movq

www.uninformativ.de

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Recent twts from movq
In-reply-to » @lyse I can tell you this right now, writing assembly / machine code is fucking hard work™ 😓 I'm sure @movq can affirm 🤣 And when it all goes to shit™ (which it does often), man is debugging fucking hard as hell! Without debug symbols I can't use the regular tools like lldb or gdb 😂

@prologic@twtxt.net Debugging this stuff on bare metal hardware (without an underlying OS) is a nightmare. 🤣

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In-reply-to » Trying to come up with a name for a new project and every name is already taken. 🤣 The internet is full!

@lyse@lyse.isobeef.org I’m toying with the idea of making a widget/window system on top of Python’s ncurses. I’ve never really been happy with the existing ones (like urwid, textual, pytermgui, …). I mean, they’re not horrible, it’s mostly the performance that’s bugging me – I don’t want to wait an entire second for a terminal program to start up.

Not sure if I’ll actually see it through, though. Unicode makes this kind of thing extremely hard. 🫤

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In-reply-to » Hmmm I need to figure out a way to reduce the no. of lines of code / complexity of the ARM64 native code emitter for mu (µ). It's insane really, it's a whopping ~6k SLOC, the next biggest source file is the compiler at only ~800 SLOC 🤔

@prologic@twtxt.net This is a really cool project, that’s for sure. 👌

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In-reply-to » 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).

@prologic@twtxt.net Oh! 🤔

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In-reply-to » 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).

@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. 😃

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In-reply-to » 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).

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

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

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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.)

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In-reply-to » Wow, @movq, so many tables. No idea what I expected (I'm totally clueless on this low-level stuff), but that was quite an interesting surprise to me. https://www.uninformativ.de/blog/postings/2025-12-21/0/POSTING-en.html

@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.

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In-reply-to » Wow, @movq, so many tables. No idea what I expected (I'm totally clueless on this low-level stuff), but that was quite an interesting surprise to me. https://www.uninformativ.de/blog/postings/2025-12-21/0/POSTING-en.html

@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

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In-reply-to » @movq wow! what is assembler?

@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.

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In-reply-to » H… Ho… How have I not heard about vim-tagbar before? 😳

@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

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In-reply-to » Advent of Code 2025 starts tomorrow. 🥳🎄

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.

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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. 🤔

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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”.)

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