- cross-posted to:
- [email protected]
- cross-posted to:
- [email protected]
I’ve been working on a “Linux Inside Out” series and wrote a post that might interest folks here who like low(ish)-level / OS internals.
The idea is to dissect the components of a Linux OS, layer by layer, and build a mental model of how everything fits together through experiments.
The first part is about the kernel, in the post I:
- take the same kernel image my distro boots from /boot
- boot it directly with QEMU (no distro, no init system)
- watch it panic
- write a tiny Go program and use it as PID 1
- build a minimal initramfs around it so the kernel can actually start our process
The goal isn’t to build a real distro, just to give a concrete mental model of:
- that the Linux kernel is just a compressed file, you can boot it
- without anything else
- what the kernel actually does at boot
- how it hands control to userspace
- what PID 1 / init is in practice
- what is kernel space vs user space
Link: https://serversfor.dev/linux-inside-out/the-linux-kernel-is-just-a-program/
I’m the author, would be happy to hear from other devs whether this way of explaining things makes sense, and what you’d add or change for future posts in the series.
Hope you find it useful.
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Thank you, this is a great explanation. I look forward to the rest of this series.
Edit: I successfully booted a Debian kernel using this tutorial, though I wrote the init program in C++ instead of Go. The process is pretty much the same, but you have to add the
-staticflag to g++ since the C runtime is not included in the initramfs. This might be obvious to more seasoned programmers but it took me a minute to figure it out.Thank you for the feedback.
That looks simple when someone (you) say it simply.
Thank you for that. 😌
This is very cool, thanks for sharing!
I did a similar exercise a decade ago with HTTP and it was fun and eye-opening.
It’s a very good explanation. I like that it is short and hands on. For me, it is pitched at the right level and the practical style keeps it very grounded.
what you’d add or change for future posts in the series
I wouldn’t change anything to do with the content! Speaking personally, I’m a fan of full text RSS feeds, so I’d love one on this blog if that’s an option :)
I think there is one. All the way at the bottom of the page I see a link for RSS and I was able to add it to my RSS reader. It looks like everything is there unless I am missing something.
I’m not sure if your RSS reader is getting the content through some special way. The feed itself only has the first two paragraphs:
<item> <title>The Linux kernel is just a program</title> <link>https://serversfor.dev/linux-inside-out/the-linux-kernel-is-just-a-program/</link> <guid isPermaLink="true">https://serversfor.dev/linux-inside-out/the-linux-kernel-is-just-a-program/</guid> <description>Most books and courses introduce Linux through shell commands, leaving the kernel as a mysterious black box doing magic behind the scenes. In this post, we will run some experiments to demystify it: the Linux kernel is just a binary that you can build and run.</description> <pubDate>Mon, 01 Dec 2025 00:00:00 GMT</pubDate> </item>
Thank you for the feedback.
Sure, I will look into the RSS plugin config. :)
Nice article. Waiting for the upcoming parts.
Blinry did something similar not to lomg ago, maybe it’s interesting for you, too: https://blinry.org/tiny-linux/
This looks really interesting. I’ll have a look when I get home.
This sounds awesome. I’m going to read this tomorrow when I can give it my full attention.
That’s so cool! Thanks for sharing it!
