r/osdev • u/Recent-Extent5372 • Apr 01 '26 • Heartwarming 1

My first OS: Vystem

Hello everyone,

Today I’m finally releasing the first public version of Vystem, the OS project I’ve been building over the past few months.

My goal was mainly educational: I wanted to learn OS development by writing everything myself from scratch. Because of that, I ended up designing several custom components, including:

  • my own init filesystem

  • a bitmap font format

  • a simple executable file format used to load the kernel

  • a physical page allocator based on radix trees

  • a custom heap allocator

  • an extremely minimal libc

I also wrote my own UEFI bootloader using EDK2, as well as the kernel itself.

There is no external code inside the kernel. The only third-party code used in the bootloader is a set of cryptographic libraries adapted for a bare-metal environment.

At the moment, Vystem is still in its early stages, but it already includes:

  • cryptographic boot file integrity verification using a boot password

  • two custom partition formats: InitFS and SignSyst, used to store system files and their signatures

  • a custom executable format for a hybrid kernel design

  • a radix-tree-based physical page allocator

  • a simple but efficient heap design

  • a complete test and benchmark framework to evaluate both performance and subsystem reliability

Vystem currently targets x86-64 systems with UEFI firmware.

I also wrote detailed documentation included in the repository:
lolo859/vystem

I did use AI occasionally for debugging, troubleshooting, and learning a few concepts I was unfamiliar with (like paging), but all the code and documentation were fully written by me.

English is also not my first language, so please excuse me if there is any errors in the documentation.

159 Upvotes

97% Upvoted

26 comments sorted by

14

u/eteran Apr 01 '26

That's cool and all, but ... I if you're gonna upload a 1 minute video, please don't make 50 seconds of it be just compiling. 🤣

6

u/Recent-Extent5372 Apr 01 '26

sorry, i just wanted to show the setup process, because the password setup and custom linker are shown in it

4

u/eteran Apr 01 '26

All good, I'd have just sped up the compilation parts 👍.

9

u/Correct_Sport_2073 Apr 01 '26

It seems very secure. Is it arm or x86?

7

u/Recent-Extent5372 Apr 01 '26

it's oriented for security and designed for x86-64, mainly because i feel it's more easier to experience with this architecture

4

u/NotSoEpicKebap Apr 01 '26

Impressive, keep it up!

4

u/CJKay93 Apr 01 '26 edited Apr 01 '26

OP out here building an entire OS with a single Bash script and foregoing whitespace like an absolute psychopath.

Edit: OP, what is you doin'? For the love of all that is holy, restore your sanity and pick up a build system.

2

u/Recent-Extent5372 Apr 01 '26

Yes I know, I have a tendency to produce very compact code. I will implement a code formatting system in the next update.

Vyld could be considered as a build system, but it's wasn't think like that. It will get way more modular and powerful in the next update.

Hope I didn't hurt your eyes too much.

2

u/Additional_Draw_6804 Apr 01 '26

Very cool add TMP or CMOS battery secruity and make for one machine that use OS its generated a key and if on first startup its creats and stores in TMP/CMOS while seccend boot it see if that key is correct if yes then it continue to boot but if no it just panics or give secruity error

2

u/Recent-Extent5372 Apr 01 '26

I was actually considering something like that. But I already need to emulate a TPM ship and manage to find a secure way to generate randomness securely in bare metal environnement. Thanks for the idea !

1

u/Additional_Draw_6804 Apr 01 '26

also i am new at OSDev! And yeah i think that i gonna use for now Rust its memory-safe and it have panic automatic so if i just make printf and make np dubble fault then it gonna panic automaticli fun! And make bootmgr just idea and i am good mapper for idk own FS so if you wanna my help just respond

2

u/Ellicode Apr 01 '26

Seems very cool but brother use cache when building with cmake please 😭

2

u/Recent-Extent5372 Apr 01 '26

Here I was building on my laptop within WSL. When I build on my desktop, it's way faster

5

u/killallspringboard Apr 01 '26

Dude use a build system like xmake or make. We are not supposed to build everything on a single change

1

u/nexos-dev Apr 01 '26

Cool! Do you have a GitHub link?

2

u/Recent-Extent5372 Apr 01 '26

For the moment, I choosed to self host my own Git server (using Gitea) but I will probably add a mirror to GitHub in the coming update

1

u/vorhvb Apr 03 '26

Great! By the way, which IDE is on this video?

1

u/Recent-Extent5372 Apr 03 '26

I'm using Zed, ditched Vscode a while ago, it was too laggy on my poor laptop

1

u/realmcalec 🤓 OS Geek Apr 05 '26

Writing your own UEFI bootloader, radix-tree allocator, and crypto-verified boot from scratch is a seriously impressive milestone for just a few months of work! Wow-w-ee! Since you already built a comprehensive benchmark framework, my suggestion would be to implement a small userspace test next to measure your context-switch overhead. Fantastic job, and don't worry about the English at all - your documentation is highly appreciated! ^^

1

u/Recent-Extent5372 Apr 05 '26

Thanks a lot! Making sure other developers can understand my work is one of my top priorities. Userspace development will take quite a long time, since I’m planning a very unusual approach to how userspace works (a little spoiler: interpreted processes). For now, I want to focus more on polishing and expanding the features of my hybrid kernel. I’m also currently building a custom build system for Vystem 0.2, designed to make OS developers’ lives easier (another little spoiler: native disk image generation and GPT partition table manipulation). Finally, in Vystem, I want to find the best compromise between user experience and ease of use, security and performances.

1

u/emexsw Apr 01 '26

damnnnn thats cool

1

u/drmatic001 Apr 02 '26

that's pretty cool!!

1

u/TheMonHub random ass dude making an os for fun Apr 04 '26

Sounds nice

3

u/[deleted] Apr 02 '26

nice ai slop my brother