In the previous post I figured out all the internal weirdness of Linux booting to get BodgeOS running on actual hardware. The next goal was very clear: getting to a graphical environment. At the start of this month I had the goal set to running a web browser before 2024 ends but I've now slightly adjusted my goals down to being able to type this blog post in a terminal on my new OS.
So what does it take to get graphics in Linux? well the first component is very clear from experience: Mesa. This is the component that provides all the userspace components for the graphics drivers. I started with checking out both the LFS mesa build instructions and the Alpine and ArchLinux mesa packages. This is not a very nice package to build due to the large dependencies it has. This one project contains all the graphical hardware related code for any GPU Linux will run on and due to that it depends on several programming languages and compilers.
I have tried stripping down this package as much as possible: no X11 support, only intel graphics, only EGL for 3D acceleration, no extra components, no software rasterisation. This makes Mesa relatively easy to build. With only the i915 gallium driver for intel graphics I don't have to bring up any of the Vulkan, rust or llvm dependencies to get basic graphics.
The desktop
So I had to pick a graphical environment as goal to run. There are many choices for this and even more opinions on what the best one. I picked Sway here since it's a Wayland based environment so I don't have to go figure out all the X11 stuff. It's also very simple to build compared to something like Gnome or KDE Plasma. I guess there will be someone that has figured out that some random ancient window manager can be built with even less dependencies but this is the smallest one from the desktops I've actually used before :)
The dependency chain for Sway is pretty simple: wlroots abstracts away all the Wayland stuffs and makes it actually communicate with Mesa. Then it has some extra dependencies to render text and simple graphics to draw the bars and window decorations.
So I started figuring out the minimum dependencies for every component in the dependencies of wlroots and Sway and package all the things are that are needed. This included fixing up the Python udev bindings from my systemd package, packaging the Wayland protocols, a bunch of Xorg keyboard stuff because it seems like keymaps are still used from x* packages and finally seatd to provide a way to get a session for the desktop.
Sway
For Sway the dependencies got a lot more annoying to compile since it depends on Pango and Cairo for rendering and those build systems were just a massive pain to deal with. It seems like the higher you get in the stack of a Linux system the more bullshit is added to build systems to make things "easier". My particiular painpoint in the Sway dependencies is glib and gobject-introspection which is not sufficiently documented and seems to work on magic.
Font rendering
Along with Pango I also had to bring up the whole font system in Linux. This involves Pango, Cairo, HarfBuzz, Glib and several obscure libraries for font processing. These packages are fun because they contain circular dependencies so I had to build them a few extra times.
First attempt at booting
After getting the 41 packages built that are required to get to a very minimal Sway experience I generated a new rootfs and tried booting it on a laptop.
This started the hunt for optional dependencies that were not optional for my usecase. The first one was that seatd could not actually make a session for me because I had zero backends compiled in. This was a relatively simple fix of just enabling the builtin backend in seatd to get at least some session.
Next came the graphical stack issues...
It first took a bit of time figuring out which of these errors was the fatal one I should be looking at, it was not one of the red ones in this case. The important error here was the "iris: driver missing" line which is from Mesa. I had initially assumed that i915 was the hardware backend I needed for my laptops since it's the name I've always come across. Apparently my laptops are old but not old enough to require i915 graphics, instead I needed to enable the iris backend.
Enabling the flag for iris in Mesa is very simple, but the hard part is the additional dependencies this adds to Mesa. Iris requires libclc which is the library for OpenCL. This depends on SPIR-V and LLVM which means packaging another massive project.
LLVM was by far the biggest time sink for a single package I've had so far. This package takes absolutely forever to compile and I was building this on an x280 with 8GB ram. Since this laptop has 8 cores I have built everything with -j8 so far which works fine except for LLVM where I had to drop to -j4 to not run out of memory while building. I had the same issues with Clang as well and together I've spend 3 days waiting on either one of them to build to hit the next issue that needed slight adjustments in the flags.
With LLVM working I managed to build all the packages required for SPIR-V and libclc so I could finally build the iris backend in Mesa. Since I now had a few extra dependencies packaged I also could enable llvmpipe as software rasterizer and osmesa, the off-screen mesa renderer.
Sway starts
With my graphics drivers fixed I finally got Sway to run. This was a very unexciting start though since the only thing it actually rendered was a black screen with my cursor. To make this more annoying to debug it also did not allow me to switch back to a TTY with ctrl+alt+F{1,2,3,4} anymore to see any of the debug logs. This forced me to build the thing I had been postponing: openSSH.
By launching Sway through an SSH session I noticed that the first thing I was missing was the swaybg binary which apparently is a seperate package, that explains why by background was completely black. This was packaged and built in a few minutes which fixed 90% of the screen area. The next mystery was the missing bars.
Suprisingly with all the logging turned to max in Sway I still got no error message whatsoever about the bars not showing up. Even more suprising is that if I reloaded the config a few times there occiasionally were some graphical artifacts where the bars were supposed to be.
After trying a few things and guessing even more things I figured out why it did not show up: I have the entire font rendering pipeline working but I haven't packaged a single font.... So that was an easy fix.
To complete the minimal working environment I also built the foot package to have a terminal available that did not have too many extra dependencies to work.
There's also several more low-level things I had to figure out on the way, like my installed system not having any locales available. This was quickly fixed by importing the locale-gen script from ArchLinux to generate the locales I need and fixing up my glibc package to put the locale files in the right location.
Branding
So now I have the bare minimum I could focus on more cleanup work and small features. One of those is making the default wallpaper for my distro. I ended up doing the same thing I always do when I get annoyed with Inkscape not doing what I want: Rendering the graphics directly using Python instead.
I made a small python script that uses Pillow to render a wallpaper at the requested resolution.
This was inspired by the KiCad PCB editor I had open. I thought it was topical since the distro name was also inspired by my electronics projects :D
Continuing on
So this most likely completes my BodgeOS project for this year. I'm now up to 238 APKBUILD scripts in the repository which build ~900 packages for the distribution.
I'll have to package a lot more probably for my next goal, which is getting Firefox to run. This includes some things I've been avoiding like figuring out how to bring up the rust ecosystem and packaging GTK. While the current packages might've been hard to figure out, the rust ecosystem seem to actively resist packaging efforts to make it even harder. Maybe I should get more of Python packaged first so I can use my own utilities for working with APKBUILD files.
Since this is also the last blog post of the year, happy new year everyone!