1.Dd August 27, 1993
2.Dt SD 4
3.Os FreeBSD
4.Sh NAME
5.Nm scsi
6.Nd scsi system
7.Sh SYNOPSIS
8.Nm controller scbus0
9.Nm device cd0
10.Nm device ch0
11.Nm disk sd0
12.Nm tape st0
13.Nm device ch1 at scbus0 target 4 unit 0
14.Sh DESCRIPTION
15The
16.Em scsi
17system provides a uniform and modular system for the implementation
18of drivers to control various scsi devices, and to utilise different
19scsi host adapters through host adapter drivers. When the system probes the
20.Em SCSI
21busses, it attaches any devices it finds to the appropriate
22drivers. If no driver seems appropriate, then it attaches the device to the
23uk (unknown) driver so that user level scsi ioctls may
24still be performed against the device.
25.Sh KERNEL CONFIGURATION
26The option SCSIDEBUG enables the debug ioctl.
27.Pp
28All devices and the SCSI busses support boot time allocation so that
29an upper number of devices and controllers does not need to be configured;
30.Em "device sd0"
31will suffice for any number of disk drivers.
32.Pp
33The devices are either
34.Em wired
35so they appear as a particular device unit or
36.Em counted
37so that they appear as the next available unused unit.
38.Pp
39To configure a driver in the kernel without wiring down the device use a
40config line similar to
41.Em "device ch0"
42to include the changer driver.
43.Pp
44To wire down a
45unit use a config line similar to
46.Em "device ch1 at scbus0 target 4 unit 0"
47to assign changer 1 as the changer with SCSI ID 4 SCSI logical unit 0 on
48SCSI bus 0.
49.Pp
50When you have a mixture of wired down and counted devices then the
51counting begins with the first non-wired down unit for a particular
52type. That is, if you have a disk wired down as
53.Em "disk sd1" ,
54then the first non-wired disk shall come on line as
55.Em sd2 .
56.Sh IOCTLS
57There are a number of ioctls that work on any
58.Em SCSI
59device. They are defined in
60.Em sys/scsiio.h
61and can be applied against any scsi device that permits them.
62For the tape, it must be applied against the control
63device. See the manual page for each device type for more information about
64how generic scsi ioctls may be applied to a specific device.
65.Bl -tag -width DIOCSDINFO____
66.It Dv SCIOCRESET*
67reset a device.
68.It Dv SCIOCDEBUG
69Turn on debugging.. All scsi operations originating from this device's driver
70will be traced to the console, along with other information. Debugging is
71controlled by four bits, described in the header file. If no debugging is
72configured into the kernel, debugging will have no effect.
73.Em SCSI
74debugging is controlled by the configuration option
75.Em SCSIDEBUG.
76.It Dv SCIOCCOMMAND
77Take a scsi command and data from a user process and apply them to the scsi
78device. Return all status information and return data to the process. The
79ioctl will return a successful status even if the device rejected the
80command. As all status is returned to the user, it is up to the user
81process to examine this information to decide the success of the command.
82.It Dv SCIOCREPROBE
83Ask the system to probe the scsi busses for any new devices. If it finds
84any, they will be attached to the appropriate drivers. The search can be
85narrowed to a specific bus, target or lun. The new device may or may not
86be related to the device on which the ioctl was performed.
87.It Dv SCIOCIDENTIFY
88Ask the driver what it's bus, target and lun are.
89.It Dv SCIOCDECONFIG
90Ask the device to dissappear. This may not happen if the device is in use.
91.El
92.Sh NOTES
93the generic scsi part of the system is still being mapped out.
94Watch this space for changes.
95.Pp
96 A device by the name of su (scsi_user)
97(e.g su0-0-0) will map bus, target and lun to minor numbers. I have not
98yet decided yet whether this device will be able to open a device that is
99already controlled by an explicit driver.
100.Sh ADAPTERS
101The system allows common device drivers to work through many different
102types of adapters. The adapters take requests from the upper layers and do
103all IO between the
104.Em SCSI
105bus and the system. The maximum size of a transfer is governed by the
106adapter. Most adapters can transfer 64KB in a single operation, however
107many can transfer larger amounts.
108.Sh TARGET MODE
109Some adapters support
110.Em Target mode
111in which the system is capable of operating as a device, responding to
112operations initioated by another system. Target mode will be supported for
113some adapters, but is not yet complete for this version of the scsi system.
114.Sh FILES
115see other scsi device entries.
116.Sh DIAGNOSTICS
117When the kernel is compiled with option SCSIDEBUG, the SCIOCDEBUG ioctl
118can be used to enable various amounts of tracing information on any
119specific device. Devices not being traced will not produce trace information.
120The four bits that make up the debug level, each control certain types
121of debugging information.
122.Bl -tag -width THIS_WIDE_PLEASE
123.It Dv Bit 0
124Bit 0 shows all scsi bus operations including scsi commands,
125error information and the first 48 bytes of any data transferred.
126.It Dv Bit 1
127Bit 1 shows routines called.
128.It Dv Bit 2
129Bit 2 shows information about what branches are taken and often some
130of the return values of functions.
131.It Dv Bit 3
132Bit 3 shows more detailed information including DMA scatter-gather logs.
133.El
134.Sh SEE ALSO
135.Xr ch 4
136.Xr cd 4
137.Xr sd 4
138.Xr st 4
139.Xr uk 4
140.Xr su 4
141.Xr aha 4
142.Xr ahb 4
143.Xr bt 4
144.Xr uha 4
145.Sh HISTORY
146This
147.Nm
148system appeared in MACH 2.5 at TRW.
