JCM

https://wafrn.jcm.re/fediverse/blog/jcm

Hello World!

I am a Computer Engineering student in Berlin and do low-level programming, cursed C++ projects, FPGA stuff, and self-hosting in my free time :3

I absolutely love and adore my cute girlfriend [@xcyndi.bsky.social](https://wafrn.jcm.re/blog/@xcyndi.bsky.social?id=75027eb0-32ec-4ce1-bcb1-72508a6f2f15 ) / Cyndi~ (npub16ev…x36r) !

I like modern C++, Vulkan, WebAssembly, VHDL, FPGAs, SBCs, Kubernetes, game modding, Ganqing Impact, and Cyberpunk 2077.

Feel free to refer to this one as "sheepy" (it/its) and in 3rd person sometimes. It enjoys it, but isn't quite sure about it.

GitHug: https://git.jcm.re/jcm
GitHub (less cute): https://github.com/JnCrMx
GPG: 7B839F0DA64069DD7832BB802F536DE3E9EC3AD8
Discord: _jcm_
Signal: jcm.86
(currently unused) HAM radio call sign: DC7JCM
Website: https://jcm.pet/
Pronouns: he/him or sheepy/it/its (3pp) because I wanna see how it feels
Matrix: @jcm:jcm.re

Public Key

npub1ga9jyqm9p6qpmlnp6l4ffl79cv0gdptlqrr686zr8dmmy7zc49est5hldc

NIP-05 Address

jcm_at_wafrn.jcm.re@momostr.pink

Profile Code

nprofile1qqsywjezqdjsaqqalesa0655llzux85xs4lsp3arappnkaaj0pv2jucprpmhxue69uhhyetvv9ujumt0d4hhxarj9ecxjmntrl58yk

Publishing to

relay.momostr.pink

Author Public Key

npub1ga9jyqm9p6qpmlnp6l4ffl79cv0gdptlqrr686zr8dmmy7zc49est5hldc

Show more details

Published at

2026-10-06T01:33:30Z

Kind type

0 Metadata

Event JSON

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Last Notes

2026-09-11 14:35:16 UTC

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All real life inputs as finite, therefore all algorithms are O(1) for any case that actually matters. :P

2026-09-11 14:33:28 UTC

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If you are determining big O complexity, it doesn't really matter, because the access time is basically bounded by a constant regardless of n and access pattern (we could argue about it being different on *weird* custom architectures, but then we also have to consider lots of other stuff we don't wanna).
If you're trying to estimate the *real* duration an algorithm will take, it's a different story of course. :P

2026-09-10 03:36:16 UTC

I hate QML… (could just be my fault tho for my UI being super duper messy T_T)

2026-09-09 15:12:04 UTC

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As a TA myself, this is so incredibly sad 😢
Are they replacing just some of their TAs or literally all of them in that course?

2026-09-08 13:05:28 UTC

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The question is just if whoever is grading isn't too lazy to even attempt to figure it out 😅
But maybe your university is better than mine when it comes to that.
Also, I really gotta learn Meson on day, it always seemed nicer than CMake to me, but I've never had the motivation to actually use it for a project and learn it (especially since many of the dependencies I frequently use mainly work well with CMake).

2026-09-08 01:05:00 UTC

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Just make sure whoever is grading your work follows the same approach :P
When I "grade" my students' assignments, I personally never deduct points for technically correct code that fails due to incompetent tools (sadly that makes this code very painful to actually test).
But I know that at my university a ton of TAs and professors don't care at all, just run some automatic test scripts and give 0 points if they fail ~_~

2026-09-05 16:41:28 UTC

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Aaaaah, so like storage systems, items sorters, shulker (un)loaders, and stuff like that? :D
That's cool!

2026-09-04 21:01:33 UTC

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Is that a real life technology thing or a Minecraft thing? 😅

2026-09-01 18:09:27 UTC

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Maybe there's a Nextcloud folder in Dolphin or something?

