1.\" Copyright (c) 1996
2.\" Julian Elischer <julian@FreeBSD.org>. All rights reserved.
3.\"
4.\" Redistribution and use in source and binary forms, with or without
5.\" modification, are permitted provided that the following conditions
6.\" are met:
7.\" 1. Redistributions of source code must retain the above copyright
8.\" notice, this list of conditions and the following disclaimer.
9.\"
10.\" 2. Redistributions in binary form must reproduce the above copyright
11.\" notice, this list of conditions and the following disclaimer in the
12.\" documentation and/or other materials provided with the distribution.
13.\"
14.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24.\" SUCH DAMAGE.
25.\"
26.\" $FreeBSD: head/share/man/man4/scsi.4 117011 2003-06-28 23:53:39Z ru $
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 cd"
37.Cd "device ch"
38.Cd "device da"
39.Cd "device pass"
40.Cd "device pt"
41.Cd "device sa"
42.Cd "device ch"
43.Cd "options CAMDEBUG"
44.Cd "options CAM_DEBUG_BUS=-1"
45.Cd "options CAM_DEBUG_TARGET=-1"
46.Cd "options CAM_DEBUG_LUN=-1"
47.Cd "options CAM_DEBUG_FLAGS=CAM_DEBUG_INFO|CAM_DEBUG_CDB"
48.Cd "options CAM_MAX_HIGHPOWER=4"
49.Cd "options SCSI_NO_SENSE_STRINGS"
50.Cd "options SCSI_NO_OP_STRINGS"
51.Cd "options SCSI_DELAY=8000"
52.Sh DESCRIPTION
53The CAM
54.Tn SCSI
55subsystem provides a uniform and modular system for the implementation
56of drivers to control various
57.Tn SCSI
58devices, and to utilize different
59.Tn SCSI
60host adapters through host adapter drivers.
61When the system probes the
62.Tn SCSI
63busses, it attaches any devices it finds to the appropriate
64drivers.
65The
66.Xr pass 4
67driver, if it is configured in the kernel, will attach to all
68.Tn SCSI
69devices.
70.Sh KERNEL CONFIGURATION
71There are a number of generic kernel configuration options for the
72CAM
73.Tn SCSI
74subsystem:
75.Bl -tag -width SCSI_NO_SENSE_STRINGS
76.It Dv CAMDEBUG
77This option enables the CAM debugging printf code.
78This won't actually
79cause any debugging information to be printed out when included by itself.
80Enabling printouts requires additional configuration.
81See below for details.
82.It Dv "CAM_MAX_HIGHPOWER=4"
83This sets the maximum allowable number of concurrent "high power" commands.
84A "high power" command is a command that takes more electrical power than
85most to complete.
86An example of this (and the only command currently
87tagged as "high power") is the
88.Tn SCSI
89START UNIT command.
90Starting a SCSI disk often takes significantly more
91electrical power than normal operation of the disk.
92This option allows the
93user to specify how many concurrent high power commands may be outstanding
94without overloading the power supply on his computer.
95.It Dv SCSI_NO_SENSE_STRINGS
96This eliminates text descriptions of each
97.Tn SCSI
98Additional Sense Code and Additional Sense Code Qualifier pair.
99Since this
100is a fairly large text database, eliminating it reduces the size of the
101kernel somewhat.
102This is primarily necessary for boot floppies and other
103low disk space or low memory space environments.
104In most cases, though,
105this should be enabled, since it speeds the interpretation of
106.Tn SCSI
107error messages. Don't let the "kernel bloat" zealots get to you -- leave
108the sense descriptions in your kernel!
109.It Dv SCSI_NO_OP_STRINGS
110This disables text descriptions of each
111.Tn SCSI
112opcode.
113This option, like the sense string option above, is primarily
114useful for environments like a boot floppy where kernel size is critical.
115Enabling this option for normal use isn't recommended, since it slows
116debugging of
117.Tn SCSI
118problems.
119.It Dv SCSI_DELAY=8000
120This is the
121.Tn SCSI
122"bus settle delay."
123In CAM, it is specified in
124.Em milliseconds ,
125not seconds like the old
126.Tn SCSI
127layer used to do.
