Compile The Linux Kernel

Compiling the Mainline Linux Kernel on Ubuntu: A Comprehensive Guide

Introduction:

Compiling the Linux Kernel in Ubuntu can be a rewarding but challenging task. This guide aims to simplify the process and help you configure the kernel to your specific hardware. Don't be discouraged if your first few attempts don't work; it's all part of the learning process. You can always revert to your last working Kernel using Grub Customizer.

Section 1: Setting Up Your Environment

• Using the Terminal:
• Locate your terminal application through the search or menu.
• If you prefer a lightweight GUI, Xubuntu is a great choice. It comes with a terminal in the Accessories menu.
• Create a directory for the kernel source code in your home directory:

mkdir source

Section 2: Downloading the Kernel Source

Visit kernel.org to choose the appropriate Linux Kernel version. If you're new to kernel compilation, consider using the latest stable release.

You can download the source directly to your compilation directory with:

wget https://cdn.kernel.org/pub/linux/kernel/v6.x/linux-6.5.5.tar.xz

Move the downloaded kernel source to your source directory:

mv linux-6.5.5.tar.xz source

cd source

tar -xvf linux-6.5.5.tar.xz

cd linux-6.5.5

Section 3: Install the necessary dependencies for compiling the kernel:

Before proceeding, all of the dependencies must be met first:

sudo apt-get install libqt5x11extras5-dev pkg-config libncurses-dev gawk flex bison openssl libssl-dev dkms libelf-dev libudev-dev libpci-dev libiberty-dev autoconf debhelper make lzop liblzo2-dev libzstd-dev vim curl

For Ubuntu 23.10+

sudo apt-get install qt6-base-dev qt6-tools-dev pkg-config libncurses-dev gawk flex bison openssl libssl-dev dkms libelf-dev libudev-dev libpci-dev libiberty-dev autoconf debhelper make lzop liblzo2-dev libzstd-dev vim curl

Also, any Linux version specific dependencies

sudo apt-get build-dep linux linux-image-$(uname -r)

We're going to use a tool called xconfig but that requires libqt5x11extras5-dev while menuconfig requires libncurses-dev. There's yet another tool called gconfig. This guide uses xconfig as it appears to be the most complete and easiest to use.

Section 4: Configuring Your Kernel

Create a new .config file based on your current kernel configuration:

sudo make oldconfig

If you want to add modules for your currently loaded hardware, use:

sudo make localmodconfig

To fine-tune your configuration interactively, use:

sudo make xconfig

The xconfig menu is huge but you can search for features to easily find and remove or add them. I search for keywords trace, profile, debug, symbols, virt, xen, and kvm. I remove these features from my build. You can also search for hardware that your PC uses like amd, intel, etc. Perhaps a network adapter such as realtek. This will take time to learn but using the make localmodconfig should make this process much faster and eaier.

Section 5: Compiling the Kernel

Compile the kernel with the following command, adjusting the flags as needed:

sudo make -j`nproc` LOCALVERSION=your_version CFLAGS="-O3 -march=native" CXXFLAGS="-O3 -march=native" CPPFLAGS="-O3 -march=native" bindeb-pkg

Replace `your_version` with a name that identifies your customized kernel.

Section 5: Installing the New Kernel

Navigate to the directory containing the generated .deb files:

cd ..

Install the new kernel and headers in the following order:

sudo dpkg -i linux-headers*.deb

sudo dpkg -i linux-image*.deb

Section 6: Managing Boot Options with Grub Customizer

Install Grub Customizer to manage your boot options:

sudo add-apt-repository ppa:danielrichter2007/grub-customizer

sudo apt-get update

sudo apt-get install grub-customizer

Use Grub Customizer to set your new kernel as the default boot option and ensure the boot menu is displayed.

Don't forget to save your configuration. It's important to enable the boot menu as well. If the newly install Kernel fails then the system can be rebooted and you can choose the last working Kernel from the menu.

Conclusion

Restart your system and cross your fingers! If any issues arise, you can start over by cleaning the compilation files and modifying the .config file as needed.

If your Kernel fails to boot, or is missing a feature or hardware support that you forgot, simply open a Bash terminal in the directory where your source code is and type:

sudo make clean

Then go to section 4 and modify the .config using xconfig tool.

By following this guide, you'll be able to compile and customize your Linux Kernel to better suit your hardware and preferences. Remember, it's a learning process, and each attempt will bring you closer to a perfectly tailored kernel. Good luck!