2026-08-27 19:57:15 UTC

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If it's for the Nvidia Jetson Nano, maybe a MIPI CSI camera could be a solution? It will only add one additional camera tho…

2026-08-27 19:38:30 UTC

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Time for case-insensitive programming languages then :P

2026-08-24 04:51:31 UTC

I love seeing/reading about other people's device naming schemes :D

2026-08-24 04:42:55 UTC

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I think you can just mount your root filesystem to s temporary mount point after the reboot, delete the leftover files from the old /tmp (which would overwise be hidden by the tmpfs mount), and unmount it again.
(assuming you declare the tmpfs in fstab, so it will be mounted on boot)

2026-08-24 04:33:51 UTC

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Until you use frameworks and Next.js decides to implement the run arbitrary code endpoint for you :P
[https://www.cve.org/CVERecord?id=CVE-2025-55182](https://www.cve.org/CVERecord?id=CVE-2025-55182)

2026-08-24 04:32:30 UTC

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C++ has the unique security property that it can fuck you over without the need for an attacker to begin with :3

2026-08-24 04:27:45 UTC

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Sort of. Security is hard to measure sadly, so we had to bullshit our way through.
We ended up deploying a service mesh with restrictive permissions limiting which service can communicate with which other services and some (imo kinda shitty) intrusion detection systems.
It's not my proudest work tbh, mostly because I don't think that the intrusion detection (which I deployed and configured) is particularly good or effective…
But hey, I'm done with the course and my grade isn't terrible. I have other better courses to pour my heart into :D

2026-08-24 04:22:32 UTC

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xD
Luckily not actually. We basically got an existing microservice architectures and had to refactor the architecture itself (so not even much code editing) to improve different aspects (my group had security, other groups stuff like energy efficiency, AI integration, resilience, etc.).
So I was mostly writing Terraform code and praying that I don't overspend on Google Cloud on accident :P

2026-08-24 04:19:59 UTC

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I mean, that would work xD
Just make sure to remove it from all necessary folders. I think many programs won't be happy being unable to write cache, logs, etc

2026-08-24 04:18:21 UTC

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I'll be honest, I didn't care enough about that specific course to attempt to enforce any kind of policy in my group.
I did my part and I was happy.
Overall the course wasn't the greatest…
I shouldn't have had high expectations in "Cloud native architecture and engineering" taught by the same department teaching about "Blockchain technologies" xD

2026-08-24 04:14:16 UTC

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The `i` attribute only affects one directory. Child directories are not affected. Existing subdirectories are also fine.
It's basically forcing the directory (and only the directory itself) to be read-only.

2026-08-24 04:12:54 UTC

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Introducing `solofs`: Every new directory needs personal approval by @solonovamax@tech.lgbt.
```
mkdir.solo Project1/abc --reason "pls pls pls allow me 🥺"
```

2026-08-24 04:09:32 UTC

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Oh… It's those kind of teammates… Oof…
I've recently had a group project with one person using Claude for everything. The codebase really doesn't turn out nice in my experience.
Still better than the group who did "In order to save energy we asked Claude to rewrite the entire given codebase in Rust. It's more energy efficient now, but doesn't always work anymore."…

2026-08-24 04:06:44 UTC

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No need to change attributes on the subdirectories.
You simply cannot create subdirectories (and many other things) as long as `i` is set. You can however write into subdirectories no problem. Oh, and you can also mount to the directory still, which can be really useful sometimes.
```
jcm@v:~$ mkdir test
jcm@v:~$ cd test
jcm@v:~/test$ mkdir a
jcm@v:~/test$ sudo chattr +i .
[sudo: authenticate] Password:
jcm@v:~/test$ touch a/file
jcm@v:~/test$ mkdir b
mkdir: Permission denied
jcm@v:~/test$ sudo mkdir b
mkdir: Permission denied
jcm@v:~/test$ sudo chattr -i .
jcm@v:~/test$ mkdir b
jcm@v:~/test$
```

2026-08-24 04:02:13 UTC

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If you wanna do a bit of low effort trolling, so a `chattr +i` on the directory in which you don't want unauthorized subdirectories and see how long it takes your team to figure it out :P

2026-08-24 03:59:11 UTC

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That's so evil xD
I love it! :D
(But probably don't do it, it sounds like a recipe for loving important work one day before a deadline 😅)

2026-08-22 02:28:46 UTC

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H-Hey! Is it really THAT obvious? >////<

2026-08-22 02:09:57 UTC

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>///////<
https://media.wafrn.jcm.re//1787362524033_38a4204f22add20f58dcfc67c5844b066d83beddfe3c59683ef82628cdcb1e8a_processed.webp

2026-08-21 05:51:39 UTC

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😱
S-stop scaring me even more!!!
Telling `<` (the operator), `<<` (the other operator), and `<...>` (the template brackets) apart already seems super challenging to me.