128When the kernel boots, it sends a bus reset to each
129.Tn SCSI
130bus to tell each device to reset itself to a default set of transfer
131negotiations and other settings.
132Most
133.Tn SCSI
134devices need some amount of time to recover from a bus reset.
135Newer disks
136may need as little as 100ms, while old, slow devices may need much longer.
137If the
138.Dv SCSI_DELAY
139isn't specified, it defaults to 2 seconds.
140The minimum allowable value for
141.Dv SCSI_DELAY
142is "100", or 100ms.
143One special case is that if the
144.Dv SCSI_DELAY
145is set to 0, that will be taken to mean the "lowest possible value."
146In that case, the
147.Dv SCSI_DELAY
148will be reset to 100ms.
149.El
150.Pp
151All devices and the SCSI busses support boot time allocation so that
152an upper number of devices and controllers does not need to be configured;
153.Cd "device da0"
154will suffice for any number of disk drivers.
155.Pp
156The devices are either
157.Em wired
158so they appear as a particular device unit or
159.Em counted
160so that they appear as the next available unused unit.
161.Pp
162To configure a driver in the kernel without wiring down the device use a
163config line similar to
164.Cd "device ch0"
165to include the changer driver.
166.Pp
167To wire down a unit use a config line similar to
168.Cd "device ch1 at scbus0 target 4 unit 0"
169to assign changer 1 as the changer with SCSI ID 4,
170SCSI logical unit 0 on SCSI bus 0.
171Individual scbuses can be wired down to specific controllers with
172a config line similar to
173.Cd "device scbus0 at ahc0"
174which assigns scsi bus 0 to the first unit using the ahc driver.
175For controllers supporting more than one bus,
176the particular bus can be specified as in
177.Cd "device scbus3 at ahc1 bus 1"
178which assigns scbus 1 to the second bus probed on the ahc1 device.
179.Pp
180When you have a mixture of wired down and counted devices then the
181counting begins with the first non-wired down unit for a particular
182type.
183That is, if you have a disk wired down as
184.Em "device da1" ,
185then the first non-wired disk shall come on line as
186.Em da2 .
187.Sh ADAPTERS
188The system allows common device drivers to work through many different
189types of adapters.
190The adapters take requests from the upper layers and do
191all IO between the
192.Em SCSI
193bus and the system.
194The maximum size of a transfer is governed by the
195adapter.
196Most adapters can transfer 64KB in a single operation, however
197many can transfer larger amounts.
198.Sh TARGET MODE
199Some adapters support
200.Em target mode
201in which the system is capable of operating as a device, responding to
202operations initiated by another system.
203Target mode is supported for
204some adapters, but is not yet complete for this version of the CAM
205.Tn SCSI
206subsystem.
207.Sh FILES
208see other scsi device entries.
209.Sh DIAGNOSTICS
210When the kernel is compiled with options CAMDEBUG, an XPT_DEBUG CCB can be
211used to enable various amounts of tracing information on any
212specific device.
213Devices not being traced will not produce trace information.
214There are currently four debugging flags that may be turned on:
215.Bl -tag -width CAM_DEBUG_SUBTRACE
216.It Dv CAM_DEBUG_INFO
217This debugging flag enables general informational printfs for the device
218or devices in question.
219.It Dv CAM_DEBUG_TRACE
220This debugging flag enables function-level command flow tracing. i.e.\&
221kernel printfs will happen at the entrance and exit of various functions.
222.It Dv CAM_DEBUG_SUBTRACE
223This debugging flag enables debugging output internal to various functions.
224.It Dv CAM_DEBUG_CDB
225This debugging flag will cause the kernel to print out all
226.Tn SCSI
227commands sent to a particular device or devices.
228.El
229.Pp
230Some of these flags, most notably
231.Dv CAM_DEBUG_TRACE
232and
233.Dv CAM_DEBUG_SUBTRACE
234will produce kernel printfs in EXTREME numbers,
235and because of that, they aren't especially useful.
236There aren't many things logged at the
237.Dv CAM_DEBUG_INFO
238level, so it isn't especially useful.
