Automate Linux Kernel Builds

February 25, 2024

I wrote a small shell script™ to automate building new Linux kernels. I use this to build new kernels on my Debian systems:

#!/usr/bin/env bash

WORKSPACE='/home/gd/workspace'
LINUX="${WORKSPACE}/linux"

find "${WORKSPACE}" -type f \( -name 'linux-*deb' -o -name 'linux-upstream*' \) -mtime -3 -exec rm {} \;

cd "${LINUX}" || exit

git checkout .
git checkout master --force

git branch | while read -r branch; do
    [[ "$branch" =~ ^v ]] && git branch -D "${branch}"
done

git pull

version=$(git tag | sort -V | grep -v -E '*-rc*' 2>/dev/null | tail -1)
git checkout tags/"${version}" -b "${version}"

make mrproper
yes "" | make localmodconfig
make -j"$(nproc --all)" bindeb-pkg

1. First I setup two constant values, WORKSPACE and LINUX, to store paths to my workspace and my Linux source code directory, respectively.

2. Next I delete old files. I use the find command to search for files in my WORKSPACE that match the specific patterns of old builds (linux-*deb and linux-upstream*) and that are older than 3 days, then I delete them. This helps with keeping my filesystem cleared of old builds and package files.

3. Then I change the current directory to LINUX. If the directory does not exist or the command fails, my script exits to prevent further commands from executing in the wrong directory.

4. After than I reset and update the Linux kernel git repository:

   • git checkout . discards changes in the working directory.
   • git checkout master --force switches to the master branch, discarding any changes or differences forcefully.
   • I then delete all git branches starting with "v". These are from previous builds and are no longer needed.
   • git pull updates my local repository to the latest commit.

5. Next I select the latest stable version:

   I find the latest git tag that does not include a release candidate (-rc) version and set that as the current version. Then I check out this version into a new branch, naming it after the version tag.

6. Finally I compile the Linux kernel:

   • make mrproper cleans my local source tree, removing any previous configurations and compiled files.
   • make defconfig creates a default configuration file. I do this so I'm not asked about any new defaults when I run the next command.
   • make localmodconfig tailors my configuration for my exact system and also disables any modules that are not needed.
   • make -j"$(nproc --all)" bindeb-pkg compiles my kernel into Debian packages using all available processor cores, speeding up the compilation process.

linux (10) kernel (5) bash (3)