2026-08-21 05:44:22 UTC

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S-so scaaaaary!
Even the thought of parsing C++ at all is nightmare fuel already!

2026-08-14 23:50:14 UTC

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I'm not so good in JS, but won't this turn big numbers intentionally stored as strings into BigInts too? Or is that whatever in JS? 😅

2026-08-09 22:45:16 UTC

After seeing so many posts about it today, I do really wonder what being shocked feels like…

2026-08-09 17:50:16 UTC

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My idea was for something like this to do the biting :D
https://media.wafrn.jcm.re//1786297787828_4b26ad88fcdcffad409d22049c4ab844dfd9360c4ca824e7c79fbe0ce181da4d_processed.webp

2026-08-09 15:56:51 UTC

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I'm tempted to do exactly that once I'm home again and have time for it (maybe smaller and wearable tho)

2026-08-06 17:47:33 UTC

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Yeah…
What the hell is `String.raw` in this case even?!
A special function?! Some extra privileged syntax?! Can I implement it myself from scratch if I want to?!

2026-07-31 19:18:02 UTC

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DHL (German package carrier) charges 15.99€ (=25.85 CAD) for the smallest package (35x25x3 cm up to 2kg), but without tracking or insurance.
Bigger package with tracking and insurance costs 26.49€ (=42.82 CAD).
Here's what I have and no longer need:
- 3x ESP32-S3-DevKitC-1
- 1x ESP32-H2-DevKitM-1 (has some fancy secure boot stuff I never experimented with)
- 1x Sipeed Maixduino (some RISC-V stuff, not sure how well the toolchain works nowadays) with display, camera and 3D printed case
- 1x loose NodeMCU ESP8266 dev board
- 1x Arduino MKR Vidor 4000 (if you want to get into FPGA development), this one has an Arduino and an Intel FPGA (if you think embedded toolchains are bad, FPGA toolchains are even worse), it is fairly powerful and can output HDMI
- 1x LilyGO T-FPGA (includes ESP32-S3, also mainly for FPGA stuff) with the expansion board, this one has a Gowin FPGA, which is less powerful, but has a fairly good open source toolchain (not a pain)
- 1x M5Stick Cplus 1.1 (what a name!), has ESP32, display and button
I also still have plenty of sensors, Atmel microcontrollers (some Attiny24, some Atmega), a few IO expander ICs, some digitally controllable resistors, digitally controllable analog muxes, some servo motors, some more loose ESP32 dev boards, and some other stuff at my family's house (so I cannot give you a full list right now).
But the sensors are mostly cheap sensors from a kit and are really random, stuff like flame sensors, ultrasonic distance sensors, lasers, photodiodes, etc. They are all on boards with headers, so you can use jumper cables to connect them.
I also have a ROCK Pi 4 and an ODROID M1, that I don't have a use for. But they have metal heatsinks attached, and would drive up the package weight ofc.

2026-07-31 19:07:08 UTC

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I wish mailing stuff to Canada was cheaper :/
I have so many unused/never used ESP32 devkits/random sensors/other stuff lying around and this would have been the perfect opportunity to give them away

2026-07-31 18:41:17 UTC

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Yeah… I have one project for which I'm more or less forced to work with platformio and it is the biggest pain ever. 😭

2026-07-31 04:17:57 UTC

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No more file type restrictions! I wanna be able to upload ANY file.
Think about the possibilities:
- CI artifacts as Fedi posts
- sharing totally trustworthy executables
- attaching scientific papers directly as PDFs¹
- integration with Forgejo once it does federation properly to submit pull requests
- sharing /dev/random
¹ Wafrn actually allows PDF uploads, which is awesome. But so far I've only used it for randomly posting my Bachelor's Thesis as a test. Maybe I'll find more use for it eventually.