239The most useful debugging flag is the
240.Dv CAM_DEBUG_CDB
241flag. Users can enable debugging from their kernel config file, by using
242the following kernel config options:
243.Bl -tag -width CAM_DEBUG_TARGET
244.It Dv CAMDEBUG
245This enables CAM debugging.
246Without this option, users will not even be able
247to turn on debugging from userland via
248.Xr camcontrol 8 .
249.It Dv CAM_DEBUG_FLAGS
250This allows the user to set the various debugging flags described above
251in a kernel config file.
252Flags may be ORed together if the user wishes to
253see printfs for multiple debugging levels.
254.It Dv CAM_DEBUG_BUS
255Specify a bus to debug.
256To debug all busses, set this to -1.
257.It Dv CAM_DEBUG_TARGET
258Specify a target to debug.
259To debug all targets, set this to -1.
260.It Dv CAM_DEBUG_LUN
261Specify a lun to debug.
262To debug all luns, set this to -1.
263.El
264.Pp
265When specifying a bus, target or lun to debug, you
266.Em MUST
267specify all three bus/target/lun options above.
268Using wildcards, you
269should be able to enable debugging on most anything.
270.Pp
271Users may also enable debugging printfs on the fly, if the
272.Dv CAMDEBUG
273option is their config file, by using the
274.Xr camcontrol 8
275utility. See
276.Xr camcontrol 8
277for details.
278.Sh SEE ALSO
279.Xr aha 4 ,
280.Xr ahb 4 ,
281.Xr ahc 4 ,
282.Xr bt 4 ,
283.Xr cd 4 ,
284.Xr ch 4 ,
285.Xr da 4 ,
286.Xr pass 4 ,
287.Xr pt 4 ,
288.Xr sa 4 ,
289.Xr xpt 4 ,
290.Xr camcontrol 8
291.Sh HISTORY
292The CAM
293.Tn SCSI
294subsystem first appeared in
295.Fx 3.0 .
296.Sh AUTHORS
297.An -nosplit
298The CAM
299.Tn SCSI
300subsystem was written by
301.An Justin Gibbs
302and
303.An Kenneth Merry .
2.\" Julian Elischer <julian@FreeBSD.org>. All rights reserved.
3.\"
4.\" Redistribution and use in source and binary forms, with or without
5.\" modification, are permitted provided that the following conditions
6.\" are met:
7.\" 1. Redistributions of source code must retain the above copyright
8.\" notice, this list of conditions and the following disclaimer.
9.\"
10.\" 2. Redistributions in binary form must reproduce the above copyright
11.\" notice, this list of conditions and the following disclaimer in the
12.\" documentation and/or other materials provided with the distribution.
13.\"
14.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24.\" SUCH DAMAGE.
25.\"
26.\" $FreeBSD: head/share/man/man4/scsi.4 117011 2003-06-28 23:53:39Z ru $
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 cd"
37.Cd "device ch"
38.Cd "device da"
39.Cd "device pass"
40.Cd "device pt"
41.Cd "device sa"
42.Cd "device ch"
43.Cd "options CAMDEBUG"
44.Cd "options CAM_DEBUG_BUS=-1"
45.Cd "options CAM_DEBUG_TARGET=-1"
46.Cd "options CAM_DEBUG_LUN=-1"
47.Cd "options CAM_DEBUG_FLAGS=CAM_DEBUG_INFO|CAM_DEBUG_CDB"
48.Cd "options CAM_MAX_HIGHPOWER=4"
49.Cd "options SCSI_NO_SENSE_STRINGS"
50.Cd "options SCSI_NO_OP_STRINGS"
51.Cd "options SCSI_DELAY=8000"
52.Sh DESCRIPTION
53The CAM
54.Tn SCSI
55subsystem provides a uniform and modular system for the implementation
56of drivers to control various
57.Tn SCSI
58devices, and to utilize different
59.Tn SCSI
60host adapters through host adapter drivers.
61When the system probes the
62.Tn SCSI
63busses, it attaches any devices it finds to the appropriate
64drivers.
65The
66.Xr pass 4
67driver, if it is configured in the kernel, will attach to all
68.Tn SCSI
69devices.
