@prologic@twtxt.net Oh! 🤔

@prologic@twtxt.net That might be a challenge, at least in 16-bit Real Mode: The OS follows the model of COM files on DOS, i.e. the size of the binary cannot exceed 64 KiB and heap+stack of the running program will have to fit into that same 64 KiB. 😅 (The memory layout is very rigid, each process gets such a 64 KiB slice.)

And in 64-bit Long Mode, there is no “kernel” yet. The thing in the video is literally just a small bare-metal program.

But some day, maybe. 😃

Seeing this run on real hardware is so satisfying, even if it’s just a small example. 😅

https://movq.de/v/ec46b8cf99/netbook.mp4

My little toy operating system from last year runs in 16-bit Real Mode (like DOS). Since I’ve recently figured out how to switch to 64-bit Long Mode right after BIOS boot, I now have a little program that performs this switch on my toy OS. It will load and run any x86-64 program, assuming it’s freestanding, a flat binary, and small enough (< 128 KiB code, only uses the first 2 MiB of memory).

Here I’m running a little C program (compiled using normal GCC, no Watcom trickery):

https://movq.de/v/b27ced6dcb/los86%2D64.mp4

https://movq.de/v/b27ced6dcb/c.png

Next steps could include:

• Use Rust instead of C for that 64-bit program?
  
• Provide interrupt service routines. (At the moment, it just keeps interrupts disabled.)

In case you haven’t seen it yet:

Matt Godbolt’s “Advent of Compiler Optimisations”!

https://www.youtube.com/playlist?list=PL2HVqYf7If8cY4wLk7JUQ2f0JXY_xMQm2

@prologic@twtxt.net And I froze my ass off yesterday at -5°C and strong winds. 🤣

@prologic@twtxt.net 🎄 Merry Christmas and stuff 😅🎅

@lyse@lyse.isobeef.org Lovely! We also just had some snow. 😃 Not a lot, but still. 😅

(Lol, I totally read that as “rootfs”. 🤪)

@lyse@lyse.isobeef.org Oooh, nice! ⛄ We only have cold stormy weather over here. 🥴

Oh, that’s cute: https://movq.de/v/046fb6ee70/s.png DuckDuckGo puts a little helmet on the duck when you search for Skyrim. (Katria is a Skyrim character.)

@lyse@lyse.isobeef.org Thanks. 😅 (Do I say that? The WM can’t answer. 🤣)

Mastodon has a “Wrapstodon 2025” now, showing you a “wrap up” of the year. Of course, a pointless funny shitpost was my most “successful” post in 2025. 😂

https://movq.de/v/b9cf9e3ca0/s.png

@prologic@twtxt.net I’ve been awake at that time, didn’t notice anything. 🤔 Where was that BGP analyzer again … 😅 There’s a tool that keeps track of these things, right? I forgot what it was.

@prologic@twtxt.net Hm, I didn’t notice anything. Perhaps I was asleep? 😅

@prologic@twtxt.net You write so much code … it’s incredible. 😅

This feels useful: Rust’s Block Pattern

@lyse@lyse.isobeef.org These tables get shuffled around every time your OS switches to another process. It’s crazy that so much is going on behind the scenes.

@lyse@lyse.isobeef.org I was surprised by that as well. 😅 I thought these were features that you can use, but no, you must do all this.

By the way, I now fixed the issue that I mentioned at the end and it works on the netbook now. 🥳

https://www.uninformativ.de/blog/postings/2025-12-21/0/netbook.jpg

@shinyoukai@neko.laidback.moe But I thought Alpine was one of the good distro’s left. 😢 What’s it doing wrong?

@kiwu@twtxt.net Assembly is usually the most low-level programming language that you can get. Typical programming languages like Python or Go are a thick layer of abstraction over what the CPU actually does, but with Assembler you get to see it all and you get full control. (With lots of caveats and footnotes. 😅)

I’m interested in the boot process, i.e. what exactly happens when you turn on your computer. In that area, using Assembler is a must, because you really need that fine-grained control here.

@kiwu@twtxt.net Finally doing some Assembler again. 😅 Just a tiny little bit at least.

@lyse@lyse.isobeef.org Yeah, well, given that I didn’t need this for such a long time, it’s probably not an essential tool. 😅

I’ve often wanted to have an outline of text documents, though, and tagbar/ctags can do that as well:

https://movq.de/v/3c6d1a13d6/tagbar-md.png

https://movq.de/v/abc58e6d66/tagbar-latex.png

This isn’t as powerful as the “Navigator” tool in StarOffice/LibreOffice (which can be used to rearrange the document), but still pretty useful:

https://www.uninformativ.de/blog/postings/2024-05-23/0/so31.mp4

@lyse@lyse.isobeef.org Awww, 03.jpg. 😍 Yeah, we also had a nice sunset. I was on the road, though, so no photos.

Ooooooooooh! If your .vimrc is as messy as mine, you’ll be pleased to learn that Tagbar can show a sorted list of all key mappings:

https://movq.de/v/0f37d13a01/s.png

🤯

@prologic@twtxt.net It is, yes.

