Compiling custom kernel has its own advantages and disadvantages.
However, new Linux user / admin find it difficult to compile Linux
kernel. Compiling kernel needs to understand few things and then just
type couple of commands. This step by step howto covers compiling Linux
kernel version 2.6.xx under Debian GNU Linux. However, instructions
remains the same for any other distribution except for apt-get command.

Step # 1 Get Latest Linux kernel code

Visit http://kernel.org/ and
download the latest source code. File name would be
linux-x.y.z.tar.bz2, where x.y.z is actual version number. For example
file inux-2.6.25.tar.bz2 represents 2.6.25 kernel version. Use wget
command to download kernel source code:

`$ cd /tmp

$ wget http://www.kernel.org/pub/linux/kernel/v2.6/linux-x.y.z.tar.bz2`

Note: Replace x.y.z with actual version number.

Step # 2 Extract tar (.tar.bz3) file

Type the following command:

`# tar -xjvf linux-2.6.25.tar.bz2 -C /usr/src

cd /usr/src`

Step # 3 Configure kernel

Before you configure kernel make sure you have development tools
(gcc compilers and related tools) are installed on your system. If gcc
compiler and tools are not installed then use apt-get command under
Debian Linux to install development tools.

# apt-get install gcc

Now you can start kernel configuration by typing any one of the command:

  • $ make menuconfig - Text based color menus, radiolists &
    dialogs. This option also useful on remote server if you wanna compile
    kernel remotely.

  • $ make xconfig - X windows (Qt) based configuration tool, works best under KDE desktop

  • $ make gconfig - X windows (Gtk) based configuration tool, works best under Gnome Dekstop.

For example make menuconfig command launches following screen:

$ make menuconfig

You have to select different options as per your need. Each
configuration option has HELP button associated with it so select help
button to get help.

Step # 4 Compile kernel

Start compiling to create a compressed kernel image, enter:

$ make

Start compiling to kernel modules:

$ make modules

Install kernel modules (become a root user, use su command):

`$ su -

make modules_install

`

Step # 5 Install kernel

So far we have compiled kernel and installed kernel modules. It is time to install kernel itself.

# make install

It will install three files into /boot directory as well as modification to your kernel grub configuration file:

  • System.map-2.6.25

  • config-2.6.25

  • vmlinuz-2.6.25

Step # 6: Create an initrd image

Type the following command at a shell prompt:

`# cd /boot

mkinitrd -o initrd.img-2.6.25 2.6.25`

initrd images contains device driver which needed to load rest of
the operating system later on. Not all computer requires initrd, but it
is safe to create one.

Step # 7 Modify Grub configuration file - /boot/grub/menu.lst

Open file using vi:

# vi /boot/grub/menu.lst

title Debian GNU/Linux, kernel 2.6.25 Default
root (hd0,0)
kernel /boot/vmlinuz root=/dev/hdb1 ro
initrd /boot/initrd.img-2.6.25
savedefault
boot

Remember to setup correct root=/dev/hdXX device. Save and close the
file. If you think editing and writing all lines by hand is too much
for you, try out update-grub command to update the lines for each
kernel in /boot/grub/menu.lst file. Just type the command:

# update-grub

Neat. Huh?

Step # 8 : Reboot computer and boot into your new kernel

Just issue reboot command:

# reboot

For more information see:

  • Our Exploring Linux kernel article and Compiling Linux Kernel module only.

  • Official README file has more information on kernel and software
    requirement to compile it. This file is kernel source directory tree.

  • Documentation/ directory has interesting kernel documentation for you in kernel source tree.

Original source:http://www.cyberciti.biz/tips/compiling-linux-kernel-26.html