This document discusses studying the Linux kernel and kernel modules. It provides background on the Linux kernel, describing its initial development in 1991 and key updates and versions released through 2015. It also describes kernel modules and their uses. The objectives are to develop a reasonably sized dynamically loadable kernel module, pass command line arguments to a module, build modules for a precompiled kernel, and implement a module. The procedures and coding required are also outlined.

1. Sumbitted by, Guided by,
R.Hanan Raj , Mrs.Tamilselvi,M.E,
M.E(CSE), Assitant Professer,
ARJ CET. Dept of CSE,
ARJ CET.
STUDY OF LINUX KERNEL
AND KERNEL MODULES
module.

2. AIM:
To study of linux kernel and kernel modules.
OBJECTIVE:
Linux kernel:
The Linux kernel is a Unix-like computer
operating system kernel. TheLinux kernel is a
widely used operating system kernel world-wide .
Kernel module:
A loadable kernel module (or LKM) is
object file that contains code to extend the running
kernel, or so-called base kernel,of an operating
system.

3. Continue…
LKMs are typically used to add support for new
hardware and/or filesystems, or for adding system
calls.
Study of linux kernel and kernel modules
divided into 4 parts:
1. Development of a reasonably size dynamically
loadable kernel module for Linux kernel.
2. Passing command line arguments to a module.
3. Building modules for a precompiled kernel.
4. Implementing module for linux kernel

4. History
Linux is a modern, free operating system based
on UNIX standards.
First developed as a small but self-contained
kernel in 1991 by Linus Torvalds.
run efficiently and reliably on common PC
hardware, but also runs on a variety of other
platforms.
 Linux system has many, varying Linux distributions
including the kernel,applications, and
management tools.

5. The Linux Kernel:
Version 0.01 (May 1991)
o No networking.
o ran only on 80386-compatible Intel Processors and
on PC hardware.
o extremely limited device-drive support.
o supported only the Minix file system.
Linux 1.0 (March 1994)
o Support for UNIX’s standard TCP/IP networking protocols
o Device-driver support for running IP over an Ethernet
o Enhanced file system
o Support for a range of SCSI controllers for
high-performance disk access

6. Linux 2.0
Released in June 1996, 2.0 added two major new
capabilities:
o interfaceSupport for multiple architectures,
including a fully 64-bit native Alpha port
o Support for multiprocessor architectures
Other new features included:
o Improved memory-management code
o Improved TCP/IP performance
o support for internal kernel threads, for handling
dependencies between loadable modules, and for
automatic loading of modules on demand
o Standardized configuration

7. OTHER VERSION OF LINUX
 Available for Motorola 68000-series processors,
Sun Sparc systems, and for PCand PowerMac system..
 2.4 and 2.6 increased SMP support, added journaling
file system, preemptive kernel, 64-bit memory support .
 3.0 released in 2011, 20th anniversary of Linux,
improved virtualization support, New page write-back
facility, improved memory management.
Latest release4.0.2 (6 May 2015; 2 days ago)

8. PROCEDURE:
1.DEVELOPMENT OF REASONABLY SIZED
DYNAMIC LOADABLE KERNEL MODULE
FOR LINUX KERNEL
Modules are pieces of code that can be loaded and
unloaded into the kernel upon demand.
 They extend the functionality of the kernel
without the need to reboot the system.

9. Continue….
 For example, one type of module is the device
driver, which allows the kernel to access hardware
connected to the system.
 Without modules, we would have to build
monolithic kernels and add new functionality directly
into the kernel image.

10. Coding:
#include <linux/module.h> /* Needed by all modules */
#include <linux/kernel.h> /* Needed for KERN_INFO */
int init_module(void)
{
printk(KERN_INFO "Hello world 1.n");
/*
* A non 0 return means init_module failed; module
can't be loaded.
*/
return 0;
}
void cleanup_module(void)
{
printk(KERN_INFO "Goodbye world 1.n");

11. Kernel modules must have at least two
functions:
 a "start" (initialization) function called
init_module() which is called when the
module is insmoded into the kernel
 and an "end" (cleanup) function called
cleanup_module() which is called just before
it is rmmoded.

12. Linux command:
lsmod – List Modules that Loaded
Already.
insmod – Insert Module into Kernel.
modinfo – Display Module Info
rmmod – Remove Module from
Kernel

13. 2.PASSING COMMAND LINE
ARGUMENTS TO A MODULE:
 Modules can take command line arguments.
 To allow arguments to be passed to your module,
declare the variables that will take the values of the
command line arguments as global and then use the
module_param()to setup.
 The variable declarations and macros should be placed
at the beginning of the module.

14. Advantage of linux
Cost – The most obvious advantage of using Linux is the
fact that it is free to obtain, whileMicrosoft products are
available for a hefty and sometimes recurring fee .
Security – In line with the costs, the security aspect
of Linux is much stronger than that ofWindows.
Choice (Freedom) –The power of choice is a
great Linux advantage.

15. Disadvantages of Linux:
Understanding – Becoming familiar with
the Linux operating system requires
patience as well as a strong learning curve.
Compatibility – Because of its free
nature, Linux is sometimes behind the
curve when it comes to brand new
hardware compatibility
.

16. Conclusions
Linux is a flexible, robust node operating system for
Beowulf computational clusters.
Stability and adaptability set it apart from the legacy
operating systems that dominate desktop
environments.
It has spread quickly from its humble beginnings as a
student’s hobby project to a full-featured server operating
system with advanced features and legendary stability .