I rewrote all my solutions in Rust (except for day 10 part 2) and these are the runtimes on my i7-3770 from 2013 (this measures CLOCK_PROCESS_CPUTIME_ID, not wallclock):

day01/1 [      00.000501311] Result: 1066
day01/2 [      00.000400298] Result: 6223
day02/1 [      00.000358848] Result: 12586854255
day02/2 [      00.000750711] Result: 17298174201
day03/1 [      00.000106537] Result: 17405
day03/2 [      00.000404632] Result: 171990312704598
day04/1 [      00.000257517] Result: 1626
day04/2 [      00.007495342] Result: 9173
day05/1 [      00.000237212] Result: 505
day05/2 [      00.000142731] Result: 344423158480189
day06/1 [      00.000229629] Result: 4076006202939
day06/2 [      00.000279552] Result: 7903168391557
day07/1 [      00.000204422] Result: 1622
day07/2 [      00.000283816] Result: 10357305916520
day08/1 [      00.029427421] Result: 84968
day08/2 [      00.028089859] Result: 8663467782
day09/1 [      00.000310304] Result: 4764078684
day09/2 [      00.015512554] Result: 1652344888
day10/1 [      00.000796663] Result: 375
day10/2 [      --.---------] Result: 15377 (Z3)
day11/1 [      00.000416804] Result: 753
day11/2 [      00.000660528] Result: 450854305019580
day12/1 [      00.000336081] Result: 577
day12/2 [      00.000000695] Result: no part 2

A little under 90 ms total.

On my Samsung NC10 netbook from 2011 with its Intel Atom N455 at 1.6 GHz:

day01/1 [      00.003771326] Result: 1066
day01/2 [      00.003267317] Result: 6223
day02/1 [      00.003902698] Result: 12586854255
day02/2 [      00.006659479] Result: 17298174201
day03/1 [      00.000747544] Result: 17405
day03/2 [      00.002737587] Result: 171990312704598
day04/1 [      00.001263892] Result: 1626
day04/2 [      00.044985301] Result: 9173
day05/1 [      00.001696761] Result: 505
day05/2 [      00.000978962] Result: 344423158480189
day06/1 [      00.001387660] Result: 4076006202939
day06/2 [      00.001734248] Result: 7903168391557
day07/1 [      00.001295528] Result: 1622
day07/2 [      00.001809659] Result: 10357305916520
day08/1 [      00.277251443] Result: 84968
day08/2 [      00.284359332] Result: 8663467782
day09/1 [      00.003152407] Result: 4764078684
day09/2 [      00.071123459] Result: 1652344888
day10/1 [      00.005279527] Result: 375
day10/2 [      --.---------] Result: 15377 (Z3)
day11/1 [      00.003273342] Result: 753
day11/2 [      00.005139719] Result: 450854305019580
day12/1 [      00.002857552] Result: 577
day12/2 [      00.000004421] Result: no part 2

A little over 700 ms total.

I like this. You get performance that’s more or less in the ballpark of C, but without the footguns.

If your very popular project with lots of stars on GitHub is over 10 years old, and you’re still at a pre-1.0 version because you’re using SemVer and a 1.0 would mean making some kind of commitment and that’s somehow not desirable for you, then I think you’re doing something wrong. 🤔

Got a nice conspiracy theory for you:

https://mastodon.social/@mcc/115670290552252848

Actually wait I just thought about this and realized that the precise timing of the ACTUAL GitHub seed bank, by which I mean the Arctic Code Vault, on 2020-02-02, makes it more or less a perfect snapshot of pre-Copilot GitHub. Also precisely timed before we all got brain damage from COVID. This is the only remaining archive of source code by people with a fully working sense of smell

(Bonus points because the Arctic World Archive is located in Svaldbard and that’s the name of the AI in Stacey Kade’s “Cold Eternity”.)

@prologic@twtxt.net How on earth did you do that so quickly, especially day 10? People were struggling with this a lot. 🤯

@prologic@twtxt.net Jesus, that was quick. 😅

@prologic@twtxt.net How did you optimize that? 🤔

H… Ho… How have I not heard about vim-tagbar before? 😳

https://github.com/preservim/tagbar

Bought more cheap slot plates (with bad reviews and people complaining about the pin order, because I could’nt find a product without such reviews), but those are simply correct now and just work. 🤪

(Well, one part late in the calendar might need floats, depending on how you solve it …)

@prologic@twtxt.net You won’t need floats, but 64 bit integers are mandatory. 😅

@prologic@twtxt.net Whoop, whoop! Nice! And welcome back. 😅

I’m seeing crashes in the 3D subsystem. (Gallium? Glamor? Whatever other Mesa thing they have? No idea.) In the logs I find this:

malloc(): unaligned tcache chunk detected

And that’s why I still care about Rust and want to learn more about it, even though it’s giving me so much headache and I’ve given up so many times. Because Rust currently seems to be the only popular systems programming language that tries to eliminate these error classes.

And of course “the Rust experiment” in the Linux kernel has recently been concluded as “successful”, so that alone is reason enough for me:

https://lwn.net/Articles/1049831/