1130b656e5
This will make a number of things easier in the future, as well as (finally!) avoiding the Id-smashing problem which has plagued developers for so long. Boy, I'm glad we're not using sup anymore. This update would have been insane otherwise.
185 lines
7.1 KiB
Groff
185 lines
7.1 KiB
Groff
.\" $FreeBSD$
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.\" Copyright (c) 1996
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.\" Julian Elischer <julian@freebsd.org>. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\"
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.Dd August 27, 1993
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.Dt SD 4
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.Os FreeBSD
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.Sh NAME
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.Nm scsi
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.Nd scsi system
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.Sh SYNOPSIS
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.Nm controller scbus0
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.Nm controller scbus1 at ahc0
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.Nm controller scbus3 at ahc1 bus 0
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.Nm controller scbus2 at ahc1 bus 1
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.Nm device cd0
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.Nm device ch0
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.Nm disk sd0
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.Nm tape st0
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.Nm device ch1 at scbus0 target 4 unit 0
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.Sh DESCRIPTION
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The
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.Em scsi
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system provides a uniform and modular system for the implementation
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of drivers to control various scsi devices, and to utilize different
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scsi host adapters through host adapter drivers. When the system probes the
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.Em SCSI
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busses, it attaches any devices it finds to the appropriate
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drivers. If no driver seems appropriate, then it attaches the device to the
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uk (unknown) driver so that user level scsi ioctls may
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still be performed against the device.
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.Sh KERNEL CONFIGURATION
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The option SCSIDEBUG enables the debug ioctl.
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.Pp
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All devices and the SCSI busses support boot time allocation so that
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an upper number of devices and controllers does not need to be configured;
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.Em "device sd0"
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will suffice for any number of disk drivers.
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.Pp
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The devices are either
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.Em wired
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so they appear as a particular device unit or
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.Em counted
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so that they appear as the next available unused unit.
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.Pp
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To configure a driver in the kernel without wiring down the device use a
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config line similar to
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.Em "device ch0"
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to include the changer driver.
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.Pp
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To wire down a unit use a config line similar to
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.Em "device ch1 at scbus0 target 4 unit 0"
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to assign changer 1 as the changer with SCSI ID 4,
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SCSI logical unit 0 on SCSI bus 0.
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Individual scbuses can be wired down to specific controllers with
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a config line similar to
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.Em "controller scbus0 at ahc0"
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which assigns scsi bus 0 to the first unit using the ahc driver.
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For controllers supporting more than one bus,
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the particular bus can be specified as in
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.Em "controller scbus3 at ahc1 bus 1"
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which assigns scbus 1 to the second bus probed on the ahc1 device.
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.Pp
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When you have a mixture of wired down and counted devices then the
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counting begins with the first non-wired down unit for a particular
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type. That is, if you have a disk wired down as
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.Em "disk sd1" ,
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then the first non-wired disk shall come on line as
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.Em sd2 .
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.Sh IOCTLS
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There are a number of ioctls that work on any
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.Em SCSI
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device. They are defined in
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.Em sys/scsiio.h
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and can be applied against any scsi device that permits them.
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For the tape, it must be applied against the control
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device. See the manual page for each device type for more information about
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how generic scsi ioctls may be applied to a specific device.
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.Bl -tag -width DIOCSDINFO____
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.It Dv SCIOCRESET*
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reset a device.
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.It Dv SCIOCDEBUG
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Turn on debugging.. All scsi operations originating from this device's driver
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will be traced to the console, along with other information. Debugging is
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controlled by four bits, described in the header file. If no debugging is
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configured into the kernel, debugging will have no effect.
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.Em SCSI
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debugging is controlled by the configuration option
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.Em SCSIDEBUG.
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.It Dv SCIOCCOMMAND
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Take a scsi command and data from a user process and apply them to the scsi
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device. Return all status information and return data to the process. The
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ioctl will return a successful status even if the device rejected the
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command. As all status is returned to the user, it is up to the user
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process to examine this information to decide the success of the command.
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.It Dv SCIOCREPROBE
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Ask the system to probe the scsi busses for any new devices. If it finds
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any, they will be attached to the appropriate drivers. The search can be
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narrowed to a specific bus, target or lun. The new device may or may not
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be related to the device on which the ioctl was performed.
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.It Dv SCIOCIDENTIFY
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Ask the driver what it's bus, target and lun are.
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.It Dv SCIOCDECONFIG
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Ask the device to disappear. This may not happen if the device is in use.
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.El
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.Sh NOTES
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the generic scsi part of the system is still being mapped out.
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Watch this space for changes.
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.Pp
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A device by the name of su (scsi_user)
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(e.g su0-0-0) will map bus, target and lun to minor numbers. I have not
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yet decided yet whether this device will be able to open a device that is
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already controlled by an explicit driver.
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.Sh ADAPTERS
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The system allows common device drivers to work through many different
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types of adapters. The adapters take requests from the upper layers and do
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all IO between the
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.Em SCSI
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bus and the system. The maximum size of a transfer is governed by the
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adapter. Most adapters can transfer 64KB in a single operation, however
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many can transfer larger amounts.
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.Sh TARGET MODE
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Some adapters support
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.Em Target mode
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in which the system is capable of operating as a device, responding to
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operations initiated by another system. Target mode will be supported for
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some adapters, but is not yet complete for this version of the scsi system.
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.Sh FILES
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see other scsi device entries.
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.Sh DIAGNOSTICS
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When the kernel is compiled with option SCSIDEBUG, the SCIOCDEBUG ioctl
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can be used to enable various amounts of tracing information on any
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specific device. Devices not being traced will not produce trace information.
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The four bits that make up the debug level, each control certain types
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of debugging information.
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.Bl -tag -width THIS_WIDE_PLEASE
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.It Dv Bit 0
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Bit 0 shows all scsi bus operations including scsi commands,
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error information and the first 48 bytes of any data transferred.
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.It Dv Bit 1
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Bit 1 shows routines called.
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.It Dv Bit 2
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Bit 2 shows information about what branches are taken and often some
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of the return values of functions.
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.It Dv Bit 3
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Bit 3 shows more detailed information including DMA scatter-gather logs.
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.El
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.Sh SEE ALSO
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.Xr aha 4 ,
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.Xr ahb 4 ,
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.Xr bt 4 ,
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.Xr cd 4 ,
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.Xr ch 4 ,
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.Xr sd 4 ,
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.Xr st 4 ,
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.Xr su 4 ,
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.Xr uha 4 ,
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.Xr uk 4
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.Sh HISTORY
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This
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.Nm
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system appeared in MACH 2.5 at TRW.
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