2026-06-19 09:53:38 UTC

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May I ask what you dislike about working with Docker/Podman? Not trying to argue or convince you, I'm just curious :D

2026-06-19 03:25:49 UTC

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No need to emulate anything. The container (I personally use Podman for such stuff) is just used to get a disposable Ubuntu build environment.
It still runs the native apt, native compiler, native linker, etc.
It can be useful if you want to make sure all the versions match up.
My usual process:
- Create Ubuntu container with project mounted in it
- Install host tools
- Add foreign architecture
- Install target libraries
- Build
- Store build artifacts in mount
This allows easy incremental builds with a very standardized disposable environment.

2026-06-19 02:17:12 UTC

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If you just want the sysroot without any bells and whistles, you can also use `debootstrap` (in the Arch repositories btw):
```
sudo debootstrap --arch=arm64 --variant=minbase --include=libstdc++-14-dev,other,packages,you,need noble /path/to/sysroot
```

2026-06-19 01:49:57 UTC

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Some examples:
- [Dockerfile for a relatively complex C++ project](https://github.com/JnCrMx/cutie-logs/blob/main/Dockerfile)
- [CI flow for a complex C++ project with cross-compiled AppImage generation](https://github.com/JnCrMx/xmbshell/blob/main/.woodpecker/build.yml)
- [Bonus: CI flow for Windows in the same project](https://github.com/JnCrMx/xmbshell/blob/main/.woodpecker/windows.yml)
- [Dockerfile for a simple C++ project](https://git.jcm.re/jcm/tuvpn/src/branch/main/Dockerfile)
- [CI flow for a simple C++ project](https://git.jcm.re/jcm/gpgfs/src/branch/main/.woodpecker/build.yaml)

2026-06-19 01:41:24 UTC

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What I like to do when building the other way around (x86_64 target and arm64 host) is just adding the architecture I build for as a foreign architecture (plus the correct repos) and then install all the required libraries directly (by specifying `:arm64`).
However, I of course do that in a disposable container, since it basically turns the system into a complete mess.

2026-06-14 04:29:10 UTC

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To give a bit more context:
GCC optimizes the function into a `return true` in both C and C++ mode.
Clang however does this optimization only in C++ mode and outputs the "normal" code in C mode.
My guess to why this is the case:
The C++ standard guarantees forward progress, so any infinite execution of code without ever making progress can be assumed to be impossible.
The C standard only guarantees loops to eventually terminate or make "progress".
This isn't a loop tho, it's recursion. So my guess is that Clang is sticking closer to the wording of the standard and therefore doesn't optimize recursion in the same way it would optimize loops.
However, I'd love to be corrected by someone more familiar with C and C++ standards if my guess is wrong.

2026-06-14 04:21:54 UTC

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This is probably my new favorite example of forward progress/infinite loop UB.
It's so incredibly interesting, since different compilers produce different code depending on if they are in C or in C++ mode.

2026-05-22 17:19:07 UTC

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OpenSCAD my beloved 😍

2026-05-04 12:56:50 UTC

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In Berlin? :O
For free? :O
OMG, this is amazing! :waffy_heart: :waffy_party:

2026-04-29 17:29:25 UTC

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What stops those repeaters from tracking you?
Even with Tor a big provider could easily analyze bandwidth and timing of calls to gather metadata and then correlate it with location information.
And then there is billing and access control…

2026-04-29 17:18:39 UTC

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Wouldn't a mesh network kind of limit the speed extremely and also be very unreliable or straight up unavailable if there isn't enough other nodes next to you?

2026-04-29 17:10:19 UTC

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How would the first option work? /gen
Like, how would the carrier know where to route an incoming phone call to?

