240 lines
8.6 KiB
Perl
240 lines
8.6 KiB
Perl
.\" Copyright (c) 1983, 1993
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.\" The Regents of the University of California. 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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.\" 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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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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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.\" @(#)6.t 8.1 (Berkeley) 6/8/93
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.\"
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.\".ds RH "Adding New Devices
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.ne 2i
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.NH
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ADDING NEW SYSTEM SOFTWARE
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.PP
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This section is not for the novice, it describes
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some of the inner workings of the configuration process as
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well as the pertinent parts of the system autoconfiguration process.
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It is intended to give
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those people who intend to install new device drivers and/or
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other system facilities sufficient information to do so in the
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manner which will allow others to easily share the changes.
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.PP
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This section is broken into four parts:
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.IP \(bu 3
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general guidelines to be followed in modifying system code,
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.IP \(bu 3
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how to add non-standard system facilities to 4.4BSD,
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.IP \(bu 3
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how to add a device driver to 4.4BSD, and
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.NH 2
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Modifying system code
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.PP
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If you wish to make site-specific modifications to the system
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it is best to bracket them with
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.DS
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#ifdef SITENAME
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\&...
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#endif
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.DE
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to allow your source to be easily distributed to others, and
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also to simplify \fIdiff\fP\|(1) listings. If you choose not
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to use a source code control system (e.g. SCCS, RCS), and
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perhaps even if you do, it is
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recommended that you save the old code with something
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of the form:
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.DS
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#ifndef SITENAME
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\&...
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#endif
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.DE
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We try to isolate our site-dependent code in individual files
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which may be configured with pseudo-device specifications.
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.PP
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Indicate machine-specific code with ``#ifdef vax'' (or other machine,
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as appropriate).
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4.4BSD underwent extensive work to make it extremely portable to
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machines with similar architectures\- you may someday find
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yourself trying to use a single copy of the source code on
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multiple machines.
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.NH 2
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Adding non-standard system facilities
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.PP
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This section considers the work needed to augment
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.IR config 's
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data base files for non-standard system facilities.
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.I Config
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uses a set of files that list the source modules that may be required
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when building a system.
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The data bases are taken from the directory in which
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.I config
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is run, normally /sys/conf.
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Three such files may be used:
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.IR files ,
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.IR files .machine,
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and
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.IR files .ident.
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The first is common to all systems,
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the second contains files unique to a single machine type,
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and the third is an optional list of modules for use on a specific machine.
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This last file may override specifications in the first two.
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The format of the
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.I files
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file has grown somewhat complex over time. Entries are normally of
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the form
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.IP
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.nf
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.DT
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\fIdir/source.c\fP \fItype\fP \fIoption-list\fP \fImodifiers\fP
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.LP
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for example,
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.IP
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.nf
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.DT
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\fIvaxuba/foo.c\fP \fBoptional\fP foo \fBdevice-driver\fP
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.LP
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The
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.I type
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is one of
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.B standard
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or
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.BR optional .
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Files marked as standard are included in all system configurations.
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Optional file specifications include a list of one or more system
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options that together require the inclusion of this module.
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The options in the list may be either names of devices that may
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be in the configuration file,
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or the names of system options that may be defined.
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An optional file may be listed multiple times with different options;
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if all of the options for any of the entries are satisfied,
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the module is included.
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.PP
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If a file is specified as a
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.IR device-driver ,
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any special compilation options for device drivers will be invoked.
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On the VAX this results in the use of the
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.B \-i
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option for the C optimizer. This is required when pointer references
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are made to memory locations in the VAX I/O address space.
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.PP
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Two other optional keywords modify the usage of the file.
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.I Config
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understands that certain files are used especially for
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kernel profiling. These files are indicated in the
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.I files
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files with a
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.I profiling-routine
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keyword. For example, the current profiling subroutines
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are sequestered off in a separate file with the following
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entry:
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.IP
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.nf
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.DT
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\fIsys/subr_mcount.c\fP \fBoptional\fP \fBprofiling-routine\fP
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.fi
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.LP
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The
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.I profiling-routine
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keyword forces
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.I config
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not to compile the source file with the
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.B \-pg
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option.
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.PP
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The second keyword which can be of use is the
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.I config-dependent
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keyword. This causes
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.I config
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to compile the indicated module with the global configuration
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parameters. This allows certain modules, such as
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.I machdep.c
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to size system data structures based on the maximum number
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of users configured for the system.
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.NH 2
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Adding device drivers to 4.4BSD
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.PP
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The I/O system and
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.I config
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have been designed to easily allow new device support to be added.
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The system source directories are organized as follows:
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.DS
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.TS
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lw(1.0i) l.
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/sys/h machine independent include files
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/sys/sys machine-independent system source files
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/sys/conf site configuration files and basic templates
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/sys/net network-protocol-independent, but network-related code
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/sys/netinet DARPA Internet code
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/sys/netimp IMP support code
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/sys/netns Xerox NS code
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/sys/vax VAX-specific mainline code
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/sys/vaxif VAX network interface code
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/sys/vaxmba VAX MASSBUS device drivers and related code
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/sys/vaxuba VAX UNIBUS device drivers and related code
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.TE
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.DE
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.PP
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Existing block and character device drivers for the VAX
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reside in ``/sys/vax'', ``/sys/vaxmba'', and ``/sys/vaxuba''. Network
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interface drivers reside in ``/sys/vaxif''. Any new device
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drivers should be placed in the appropriate source code directory
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and named so as not to conflict with existing devices.
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Normally, definitions for things like device registers are placed in
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a separate file in the same directory. For example, the ``dh''
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device driver is named ``dh.c'' and its associated include file is
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named ``dhreg.h''.
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.PP
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Once the source for the device driver has been placed in a directory,
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the file ``/sys/conf/files.machine'', and possibly
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``/sys/conf/devices.machine'' should be modified. The
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.I files
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files in the conf directory contain a line for each C source or binary-only
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file in the system. Those files which are machine independent are
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located in ``/sys/conf/files,'' while machine specific files
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are in ``/sys/conf/files.machine.'' The ``devices.machine'' file
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is used to map device names to major block device numbers. If the device
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driver being added provides support for a new disk
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you will want to modify this file (the format is obvious).
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.PP
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In addition to including the driver in the
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.I files
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file, it must also be added to the device configuration tables. These
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are located in ``/sys/vax/conf.c'', or similar for machines other than
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the VAX. If you don't understand what to add to this file, you should
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study an entry for an existing driver.
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Remember that the position in the
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device table specifies the major device number.
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The block major number is needed in the ``devices.machine'' file
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if the device is a disk.
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.PP
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With the configuration information in place, your configuration
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file appropriately modified, and a system reconfigured and rebooted
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you should incorporate the shell commands needed to install the special
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files in the file system to the file ``/dev/MAKEDEV'' or
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``/dev/MAKEDEV.local''. This is discussed in the document ``Installing
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and Operating 4.4BSD''.
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