Kernel Dojo

A hands-on environment for learning Linux kernel development. Build, run, and hack on the kernel inside QEMU — no risk to your host system.

What's included

• Automated kernel build — fetches kernel source and builds a QEMU-bootable image with one command
• QEMU runner — boots the kernel with networking, SSH, and module loading pre-configured
• Example modules — annotated kernel modules to learn from and extend
• Scaffolding — quickly create new modules based on a working template

Prerequisites

Install dependencies for your distro:

make install

Supports apt, dnf, pacman, and zypper. You'll also need clang, lld, and llvm installed separately.

Getting started

1. Get the kernel source

make clone                  # clones linux-stable at the pinned version

The default is Linux 6.18.6. Override with:

make clone KERNEL_VERSION=6.12.0

2. Build the kernel

./tools/build.sh -d linux-6.18.6

This produces a bootable image at linux-6.18.6/arch/x86/boot/bzImage.

3. Boot in QEMU

make run

Connect via SSH on port 52222. Override CPU count and memory:

NRCPU=4 MEMORY=8192 make run

Writing kernel modules

Build a module

make mod -E M_DIR=modules/process-times/

Example modules

Module	Description
bare-module	Minimal loadable module — a clean starting point
process-times	Captures per-process CPU times via a kernel module

Project layout

kernel-dojo/
├── modules/           # Kernel modules
│   ├── bare-module/    # Template module
│   └── process-times/  # Example: process CPU time tracking
├── tools/
│   ├── build.sh        # Kernel build script (clang/LLVM)
│   ├── start_qemu.sh   # QEMU launcher with networking
│   ├── genmake.sh      # Makefile generator for modules
│   └── host_lib.sh     # Shared shell utilities
├── readings/           # Notes and references
├── linux-6.18.6/       # Kernel source (after make clone)
└── Makefile

Useful make targets

Target	Description
make install	Install build dependencies
make clone	Clone the kernel source
make run	Boot the kernel in QEMU
make scope	Build and open a cscope index of the kernel
make clean	Clean the kernel build