kernel: Remove some old ISA only drivers.
[dragonfly.git] / share / man / man4 / scsi.4
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1.\" Copyright (c) 1996
2.\" Julian Elischer <julian@FreeBSD.org>. All rights reserved.
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26.\" $FreeBSD: src/share/man/man4/scsi.4,v 1.18.2.7 2001/08/17 13:08:39 ru Exp $
27.Dd October 15, 1998
28.Dt SCSI 4
29.Os
30.Sh NAME
31.Nm SCSI ,
32.Nm CAM
33.Nd CAM SCSI subsystem
34.Sh SYNOPSIS
35.Cd "device scbus"
36.Cd "device scbus1 at ahc0"
37.Cd "device scbus3 at ahc1 bus 0"
38.Cd "device scbus2 at ahc1 bus 1"
39.Cd "device cd"
40.Cd "device ch"
41.Cd "device da"
42.Cd "device pass"
43.Cd "device pt"
44.Cd "device sa"
45.Cd "device ch1 at scbus0 target 4 unit 0"
46.Cd "options CAMDEBUG"
47.Cd "options CAM_DEBUG_BUS=-1"
48.Cd "options CAM_DEBUG_TARGET=-1"
49.Cd "options CAM_DEBUG_LUN=-1"
50.Cd "options CAM_DEBUG_FLAGS=CAM_DEBUG_INFO|CAM_DEBUG_CDB"
51.Cd "options CAM_MAX_HIGHPOWER=4"
52.Cd "options SCSI_NO_SENSE_STRINGS"
53.Cd "options SCSI_NO_OP_STRINGS"
54.Cd "options SCSI_DELAY=8000"
55.Sh DESCRIPTION
56The CAM
57.Tn SCSI
58subsystem provides a uniform and modular system for the implementation
59of drivers to control various
60.Tn SCSI
61devices, and to utilize different
62.Tn SCSI
63host adapters through host adapter drivers.
64When the system probes the
65.Tn SCSI
66busses, it attaches any devices it finds to the appropriate
67drivers. The
68.Xr pass 4
69driver, if it is configured in the kernel, will attach to all
70.Tn SCSI
71devices.
72.Sh KERNEL CONFIGURATION
73There are a number of generic kernel configuration options for the
74CAM
75.Tn SCSI
76subsystem:
77.Bl -tag -width SCSI_NO_SENSE_STRINGS
78.It Dv CAMDEBUG
79This option enables the CAM debugging printf code. This won't actually
80cause any debugging information to be printed out when included by itself.
81Enabling printouts requires additional configuration. See below for
82details.
83.It Dv "CAM_MAX_HIGHPOWER=4"
84This sets the maximum allowable number of concurrent "high power" commands.
85A "high power" command is a command that takes more electrical power than
86most to complete. An example of this (and the only command currently
87tagged as "high power") is the
88.Tn SCSI
89START UNIT command. Starting a SCSI disk often takes significantly more
90electrical power than normal operation of the disk. This option allows the
91user to specify how many concurrent high power commands may be outstanding
92without overloading the power supply on his computer.
93.It Dv SCSI_NO_SENSE_STRINGS
94This eliminates text descriptions of each
95.Tn SCSI
96Additional Sense Code and Additional Sense Code Qualifier pair. Since this
97is a fairly large text database, eliminating it reduces the size of the
98kernel somewhat. This is primarily necessary for boot floppies and other
99low disk space or low memory space environments. In most cases, though,
100this should be enabled, since it speeds the interpretation of
101.Tn SCSI
102error messages. Don't let the "kernel bloat" zealots get to you -- leave
103the sense descriptions in your kernel!
104.It Dv SCSI_NO_OP_STRINGS
105This disables text descriptions of each
106.Tn SCSI
107opcode. This option, like the sense string option above, is primarily
108useful for environments like a boot floppy where kernel size is critical.
109Enabling this option for normal use isn't recommended, since it slows
110debugging of
111.Tn SCSI
112problems.
113.It Dv SCSI_DELAY=8000
114This is the
115.Tn SCSI
116"bus settle delay." In CAM, it is specified in
117.Em milliseconds ,
118not seconds like the old
119.Tn SCSI
120layer used to do. When the kernel boots, it sends a bus reset to each
121.Tn SCSI
122bus to tell each device to reset itself to a default set of transfer
123negotiations and other settings. Most
124.Tn SCSI
125devices need some amount of time to recover from a bus reset. Newer disks
126may need as little as 100ms, while old, slow devices may need much longer.
127If the
128.Dv SCSI_DELAY
129isn't specified, it defaults to 2 seconds. The minimum allowable value for
130.Dv SCSI_DELAY
131is "100", or 100ms. One special case is that if the
132.Dv SCSI_DELAY
133is set to 0, that will be taken to mean the "lowest possible value." In
134that case, the
135.Dv SCSI_DELAY
136will be reset to 100ms.
137.El
138.Pp
139All devices and the SCSI busses support boot time allocation so that
140an upper number of devices and controllers does not need to be configured;
141.Cd "device da0"
142will suffice for any number of disk drivers.
