Linux Kernel

The Saigon CTT
Linux Kernel
The Saigon CTT
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Objectives
Objectives

Define kernel properties

Demonstrate new kernel preparation

Identify and use kernel configuration tools

Recompile and install a kernel

Identify kernel modules

Configure LILO to use a new kernel
The Saigon CTT



The Linux Kernel
The Linux Kernel

It’s loaded at initial bootup of Linux system,
manages activities : I/O, memory, processes,
network interface,…


Why would you want to build a new kernel ?
(newer hardware, faster, more stable, …)

Kernel can be built with 2 basic options :
•
Device drivers can be built directly into the kernel
binary itself
•
Device drivers can be built as external modules to the
kernel
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Kernel Version Numbering
Kernel Version Numbering

Kernel version numbers are made by three
basic components:
- The major number
- The minor number
- The micro number (patch number)
There is the fourth number, sometimes
applied after a dash is genarally the patch
level , applied by kernel maintainers
Ex : 2 . 4 . 7 - 10
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

Kernel Version Numbering
Kernel Version Numbering

Kernel version numbering is very structured :
-
The minor number is even = stable version
-
The minor number is odd = development ver.
-
A patch constitutes a more precise
measurement of the kernel version. All patchs to
the kernel are cumulative. You simply have to
obtain and apply the latest patch for the kernel to
be sure you have the most up-to-date patched
support

To find out what kernel you are running :
# uname -r
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Recent Kernel Changes
Recent Kernel Changes

There are many changes from 2.2 to 2.4
-
Itanium and X86-64 AMD Hamer CPU support
-
Improve PnP/hot swappable device regconition

-
Journaling file systems : ext3, ReiserFS, ..
-
…
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


Preparing For The New Kernel
Preparing For The New Kernel

See
/usr/src/linux/Documentation/Changes

Software tools

The source tree (source code)

Apply patches to the kernel source code
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


Software Tools
Software Tools

make : determines which pieces of a large
program need to be recompiled
and compile them. It executes
commands in Makefile (sometime

named makefile) to update
programs or module components

C/gcc : C compiler integrated into gcc

binutils: a collection of binary utilities :
gas(assembler),ld(likner),
nm, ranlib, objdump, …
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


The Source Tree
The Source Tree

Kernel source released as a zipped tar file ,
extension of .tar.gz or .tar.bz2
Ex: linux-2.4.19-16.tar.gz

You should NEVER unpack your kernel
sources directly into /usr/src/linux
# mkdir /usr/src/linux-2.4.19-16
# tar xzfv linux-2.4.19-16.tar.gz –C
/usr/src/linux-2.4.19-16