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How To Recompile the Kernel in Ubuntu

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In this article, we will walk you through the process of recompiling the kernel in Ubuntu. Recompiling the kernel can be necessary for various reasons, including adding custom patches, enabling or disabling specific kernel features, or optimizing the kernel for specific hardware.

Quick Answer

To recompile the kernel in Ubuntu, you need to install necessary packages, download the kernel source code, customize the kernel configuration, build the kernel, install the newly compiled kernel, and update the bootloader configuration. This process allows you to add custom patches, enable/disable kernel features, or optimize the kernel for specific hardware.

Prerequisites

Before we start, ensure that you have administrative access to your Ubuntu system and a stable internet connection. This guide is written for Ubuntu 12.04 x86 64-bit. For different versions or architectures, some commands or package names may vary.

Step 1: Installing Necessary Packages

Firstly, we need to install some necessary packages. Open your terminal and type the following command:

sudo apt-get install build-essential kernel-package fakeroot libncurses5-dev
  • build-essential: Contains references to all the packages needed to compile a Ubuntu binary package.
  • kernel-package: Provides the make-kpkg utility which is used to build kernel related Debian packages.
  • fakeroot: Allows a non-privileged user to run programs as root in a safe manner.
  • libncurses5-dev: Library for terminal handling.

Step 2: Download the Kernel Source Code

Next, we need to download the source code of the kernel that we want to recompile. Use the following command to do this:

apt-get source linux-image-$(uname -r)

This command will download the source code for your currently running kernel.

Step 3: Enter the Source Code Directory

Once the source code is downloaded, navigate to the source code directory by typing:

cd linux-*

Step 4: Customize the Kernel Configuration

Now, we need to customize the kernel configuration. If you want to use the current kernel’s configuration, run:

make oldconfig

If you have a third-party .config file, copy it to this directory and run:

make menuconfig

or

make xconfig

These commands will open a graphical interface to configure the kernel.

Step 5: Build the Kernel

After customizing the kernel configuration, we can now build the kernel. Run the following command:

fakeroot make-kpkg -j `nproc` --initrd --append-to-version=my-very-own-kernel kernel-image kernel-headers
  • -j: This option sets the number of jobs (commands) to run simultaneously. Here we use nproc to get the number of available CPUs.
  • --initrd: Creates an initial ramdisk for the kernel.
  • --append-to-version: This option allows you to append a custom string to the kernel version. Replace my-very-own-kernel with a custom string to identify this build.

Step 6: Install the Newly Compiled Kernel

Once the kernel is built, we can install it using the following command:

sudo dpkg -i ../linux-image-*.deb ../linux-headers-*.deb

This command will install the kernel image and header files.

Step 7: Update the Bootloader

Finally, we need to update the bootloader configuration to include the new kernel. Run the following command to do this:

sudo update-grub

After completing these steps, you can reboot your system and select the newly compiled kernel from the bootloader menu.

Conclusion

Recompiling the kernel in Ubuntu may seem like a daunting task, but with a bit of patience and understanding, it can be a rewarding learning experience. Always remember to back up your data and configurations before making any significant changes to your system. Happy coding!

What is the purpose of recompiling the kernel in Ubuntu?

Recompiling the kernel in Ubuntu can be necessary for various reasons, including adding custom patches, enabling or disabling specific kernel features, or optimizing the kernel for specific hardware.

What are the prerequisites for recompiling the kernel in Ubuntu?

Before recompiling the kernel, ensure that you have administrative access to your Ubuntu system and a stable internet connection.

Which packages do I need to install before recompiling the kernel?

You need to install the following packages before recompiling the kernel: build-essential, kernel-package, fakeroot, and libncurses5-dev.

How do I download the kernel source code?

To download the source code of the kernel, use the command apt-get source linux-image-$(uname -r).

How do I customize the kernel configuration?

To customize the kernel configuration, you can use the command make oldconfig to use the current kernel’s configuration or make menuconfig or make xconfig to open a graphical interface for configuration.

How do I build the kernel after customizing the configuration?

After customizing the kernel configuration, you can build the kernel using the command fakeroot make-kpkg -j nproc --initrd --append-to-version=my-very-own-kernel kernel-image kernel-headers.

How do I install the newly compiled kernel?

To install the newly compiled kernel, use the command sudo dpkg -i ../linux-image-*.deb ../linux-headers-*.deb.

How do I update the bootloader to include the new kernel?

To update the bootloader configuration, run the command sudo update-grub.

Can I revert back to the previous kernel after recompiling?

Yes, you can revert back to the previous kernel by selecting it from the bootloader menu during system startup.

Is it recommended to back up data before recompiling the kernel?

Yes, it is always recommended to back up your data and configurations before making any significant changes to your system.

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