143.Pp
144The devices are either
145.Em wired
146so they appear as a particular device unit or
147.Em counted
148so that they appear as the next available unused unit.
149.Pp
150To configure a driver in the kernel without wiring down the device use a
151config line similar to
152.Cd "device ch0"
153to include the changer driver.
154.Pp
155To wire down a unit use a config line similar to
156.Cd "device ch1 at scbus0 target 4 unit 0"
157to assign changer 1 as the changer with SCSI ID 4,
158SCSI logical unit 0 on SCSI bus 0.
159Individual scbuses can be wired down to specific controllers with
160a config line similar to
161.Cd "device scbus0 at ahc0"
162which assigns scsi bus 0 to the first unit using the ahc driver.
163For controllers supporting more than one bus,
164the particular bus can be specified as in
165.Cd "device scbus3 at ahc1 bus 1"
166which assigns scbus 1 to the second bus probed on the ahc1 device.
167.Pp
168When you have a mixture of wired down and counted devices then the
169counting begins with the first non-wired down unit for a particular
170type. That is, if you have a disk wired down as
171.Em "device da1" ,
172then the first non-wired disk shall come on line as
173.Em da2 .
174.Sh ADAPTERS
175The system allows common device drivers to work through many different
176types of adapters.
177The adapters take requests from the upper layers and do
178all IO between the
179.Em SCSI
180bus and the system.
181The maximum size of a transfer is governed by the
182adapter.
183Most adapters can transfer 64KB in a single operation, however
184many can transfer larger amounts.
185.Sh TARGET MODE
186Some adapters support
187.Em target mode
188in which the system is capable of operating as a device, responding to
189operations initiated by another system.
190Target mode is supported for
191some adapters, but is not yet complete for this version of the CAM
192.Tn SCSI
193subsystem.
194.Sh FILES
195see other scsi device entries.
196.Sh DIAGNOSTICS
a156c807
SW
197When the kernel is compiled with
198.Cd "options CAMDEBUG" ,
199an XPT_DEBUG CCB can be
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200used to enable various amounts of tracing information on any
201specific device.
202Devices not being traced will not produce trace information.
203There are currently four debugging flags that may be turned on:
204.Bl -tag -width CAM_DEBUG_SUBTRACE
205.It Dv CAM_DEBUG_INFO
206This debugging flag enables general informational printfs for the device
207or devices in question.
208.It Dv CAM_DEBUG_TRACE
209This debugging flag enables function-level command flow tracing. i.e.\&
210kernel printfs will happen at the entrance and exit of various functions.
211.It Dv CAM_DEBUG_SUBTRACE
212This debugging flag enables debugging output internal to various functions.
213.It Dv CAM_DEBUG_CDB
214This debugging flag will cause the kernel to print out all
215.Tn SCSI
216commands sent to a particular device or devices.
217.El
218.Pp
219Some of these flags, most notably
220.Dv CAM_DEBUG_TRACE
221and
222.Dv CAM_DEBUG_SUBTRACE
223will produce kernel printfs in EXTREME numbers. Because of that, they
224aren't especially useful. There aren't many things logged at the
225.Dv CAM_DEBUG_INFO
226level, so it isn't especially useful. The most useful debugging flag is
227the
228.Dv CAM_DEBUG_CDB
229flag. Users can enable debugging from their kernel config file, by using
230the following kernel config options:
231.Bl -tag -width CAM_DEBUG_TARGET
232.It Dv CAMDEBUG
233This enables CAM debugging. Without this option, users will not even be able
234to turn on debugging from userland via
235.Xr camcontrol 8 .
236.It Dv CAM_DEBUG_FLAGS
237This allows the user to set the various debugging flags described above
238in a kernel config file. Flags may be ORed together if the user wishes to
239see printfs for multiple debugging levels.
240.It Dv CAM_DEBUG_BUS
241Specify a bus to debug. To debug all busses, set this to -1.
242.It Dv CAM_DEBUG_TARGET
243Specify a target to debug. To debug all targets, set this to -1.
244.It Dv CAM_DEBUG_LUN
245Specify a lun to debug. To debug all luns, set this to -1.
246.El
247.Pp
248When specifying a bus, target or lun to debug, you
249.Em MUST
250specify all three bus/target/lun options above. Using wildcards, you
251should be able to enable debugging on most anything.
252.Pp
253Users may also enable debugging printfs on the fly, if the
254.Dv CAMDEBUG
255option is their config file, by using the
256.Xr camcontrol 8
257utility. See
258.Xr camcontrol 8
259for details.
260.Sh SEE ALSO
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261.Xr ahc 4 ,
262.Xr bt 4 ,
263.Xr cd 4 ,
264.Xr ch 4 ,
265.Xr da 4 ,
266.Xr pass 4 ,
267.Xr pt 4 ,
268.Xr sa 4 ,
269.Xr xpt 4 ,
270.Xr camcontrol 8
271.Sh HISTORY
272The CAM
273.Tn SCSI
274subsystem first appeared in
275.Fx 3.0 .
276.Sh AUTHORS
277.An -nosplit
278The CAM
279.Tn SCSI
280subsystem was written by
281.An Justin Gibbs
282and
283.An Kenneth Merry .