kmod-tutorial/docs at master · dillonhicks/kmod-tutorial · GitHub

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README
======

This directory contains examples of kernel modules that implement
certain interfaces we have found to be essential for kernel driver
driver (pseudo or otherwise).

Specifically the interfaces we wish to show are the:

- procfs

    - helloworld
    - tabularasa

- ioctrl

    - helloworld
    - tabularasa
    - blankslate

- timers
- sysfs

    - blankslate

- kernel signals

- kernel parameters

    - helloworld


- Bootstrapping for a module is a little more lengthy than most
  programming.

- To create a module at all there will need to be a minimum of the
  following things:

    - the module:

        - source (.c)
	- header (.h)
	- Makefile

    - the user side library as an api
    - a user level test program
    - And typically some datastreams post processing


Examples
********

**tabularasa**

- It is a little more complex than the simplest possible module as it
  incorporates the minimal about of stuff requried to make a non
  trivial module.

- It demonstrates:

    - Setting module level variable via IOCTL

        - protecting said variable via a mutex

    - Reading the variable from the procfs

    - How to use procfs (albeit simply). Prints "Hello World! I am
      <tabularasa_module_name>" to ``/proc/tabularasa`` where
      tabularasa_module_name is a module level variable::

        $ cat /proc/tabularasa
	Hello World! I am tabularasa

- To execute this example first you must build the module::

    $ cd <kr>/examples/kmods/tabularasa/kmods
    $ make module

- Install the module::

    $ make install

    - This will run a :samp:`sudo insmod tabularasa`

- Make the user library and program::

    $ make prog


    - This will make a build directory under the tabularasa directory.

    - Contains the compiled *truser* program and *libtabularasa* library


- Execute the user program::

    $ make run
    Hello World! I am tabularasa
    Hello World! I am skynet
    Hello World! I am john-conner
    Hello World! I am t-800
    Hello World! I am terminator