freebsd/share/examples/lkm/misc

# Copyright (c) 1993 Terrence R. Lambert.
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1.0	Overview

	This is the README file for the sample miscellaneous module
	that mimics the loaded system call.

	A miscellaneous module may be used to load any data or
	program into the kernel that can be made available by
	modifying a table, pointer, or other kernel data to inform
	the kernel that the module should be used instead of the
	previous code/data path.

	Generally, it is assumed that a loadable module is one of
	a set of similar modules (such as a file system or console
	terminal emulation), and that the reference is through a
	table (such as vfssw[]), and that a "special" value is
	assigned to the slots which are allowed to be replaced.
	This is not enforced, so you may use the "miscellaneous"
	module any way you see fit.

	As with the loadable system calls, it may be desirable to
	allow the module loader to replace an *existing* entry to
	try out changes to kernel code without rebuilding and
	booting from the new kernel.


2.0	Directions

	To test the module, do the following:

		cd module
		make load

	A load message (the copyright) will be printed on the console.

		cd ../test
		make load

	The system call prints a message on the console when called.
	This message will be printed when running "make load" in
	the "test" subdirectory.


3.0	Recovering resources

	The miscellaneous module consumes 8 pages of memory when
	loaded; it can be freed up by unloading it.  To unload it,
	type the following from the directory this file is in:

		cd module
		make unload

	The miscellaneous module will be unloaded by name.


4.0	END OF DOCUMENT