2026-04-09 03:50:32 UTC

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Thank you for the suggestions! :D
Setting `-Xmx` and `-Xms` is already done by the Docker images based on the `MEMORY` environment variable: [https://git.jcm.re/jcm/coder-templates/src/commit/9fb432ffb8363323686c6697c4af5b00a61797ff/minecraft-server/main.tf#L728](https://git.jcm.re/jcm/coder-templates/src/commit/9fb432ffb8363323686c6697c4af5b00a61797ff/minecraft-server/main.tf#L728)
The other suggestions I will implement tomorrow ^^
#L728

2026-04-09 03:22:26 UTC

I ended up creating a Coder template for it: [https://git.jcm.re/jcm/coder-templates/src/branch/main/minecraft-server/main.tf](https://git.jcm.re/jcm/coder-templates/src/branch/main/minecraft-server/main.tf)
It is still missing a lot of server.properties, but I am going to add them later as needed.
[itzg/mc-router](https://github.com/itzg/mc-router) and [qumine/ingress-controller](https://github.com/qumine/ingress-controller) are really amazing for automatically routing Minecraft Java edition connections to the right server! :D
#self-hosting #selfhosted #Kubernetes #Minecraft #Coder
https://media.wafrn.jcm.re//1775704896212_82a63b9fb072dec18a60f5b17337879bfa0bf78d_processed.webp
https://media.wafrn.jcm.re//1775704918141_3f126875acbeb93b7516a4546651ef3a45ef0e9e_processed.webp
https://media.wafrn.jcm.re//1775705003579_6dfb366b022b92e60d2d9126f951f0513034b9f7_processed.webp
#note1af3…kaks

2026-04-07 04:06:51 UTC

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Sadly Pterodactyl [explicitly denied](https://github.com/pterodactyl/panel/issues/4406#issuecomment-2639458001) Kubernetes support :(
There is [kubectyl](https://github.com/kubectyl/kuber), but it is archived and seemingly never left pre-release status.

2026-04-05 16:19:06 UTC

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Ideally some user friendly no-code Web UI.
For example the following flow:
- I click "New server"
- I enter name, version, mods, etc.
- The system automatically creates a Deployment, PVC, Service, etc.
- I can administer my server (start, stop, backup, delete, console access, etc.) in the Web UI
I think it might be possible to create something like this with Coder (which I'm already running), but Coder is very coding focused (duh), which is why I'm wondering if there is something more native for game servers.

2026-04-05 16:11:11 UTC

Does anyone know a self-host able Minecraft server (or maybe even general game server) administration tool (so something like Pterodactyl) that works with Kubernetes?
#selfhosted #Kubernetes #self-hosting

2026-03-21 07:43:19 UTC

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Sure!
Some small questions about it tho: Should I prepare some slides? English or German? How much time should it take?

2026-03-19 16:07:22 UTC

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Alrighty!
Then feel free to let me know once you have a date for it. :D

2026-03-19 15:38:30 UTC

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When would that meetup be next? If I have the time, I'd love to participate!

2026-03-16 21:13:04 UTC

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That does sound cool!
However, I don't know how much Fediverse-related stuff I would be able to say. Most of that is handled by Wafrn. Wafbuntu does very little more than fetching and displaying the data Wafrn provides.
Also, Wafbuntu is still far from feature complete. You can mostly just view posts, interact with them and create text-only posts.

2026-03-16 17:42:00 UTC

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Those are the ones I found in my backup of my Ubuntu Touch. They are a tiny bit out of date, but not too much.
I don't use Ubuntu Touch anymore (because I encountered some issues and too many annoyances), so development on Wafbuntu slowed down quite a bit.
However, I still plan to implement a few more features once I get the time to do so.
https://media.wafrn.jcm.re//1773682652068_9016c923fa78442f23f01fe6b1572363dcef725e_processed.webp
https://media.wafrn.jcm.re//1773682663039_3e1cd4c627429363633ed7bbad770d4154027559_processed.webp
https://media.wafrn.jcm.re//1773682663345_fcfcfef8cab25992bc44f71a57bb0b48deaf9e30_processed.webp
https://media.wafrn.jcm.re//1773682682634_91394eedd3e6f2075ad58c62810af40c952e83cb_processed.webp
https://media.wafrn.jcm.re//1773682682771_71c92b585c70b78782380a828a03e30598643321_processed.webp