Jan 28, 2026 - 1 min read

Kernel exploration and experimentation

I am starting to dig again into some linux kernel internals, so I decided to write down (mostly for myself) all the results and documents I found to be useful.

QEmu

I wanted to emulate the linux kernel using QEMU.

I was inspired by this post even if it's outdated. This post is also a good reference.

Filesystem

I used this script from the syzkaller project.

qemu-system-x86_64 \
  -kernel $KERNEL_PATH/arch/x86/boot/bzImage \
  -append "console=ttyS0 root=/dev/sda debug earlyprintk=serial slub_debug=QUZ"\
  -hda $IMAGE_PATH/trixie.img \
  -net user,hostfwd=tcp::10021-:22 -net nic \
  -enable-kvm \
  -nographic \
  -m 2G \
  -smp 2 \
  -pidfile vm.pid \
  2>&1 | tee vm.log

Kernel build

I want to keep an eye on staging drivers to find some easy code style fix to have the chance to send a first patch. Here are the steps I am following

Download linux-next

Following the documentation you can find here you can start tracking the linux-next development branch.

We start cloning the mainline kernel

$ git clone https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git

Then we add a remote tracking branch for linux-next

$ cd linux
$ git remote add linux-next https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git

Every day you want to sync with the latest developments:

$ git remote update

Then delete local branches tracking daily tags

$ git branch -D my_local

List daily tags to find the latest one:

$ git tag -l "next-*" | tail

Now choose the latest one and track it using a local branch

$ git checkout -b my_local next-20260209

Config

I started by using the make localmodconfig to have a booting build of the kernel based on my running config.

Follow kernel developments

The current developer flow rotates around two tools:

  • b4 which you can install with your distro package manager or from PyPi.
  • lei also packaged by major distros

b4

lei

This tool is very useful to get a local copy of the kernel mailing lists you are interested in without subscribing and, most importantly, to get a local copy of the conversations in a given time interval (e.g. the last month) to browse them with mutt or another mail client while offline and/or without using the archives web interface.

2026-01-28