70.Sh KERNEL CONFIGURATION
71There are a number of generic kernel configuration options for the
72CAM
73.Tn SCSI
74subsystem:
75.Bl -tag -width SCSI_NO_SENSE_STRINGS
76.It Dv CAMDEBUG
77This option enables the CAM debugging printf code.
78This won't actually
79cause any debugging information to be printed out when included by itself.
80Enabling printouts requires additional configuration.
81See below for details.
82.It Dv "CAM_MAX_HIGHPOWER=4"
83This sets the maximum allowable number of concurrent "high power" commands.
84A "high power" command is a command that takes more electrical power than
85most to complete.
86An example of this (and the only command currently
87tagged as "high power") is the
88.Tn SCSI
89START UNIT command.
90Starting a SCSI disk often takes significantly more
91electrical power than normal operation of the disk.
92This option allows the
93user to specify how many concurrent high power commands may be outstanding
94without overloading the power supply on his computer.
95.It Dv SCSI_NO_SENSE_STRINGS
96This eliminates text descriptions of each
97.Tn SCSI
98Additional Sense Code and Additional Sense Code Qualifier pair.
99Since this
100is a fairly large text database, eliminating it reduces the size of the
101kernel somewhat.
102This is primarily necessary for boot floppies and other
103low disk space or low memory space environments.
104In most cases, though,
105this should be enabled, since it speeds the interpretation of
106.Tn SCSI
107error messages. Don't let the "kernel bloat" zealots get to you -- leave
108the sense descriptions in your kernel!
109.It Dv SCSI_NO_OP_STRINGS
110This disables text descriptions of each
111.Tn SCSI
112opcode.
113This option, like the sense string option above, is primarily
114useful for environments like a boot floppy where kernel size is critical.
115Enabling this option for normal use isn't recommended, since it slows
116debugging of
117.Tn SCSI
118problems.
119.It Dv SCSI_DELAY=8000
120This is the
121.Tn SCSI
122"bus settle delay."
123In CAM, it is specified in
124.Em milliseconds ,
125not seconds like the old
126.Tn SCSI
127layer used to do.
128When the kernel boots, it sends a bus reset to each
129.Tn SCSI
130bus to tell each device to reset itself to a default set of transfer
131negotiations and other settings.
132Most
133.Tn SCSI
134devices need some amount of time to recover from a bus reset.
135Newer disks
136may need as little as 100ms, while old, slow devices may need much longer.
137If the
138.Dv SCSI_DELAY
139isn't specified, it defaults to 2 seconds.
140The minimum allowable value for
141.Dv SCSI_DELAY
142is "100", or 100ms.
143One special case is that if the
144.Dv SCSI_DELAY
145is set to 0, that will be taken to mean the "lowest possible value."
146In that case, the
147.Dv SCSI_DELAY
148will be reset to 100ms.
149.El
150.Pp
151All devices and the SCSI busses support boot time allocation so that
152an upper number of devices and controllers does not need to be configured;
153.Cd "device da0"
154will suffice for any number of disk drivers.
155.Pp
156The devices are either
157.Em wired
158so they appear as a particular device unit or
159.Em counted
160so that they appear as the next available unused unit.
161.Pp
162To configure a driver in the kernel without wiring down the device use a
163config line similar to
164.Cd "device ch0"
165to include the changer driver.
166.Pp
167To wire down a unit use a config line similar to
168.Cd "device ch1 at scbus0 target 4 unit 0"
169to assign changer 1 as the changer with SCSI ID 4,
170SCSI logical unit 0 on SCSI bus 0.
171Individual scbuses can be wired down to specific controllers with
172a config line similar to
173.Cd "device scbus0 at ahc0"
174which assigns scsi bus 0 to the first unit using the ahc driver.
175For controllers supporting more than one bus,
176the particular bus can be specified as in
177.Cd "device scbus3 at ahc1 bus 1"
178which assigns scbus 1 to the second bus probed on the ahc1 device.
179.Pp
180When you have a mixture of wired down and counted devices then the
181counting begins with the first non-wired down unit for a particular
182type.
183That is, if you have a disk wired down as
184.Em "device da1" ,
185then the first non-wired disk shall come on line as
186.Em da2 .