149
2.Dt SD 4
3.Os FreeBSD
4.Sh NAME
5.Nm scsi
6.Nd scsi system
7.Sh SYNOPSIS
8.Nm controller scbus0
9.Nm device cd0
10.Nm device ch0
11.Nm disk sd0
12.Nm tape st0
13.Nm device ch1 at scbus0 target 4 unit 0
14.Sh DESCRIPTION
15The
16.Em scsi
17system provides a uniform and modular system for the implementation
18of drivers to control various scsi devices, and to utilise different
19scsi host adapters through host adapter drivers. When the system probes the
20.Em SCSI
21busses, it attaches any devices it finds to the appropriate
22drivers. If no driver seems appropriate, then it attaches the device to the
23uk (unknown) driver so that user level scsi ioctls may
24still be performed against the device.
25.Sh KERNEL CONFIGURATION
26The option SCSIDEBUG enables the debug ioctl.
27.Pp
28All devices and the SCSI busses support boot time allocation so that
29an upper number of devices and controllers does not need to be configured;
30.Em "device sd0"
31will suffice for any number of disk drivers.
32.Pp
33The devices are either
34.Em wired
35so they appear as a particular device unit or
36.Em counted
37so that they appear as the next available unused unit.
38.Pp
39To configure a driver in the kernel without wiring down the device use a
40config line similar to
41.Em "device ch0"
42to include the changer driver.
43.Pp
44To wire down a
45unit use a config line similar to
46.Em "device ch1 at scbus0 target 4 unit 0"
47to assign changer 1 as the changer with SCSI ID 4 SCSI logical unit 0 on
48SCSI bus 0.
49.Pp
50When you have a mixture of wired down and counted devices then the
51counting begins with the first non-wired down unit for a particular
52type. That is, if you have a disk wired down as
53.Em "disk sd1" ,
54then the first non-wired disk shall come on line as
55.Em sd2 .
56.Sh IOCTLS
57There are a number of ioctls that work on any
58.Em SCSI
59device. They are defined in
60.Em sys/scsiio.h
61and can be applied against any scsi device that permits them.
62For the tape, it must be applied against the control
63device. See the manual page for each device type for more information about
64how generic scsi ioctls may be applied to a specific device.
65.Bl -tag -width DIOCSDINFO____
66.It Dv SCIOCRESET*
67reset a device.
68.It Dv SCIOCDEBUG
69Turn on debugging.. All scsi operations originating from this device's driver
70will be traced to the console, along with other information. Debugging is
71controlled by four bits, described in the header file. If no debugging is
72configured into the kernel, debugging will have no effect.
73.Em SCSI
74debugging is controlled by the configuration option
75.Em SCSIDEBUG.
76.It Dv SCIOCCOMMAND
77Take a scsi command and data from a user process and apply them to the scsi
78device. Return all status information and return data to the process. The
79ioctl will return a successful status even if the device rejected the
80command. As all status is returned to the user, it is up to the user
81process to examine this information to decide the success of the command.
82.It Dv SCIOCREPROBE
83Ask the system to probe the scsi busses for any new devices. If it finds
84any, they will be attached to the appropriate drivers. The search can be
85narrowed to a specific bus, target or lun. The new device may or may not
86be related to the device on which the ioctl was performed.
87.It Dv SCIOCIDENTIFY
88Ask the driver what it's bus, target and lun are.
89.It Dv SCIOCDECONFIG
90Ask the device to dissappear. This may not happen if the device is in use.
91.El
92.Sh NOTES
93the generic scsi part of the system is still being mapped out.
94Watch this space for changes.
95.Pp
96 A device by the name of su (scsi_user)
97(e.g su0-0-0) will map bus, target and lun to minor numbers. I have not
98yet decided yet whether this device will be able to open a device that is
99already controlled by an explicit driver.
100.Sh ADAPTERS
101The system allows common device drivers to work through many different
102types of adapters. The adapters take requests from the upper layers and do
103all IO between the
104.Em SCSI
105bus and the system. The maximum size of a transfer is governed by the
106adapter. Most adapters can transfer 64KB in a single operation, however
107many can transfer larger amounts.
108.Sh TARGET MODE
109Some adapters support
110.Em Target mode
111in which the system is capable of operating as a device, responding to
112operations initioated by another system. Target mode will be supported for
113some adapters, but is not yet complete for this version of the scsi system.
114.Sh FILES
115see other scsi device entries.
116.Sh DIAGNOSTICS
117When the kernel is compiled with option SCSIDEBUG, the SCIOCDEBUG ioctl
118can be used to enable various amounts of tracing information on any
119specific device. Devices not being traced will not produce trace information.
120The four bits that make up the debug level, each control certain types
121of debugging information.
122.Bl -tag -width THIS_WIDE_PLEASE
123.It Dv Bit 0
124Bit 0 shows all scsi bus operations including scsi commands,
125error information and the first 48 bytes of any data transferred.
126.It Dv Bit 1
127Bit 1 shows routines called.
128.It Dv Bit 2
129Bit 2 shows information about what branches are taken and often some
130of the return values of functions.
131.It Dv Bit 3
132Bit 3 shows more detailed information including DMA scatter-gather logs.
133.El
134.Sh SEE ALSO
135.Xr ch 4
136.Xr cd 4
137.Xr sd 4
138.Xr st 4
139.Xr uk 4
140.Xr su 4
141.Xr aha 4
142.Xr ahb 4
143.Xr bt 4
144.Xr uha 4
145.Sh HISTORY
146This
147.Nm
148system appeared in MACH 2.5 at TRW.
149