Having Fun with CLFS and musl

#funtoo (4)#bootstrap (1)

Experimenting with building a CLFS prefix with musl instead of glibc.

I've been playing around with CLFS over the last week or two, and it has been super fun. Well, that's at least when things worked :D

More specifically, I've been experimenting with replacing glibc with musl and seeing how complicated it would be to get running. And, spoiler alert, considering you're currently reading this, it's safe to assume I've had a fair bit of success with it.

You might be wondering how Funtoo comes into the story, and I got the answers. We recently announced a new Funtoo project called Evolved Bootstrap. The idea behind it is to develop a way to bootstrap a Funtoo Linux system completely from scratch, using any Linux-like environment, for any architecture. The end goal is to have a straightforward and automated way to port Funtoo for any currently unsupported architecture.

One cannot fly into flying, though, so we need to learn how to walk first: we need a way of bootstrapping a minimal cross-compiled environment that we can expand upon later. And this is basically what the concept of CLFS is: building a Linux system from scratch for another architecture. Right now, we're running through the CLFS books and seeing what it takes to get things running for different architectures, with various package upgrades, etc.

The coolest part about the Evolved Bootstrap, in my opinion, is that it will also unlock the doors to alternative init systems, libc implementations, compilers, etc. That's why I decided to experiment with replacing glibc with musl. The CLFS embedded book already used musl, but as the name may suggest, it caters to building Linux systems for embedded devices and doesn't cover our use case.

The musl project has always been super interesting to me, but I've never had a real chance to play around with it on Funtoo, and it has never been a top priority for us to support. The Evolved Bootstrap project gave me a valid excuse to dive right into it, though.

By mixing and matching the standard and embedded CLFS books and through countless workarounds, I've managed to get a chrootable environment going with musl instead of glibc. You can find my instructions on the Funtoo wiki here. They are a more concise and copy-and-paste-ready version of the CLFS book, and I've tested them for x86_64 and aarch64 so far. I'm currently working on getting them to work for powerpc64 as well.

If the Evolved Bootstrap project sounds like fun to you, you can learn more about it here, and you can stop by our Discord if you feel like chatting to us about it and perhaps even getting involved.