CS3 Operating Systems 2013-14, Practical Exercise.

PHASE 2
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Compiling and loading kernel modules
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In your background reading, you should by now have found out about 
the principles of Linux kernel modules. Now you should compile and
install one in your UML system, and make sure it loads.

First, it would be a good idea to skim through the 
Modules-HOWTO
(available at www.tldp.org, of course), and/or
The Linux Kernel Module Programming Guide.

The directory /group/teaching/cs3/os/Modules contains a "Hello World"
module, together with a makefile for compiling it. Under 2.6, the
kernel build procedure should be used for compiling standalone
modules, and the kernel build procedure is a very complex beast.
In this practical, you should be able to get away with trivial changes
to the Makefile I've provided, and not need to understand the build
procedure beyond this.

Copy this directory to a directory in your "shared" VM directory.
In the virtual machine, change to that directory, and type
make
and you should get a compiled module  hello.ko

Now (as root, if you weren't already), do
insmod hello.ko

You should see a message (two, in fact: you will see a warning that
the licence "unspecified" "taints the kernel". This is because our
hello module has not been declared to be a GPL module.)

If you do
lsmod
then you will see that indeed the module is loaded.

To unload the module, you do
rmmod hello
at which you should see another message.

If you now do 
dmesg
you should see the messages at the end, so showing that they were
indeed kernel messages, rather than just things printed to the terminal.

That's it: easy.