148 lines
4.6 KiB
Groff
148 lines
4.6 KiB
Groff
.\" $NetBSD: lkm.4,v 1.7 1999/03/16 01:19:16 garbled Exp $
|
|
.\"
|
|
.\" Copyright (c) 1993 Christopher G. Demetriou
|
|
.\" All rights reserved.
|
|
.\"
|
|
.\" Redistribution and use in source and binary forms, with or without
|
|
.\" modification, are permitted provided that the following conditions
|
|
.\" are met:
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer.
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
.\" 3. The name of the author may not be used to endorse or promote products
|
|
.\" derived from this software without specific prior written permission
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
|
|
.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
|
|
.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
|
|
.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
|
|
.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
|
|
.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
|
|
.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
|
|
.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
|
|
.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
|
|
.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
|
|
.\"
|
|
.Dd September 4, 1993
|
|
.Dt LKM 4
|
|
.Os
|
|
.Sh NAME
|
|
.Nm lkm
|
|
.Nd Loadable Kernel Modules interface
|
|
.Sh SYNOPSIS
|
|
.Cd "options LKM"
|
|
.Sh DESCRIPTION
|
|
Loadable kernel modules allow the system administrator to
|
|
dynamically add and remove functionality from a running system.
|
|
This ability also helps software developers to develop
|
|
new parts of the kernel without constantly rebooting to
|
|
test their changes.
|
|
.Pp
|
|
Various types of modules can be loaded into the sytem.
|
|
There are several defined module types, listed below, which can
|
|
be added to the system in a predefined way. In addition, there
|
|
is a generic type, for which the module itself handles loading and
|
|
unloading.
|
|
.Pp
|
|
The
|
|
.Nm
|
|
interface is used by performing
|
|
.Xr ioctl 2
|
|
calls on the
|
|
.Pa /dev/lkm
|
|
device. Normally all operations involving
|
|
Loadable Kernel Modules are handled by the
|
|
.Xr modload 8 ,
|
|
.Xr modunload 8 ,
|
|
and
|
|
.Xr modstat 8
|
|
programs. Users should never have to interact with
|
|
.Pa /dev/lkm
|
|
directly.
|
|
.Sh "MODULE TYPES"
|
|
.Bl -tag -width indent
|
|
.It System Call modules
|
|
System calls may be replaced by loading
|
|
new ones via the
|
|
.Nm
|
|
interface. All system calls may be
|
|
replaced, but special care should
|
|
be taken with the
|
|
.Xr ioctl 2
|
|
system call, as it is used to load and
|
|
unload modules.
|
|
.Pp
|
|
When a system call module is unloaded,
|
|
the system call which
|
|
was replaced by the loadable module
|
|
is returned to its rightful place
|
|
in the system call table.
|
|
.It Virtual File System modules
|
|
Virtual file systems may be added
|
|
via the
|
|
.Nm
|
|
interface. At this time, only
|
|
file systems which are already
|
|
known to the system can be added,
|
|
because of the way the
|
|
.Xr mount 2
|
|
system call is implemented.
|
|
.It Device Driver modules
|
|
New block and character device
|
|
drivers may be loaded into the system with
|
|
.Nm LKM .
|
|
The major problem with loading
|
|
a device driver is that the driver's
|
|
device nodes must be exist for the
|
|
devices to be accessed. They are usually
|
|
created by instructing
|
|
.Xr modload 8
|
|
to run an appropriate program when
|
|
the driver has been successfully loaded.
|
|
.It Execution Interpreters
|
|
Execution interpreters allow
|
|
the loading and execution of
|
|
binaries which are normally not
|
|
usable by the operating system.
|
|
.It Miscellaneous modules
|
|
Miscellaneous modules are modules
|
|
for which there are not currently
|
|
well-defined or well-used interfaces
|
|
for extension. The user is expected
|
|
to write their own loader to manipulate
|
|
whatever kernel data structures necessary
|
|
to enable and disable the new module
|
|
when it is loaded and unloaded.
|
|
.El
|
|
.Sh FILES
|
|
.Bl -tag -width /usr/include/sys/lkm.h -compact
|
|
.It Pa /dev/lkm
|
|
.Nm
|
|
interface device
|
|
.It Pa /usr/include/sys/lkm.h
|
|
file containing defitions of module types
|
|
.It Pa /usr/share/lkm
|
|
example source code implementing several of the modules types
|
|
.El
|
|
.Sh SEE ALSO
|
|
.Xr modload 8 ,
|
|
.Xr modunload 8 ,
|
|
.Xr modstat 8
|
|
.Sh HISTORY
|
|
The
|
|
.Nm
|
|
facility was designed to be similar in functionality
|
|
to the loadable kernel modules facility provided by
|
|
.Tn "SunOS 4.1.3" .
|
|
.Sh AUTHOR
|
|
.Bl -tag
|
|
Terrence R. Lambert, terry@cs.weber.edu
|
|
.El
|
|
.Sh BUGS
|
|
Loading a bogus module is likely to kill your machine.
|
|
.Pp
|
|
Loadable streams modules should and will be implemented
|
|
when a streams implementation is written.
|