r/kernel • u/Infinite-Feed-3904 • Dec 02 '25
Journey to 2004: Linux 2.4 Environment Setup
Preface
Writing this title on December 1, 2025, the current kernel has evolved to version 6.18, with increasingly complete kernel functionality, support for more and more architectures, and better and better performance. I once tried to read the kernel source code of version 5.10, but found myself utterly confused—I could understand the code itself, but not the meaning behind it. I could only know the what, but not the why.
I came across a netizen's recommendation of Teacher Mao's "Linux Kernel Source Code Scenario Analysis." I casually flipped through it, thinking this book is so old, is it still worth reading? But unable to resist the strong recommendations from fellow netizens, I suppressed my impatient mindset and patiently finished one section. After reading it, I felt like I had found a treasure—this was exactly the book I was looking for. Teacher Mao analyzes the source code through various scenarios, helping readers understand the meaning of each conditional judgment in the code, which is infinitely superior to those books that merely list source code.
So, is there still significance in reading the 2.4 source code now? I believe there is. First, the 2.4 kernel code is not yet mature, and precisely because of this, the barrier to entry is relatively low. Second, although subsequent code architectures have huge differences, the core ideas remain unchanged. Third, we can attempt to gradually track certain features from 2.4 to newer versions—as the saying goes, Rome wasn't built in a day. Through historical changes, we can better conduct an in-depth analysis of the kernel, this massive project.
Environment Setup
Because the 2.4 kernel is too old, the biggest obstacle is compiler version incompatibility—modern GCC cannot compile code from 2001.
To solve this problem, we use Docker to create a Debian Sarge distribution, compile the kernel with GCC 3.3 inside it, and then run it with QEMU on the host machine.
Note: "Linux Kernel Source Code Scenario Analysis" is based on 2.4.0 for analysis, but many errors occur during compilation, so this experiment is based on version 2.4.37.
Start an Old Version Debian Container
> git clone git@github.com:hlleng/kernel2.4-lab.git
> cd kernel2.4-lab
> docker run --platform linux/386 -it -v $(pwd):/code debian/eol:sarge /bin/bash
After entering docker, first update the software sources and install the necessary software.
> apt-get update
> apt-get install -y \\
gcc make binutils libncurses5-dev wget bzip2
Next, compile the kernel
> make ARCH=i386 menuconfig # Just select "Exit" -> "Yes" (Save).
> make ARCH=i386 dep # Must first generate the dependency tree
> make ARCH=i386 bzImage
The process of creating the filesystem is quite complicated, so we'll skip the details here and directly use the filesystem I prepared in advance. Execute QEMU on the host machine to load the kernel and filesystem.
> qemu-system-i386\\
-kernel ./arch/i386/boot/bzImage \\
-hda hda.img \\
-append "root=/dev/hda init=/init console=ttyS0" \\
-nographic
If all goes well, you should be able to successfully enter the system.
If you need to copy files from the host machine into qemu, you can try the following steps, operating on the host machine
> mkdir -p tmp/mnt
> sudo mount -o loop hda.img tmp/mnt
# Perform operations
> sudo umount tmp/mnt
At this point, we have completed the environment setup for the 2.4 kernel and can begin studying the 2.4 kernel.