187.Sh ADAPTERS
188The system allows common device drivers to work through many different
189types of adapters.
190The adapters take requests from the upper layers and do
191all IO between the
192.Em SCSI
193bus and the system.
194The maximum size of a transfer is governed by the
195adapter.
196Most adapters can transfer 64KB in a single operation, however
197many can transfer larger amounts.
198.Sh TARGET MODE
199Some adapters support
200.Em target mode
201in which the system is capable of operating as a device, responding to
202operations initiated by another system.
203Target mode is supported for
204some adapters, but is not yet complete for this version of the CAM
205.Tn SCSI
206subsystem.
207.Sh FILES
208see other scsi device entries.
209.Sh DIAGNOSTICS
210When the kernel is compiled with options CAMDEBUG, an XPT_DEBUG CCB can be
211used to enable various amounts of tracing information on any
212specific device.
213Devices not being traced will not produce trace information.
214There are currently four debugging flags that may be turned on:
215.Bl -tag -width CAM_DEBUG_SUBTRACE
216.It Dv CAM_DEBUG_INFO
217This debugging flag enables general informational printfs for the device
218or devices in question.
219.It Dv CAM_DEBUG_TRACE
220This debugging flag enables function-level command flow tracing. i.e.\&
221kernel printfs will happen at the entrance and exit of various functions.
222.It Dv CAM_DEBUG_SUBTRACE
223This debugging flag enables debugging output internal to various functions.
224.It Dv CAM_DEBUG_CDB
225This debugging flag will cause the kernel to print out all
226.Tn SCSI
227commands sent to a particular device or devices.
228.El
229.Pp
230Some of these flags, most notably
231.Dv CAM_DEBUG_TRACE
232and
233.Dv CAM_DEBUG_SUBTRACE
234will produce kernel printfs in EXTREME numbers,
235and because of that, they aren't especially useful.
236There aren't many things logged at the
237.Dv CAM_DEBUG_INFO
238level, so it isn't especially useful.
239The most useful debugging flag is the
240.Dv CAM_DEBUG_CDB
241flag. Users can enable debugging from their kernel config file, by using
242the following kernel config options:
243.Bl -tag -width CAM_DEBUG_TARGET
244.It Dv CAMDEBUG
245This enables CAM debugging.
246Without this option, users will not even be able
247to turn on debugging from userland via
248.Xr camcontrol 8 .
249.It Dv CAM_DEBUG_FLAGS
250This allows the user to set the various debugging flags described above
251in a kernel config file.
252Flags may be ORed together if the user wishes to
253see printfs for multiple debugging levels.
254.It Dv CAM_DEBUG_BUS
255Specify a bus to debug.
256To debug all busses, set this to -1.
257.It Dv CAM_DEBUG_TARGET
258Specify a target to debug.
259To debug all targets, set this to -1.
260.It Dv CAM_DEBUG_LUN
261Specify a lun to debug.
262To debug all luns, set this to -1.
263.El
264.Pp
265When specifying a bus, target or lun to debug, you
266.Em MUST
267specify all three bus/target/lun options above.
268Using wildcards, you
269should be able to enable debugging on most anything.
270.Pp
271Users may also enable debugging printfs on the fly, if the
272.Dv CAMDEBUG
273option is their config file, by using the
274.Xr camcontrol 8
275utility. See
276.Xr camcontrol 8
277for details.
278.Sh SEE ALSO
279.Xr aha 4 ,
280.Xr ahb 4 ,
281.Xr ahc 4 ,
282.Xr bt 4 ,
283.Xr cd 4 ,
284.Xr ch 4 ,
285.Xr da 4 ,
286.Xr pass 4 ,
287.Xr pt 4 ,
288.Xr sa 4 ,
289.Xr xpt 4 ,
290.Xr camcontrol 8
291.Sh HISTORY
292The CAM
293.Tn SCSI
294subsystem first appeared in
295.Fx 3.0 .
296.Sh AUTHORS
297.An -nosplit
298The CAM
299.Tn SCSI
300subsystem was written by
301.An Justin Gibbs
302and
303.An Kenneth Merry .