8/6/2019 Compiling a Kernel in Ubuntu

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Compiling a kernel in Ubuntu:

Basic steps:

1. Download required packages for building2. Download Source

3. Configure the build4. Fire the build5. Install the build6. Create initd image (optional)7. Configure Grub (optional)

Note: If possible su to root user before performing a kernel build. Alternatively use 'sudo' in all the commands listedbelow and 'fakeroot' for building.

1. Download required packages for Building

apt-get update

apt-get install kernel-package libncurses5-dev fakeroot wget bzip2initramfs-tools

2. Download source:

If you have no console, you can use the following commands:

cd /usr/srcwget http://www.kernel.org/pub/linux/kernel/v2.6/

or use a browser to download from www.kernel.organd place it in /usr/src

The current user directory should be /usr/src/ after the source is downloaded/

tar xjf source-file.bz2

create a symbolic link 'linux' which points to the kernel source, make this as the

working folder:

ln -s linux

cd /usr/src/linux

3. Configure the build

Copy the configuration of a working kernel.

cp /boot/config-`uname -r` ./.config

Launch the kernel config UI:

make menuconfig

After making required changes to the configuration, save and exit the tool

4. Fire the build

Do a clean if required to force a from scratch build [recommended]

make-kpkg clean

IMPORTANT:

To make use of all the cores, set the following environment variable:

export CONCURRENCY_LEVEL=X

where X= Number of Cores + 1 [gives arnd 90% utilization on all cores]

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8/6/2019 Compiling a Kernel in Ubuntu

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If you are root user fire build using:

make-kpkg --initrd --append-to-version=-custom kernel_image kernel_headers

otherwise use

fakeroot make-kpkg --initrd --append-to-version=-custom kernel_image kernel_headers

5. Install the build

Go to source directory:cd /usr/src

Install the image and header packages (.deb) that are created using the command

dpkg -i

Check in \boot to see whether the kernel image and initrd images for the new kernelare copied.

You may see the initrd image missing at times, follow step 6 and 7 to generate andinstall an initrd

6. Create initrd image (optional)

update-initramfs -ckv

eg: update-initramfs -ckv 2.6.24-11-generic

7. Configure Grub (optional)

Open the config file at \boot\grub\grub.cfg

In the entry for the new kernel add the following line to load the initrd image:

initrd /boot/

You are can restart:

shutdown -r now

Select the required kernel and boot up...

References:

http://www.howtoforge.com/kernel_compilation_ubuntuhttps://answers.launchpad.net/ubuntu/+source/initramfs-tools/+question/26781

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