51 ---------------------
52
53 I implemented the driver as character device d
54 ioctl interface. Just grabbed NetBSD's header
55 other linux SCSI device drivers as starting po
56 should be source code compatible with NetBSD.
57 software (anybody knows ???) which supports a
58 it should work with this driver too.
59
60 Over time a few more ioctls where added, volum
61 wasn't covered by the NetBSD ioctl API.
62
63
64 Current State
65 -------------
66
67 Support for more than one transport arm is not
68 nobody asked for it so far...).
69
70 I test and use the driver myself with a 35 slo
71 Grundig. I got some reports telling it works
72 (Exabyte, HP and DEC). Some People use this d
73 works fine with small (11 slots) and a huge (4
74 magneto-optical Jukebox. Probably with lots o
75 (but not all :-) people mail me only if it doe
76
77 I don't have any device lists, neither black-l
78 it is quite useless to ask me whenever a speci
79 not. In theory every changer device which sup
80 changer command set should work out-of-the-box
81 doesn't, it is a bug. Either within the drive
82 of the changer device.
83
84
85 Using it
86 --------
87
88 This is a character device with major number i
89 "mknod /dev/sch0 c 86 0" to create the special
90
91 If the module finds the changer, it prints som
92 device [ try "dmesg" if you don't see anything
93 /proc/devices. If not.... some changers use I
94 device and ID ? / LUN 1 for the robot mechanis
95 look for LUNs other than 0 as default, because
96 broken devices. So you can try:
97
98 1) echo "scsi add-single-device 0 0 ID 1" >
99 (replace ID with the SCSI-ID of the devic
100 2) boot the kernel with "max_scsi_luns=1" on
101 (append="max_scsi_luns=1" in lilo.conf sh
102
103
104 Trouble?
105 --------
106
107 If you insmod the driver with "insmod debug=1"
108 prints a lot of stuff to the syslog. Compilin
109 CONFIG_SCSI_CONSTANTS=y improves the quality o
110 because the kernel will translate the error co
111 strings then.
112
113 You can display these messages with the dmesg
114 logfiles). If you email me some question beca
115 driver, please include these messages.
116
117
118 Insmod options
119 --------------
120
121 debug=0/1
122 Enable debug messages (see above, defa
123
124 verbose=0/1
125 Be verbose (default: 1).
126
127 init=0/1
128 Send INITIALIZE ELEMENT STATUS command
129 at insmod time (default: 1).
130
131 timeout_init=<seconds>
132 timeout for the INITIALIZE ELEMENT STA
133 (default: 3600).
134
135 timeout_move=<seconds>
136 timeout for all other commands (defaul
137
138 dt_id=<id1>,<id2>,... / dt_lun=<lun1>,<lun2>,.
139 These two allow to specify the SCSI ID
140 transfer elements. You likely don't n
141 should provide this information. But
142
143 vendor_firsts=, vendor_counts=, vendor_labels=
144 These insmod options can be used to te
145 are some vendor-specific element types
146 does this. Some jukeboxes have a prin
147 CDs, which is addressed as element 0xc
148 driver about this vendor-specific elem
149
150 $ insmod ch
151 vendor_firsts=0xc000
152 vendor_counts=1
153 vendor_labels=printer
154
155 All three insmod options accept up to
156 values, this way you can configure the
157 You likely need the SCSI specs for the
158 find the correct values as they are no
159 standard.
160
161
162 Credits
163 -------
164
165 I wrote this driver using the famous mailing-p
166 method. With (more or less) help from:
167
168 - Daniel Moehwald <moehwald@hdg.de>
169 - Dane Jasper <dane@sonic.net>
170 - R. Scott Bailey <sbailey@dsddi.eds.co
171 - Jonathan Corbet <corbet@lwn.net>
172
173 Special thanks go to
174
175 - Martin Kuehne <martin.kuehne@bnbt.de>
176
177 for a old, second-hand (but full functional) c
178 to develop/test driver and tools now.
179
180 Have fun,
181
182 Gerd
183
184 Gerd Knorr <kraxel@bytesex.org>
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