Package a Custom Kernel with ukpack

This guide explains how to create a custom Linux kernel package using the tool ukpack. To create a kernel package a Git repository containing a custom kernel tree is needed. The repository should be based on an upstream Linux kernel version <kernel_version>.

Please, execute the Your first Kernel package tutorial. This provides a sample project.

Clone Required Repositories

First, clone the ukpack repository:

git clone https://kernel.ubuntu.com/forgejo/esmil/ukpack.git

Then, download the upstream Linux kernel source from which the custom kernel is based:

wget https://cdn.kernel.org/pub/linux/kernel/v6.x/linux-<kernel_version>.tar.xz

Next, clone the custom kernel repository:

git clone https://github.com/your_username/your_custom_kernel.git
cd your_custom_kernel/

Sync with Upstream Kernel

If the custom kernel tree is based on the Linux stable branch, you can add the upstream repository as a remote and fetch a specific tag:

git remote add linux-stable https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
git fetch --depth 1 linux-stable tag v<kernel_version>

Create Kernel Package Configuration

Inside the directory of your custom kernel repository (your_custom_kernel), create a your_kernel.toml file with the following content:

your_kernel (<kernel_version>-<local_version>) noble; urgency=medium
 * Initial packaging
 -- Your Name <[email protected]> Wed, DD MMM YYYY HH:MM:SS +TZ
---
arch = "<your_architecture>"
config = "arch/<your_architecture>/configs/your_defconfig"
orig = "v<kernel_version>"
[pkg.source]
Maintainer = "[email protected]"

This file contains both configuration options (below the ---) and changelog entries keeping track of changes to your custom kernel. At first this file has to be created manually, but on re-packaging updates to this file can be done with the command dch -c your_kernel.toml, which automatically appends a changelog entry on top of the last one.

Build the Kernel Package

Create an output directory outside your kernel tree and run ukpack:

mkdir ../ukpack.output/
../ukpack/ukpack -o ../linux-<kernel_version>.tar.xz -t . -d ../ukpack.output/ your_kernel.toml

Sign the Package

Change into the output directory and sign the package:

cd ../ukpack.output
debsign *.changes

Next Steps

After signing, you can proceed with testing or uploading the package.