How to Build a Linux Kernel from Scratch: A Step-by-Step Guide

The Linux kernel constitutes the core foundation of every Linux distribution. The Linux kernel is in charge of communicating with hardware and software as well as allocating the available resources. The kernel forms the fundamental building block upon which the entire operating system relies. It also ensures the seamless interaction between the hardware and the software.Let us discuss how to build a Linux kernel from scratch. Through this step-by-step guide, our goal is to explain how to customize and build our own Linux kernel very easily.

Why Do We Need to Build a Linux Kernel from Scratch?

The compilation of the Linux kernel from scratch code is a fundamental skill. When we start on this installation, we are preparing to dive into the deep elements of the Linux kernel. Therefore, we improve our overall understanding of its inner workings. We get the ability to modify our Linux kernel according to our needs and requirements. This ability becomes very useful when developing new system functions as it enables the experimental features that aren’t enabled by default and provides many more options.

Basic Requirements to Build a Linux Kernel

We just need the following requirements to build the Linux kernel:

Linux Operating System: Installed Linux OS in your computer.
Command Line Access: We must know the use of the terminal/command line to execute the required steps during the kernel building process.
Sudo or Root Privileges: We must make sure that our user account has “sudo” or “root” privileges to perform the system-level tasks.
Enough Disk Space: We must need at least 10 GB of available disk space to install the Linux kernel.
Required Packages: We must install these important packages such as Git, Fakeroot, Build-Essential, Ncurses-Dev, XZ-Utils, LibSSL-Dev, BC, Flex, LibElf-Dev, and Bison.

Steps to Build a Linux Kernel from Scratch

Here are the steps to follow:

1. Download the Latest Kernel Version

At first, we need to download the latest kernel version from the official site.

$ wget https://cdn.kernel.org/pub/linux/kernel/v6.x/linux-6.5.9.tar.xz

2. Extract the Kernel Code

We can extract it using the “tar” command after the source code is downloaded in our Linux.

$ tar xvf linux-6.5.9.tar.xz

3. Install All the Required Packages

We can use the following command in our Linux terminal to install the required packages:

$ sudo apt-get install git fakeroot build-essential ncurses-dev xz-utils libssl-dev bc flex libelf-dev bison

4. Configure the Kernel in Our Terminal

This downloaded kernel has all the default configuration. We can start by navigating to the kernel directory using the “cd” command in our terminal.

$ cd linux-6.5.9

After that, we need to copy the existing Linux config file to the kernel directory.

~/linux-6.5.9 $ cp -v /boot/config-$(uname -r) .config

We can make changes to the configuration. To make the changes, we can use the “make menuconfig” command which opens an interactive configuration menu. Here, we can select various options including firmware, file systems, and network settings.

5. Build the Kernel Using the “Make” Command

Now, we can use the following command to start the kernel building process:

$ make

This step compiles the kernel. This compilation may take several minutes.

6. Install the Modules and Kernel

After the successful compilation, we can finally install the modules and kernel. This step ensures that the necessary modules are in place for the new kernel.

$ sudo make modules_install

Finally, we can install the kernel and related configuration files to the “/boot” directory and generate a “system.map”.

$ sudo make install

Conclusion

We can make a Linux kernel from scratch with the help of our Linux OS. We get the idea to reconfigure and explore more opportunities by understanding how to build a Linux kernel from scratch. By understanding this article, we can improve our overall skill in modifying the kernel.