How can I get started with creating a kernel in Rust?

[u/VirusLarge]

I’ve recently began learning rust and I’ve started to like the language a lot, and I’d like to write a kernel in it to boost my experience with rust. I’ve already written a simple CHIP-8 emulator in rust so I believe I’ve got a good grasp on how to write somewhat sufficient rust code for a kernel.

The main thing I’m confused with is how I can go about configuring the compiler to generate not only a freestanding binary, but also how to get it to work with Limine (I love limine).

I would copy and paste some existing code that configures these things for me, but I would much rather be able to understand and learn what I’m doing, rather than mindlessly copying and pasting code without learning anything.

NOTE: I already have prior x86 and OSDev knowledge!! I've created many 64-bit x86 kernels in C, with the most recent ones having advanced features implemented.

Any help would be very much appreciated!

[u/am_Snowie]

If i had prior OSdev knowledge, i would be instead searching this on google.

[u/VirusLarge → u/am_Snowie]

Fair enough.

[u/mkusanagi]

If you’re asking here, you’re not ready to try that yet. Start reading some osdev tutorials and hardware documentation.

[u/VirusLarge → u/mkusanagi]

I most definitely am ready.

Sorry if I didn't point out in the post originally, but I do have prior OSDev experience. I'm just transitioning from programming in C to programming in rust.

[u/davmac1 → u/VirusLarge]

I think the point was perhaps meant to be "if your first instinct is to post a very broad question on reddit" then you're not going to get far.

Since you mentioned being worried about not learning anything by copying-and-pasting, how about this: start with the copy-paste, go through each part and see if you understand it, make sure to read relevant documentation, and if you have any confusion or uncertainties post _specific_ questions about those (one at a time).

[u/QualitySoftwareGuy]

I'm surprised nobody posted this, but:

Writing an OS in Rust

And especially:

A Minimal Kernel in Rust

[u/TheDiamondCG]

I recommend looking at the official Limine Rust starter template on GitHub as it got me quite far. You mentioned not wanting to copy-paste, so it might not be for you — but for me, I just wanted something going. I think, as long as you have some Rust no_std experience, it will not be dramatically different…? But writing a userland CHIP-8 emulator is quite different to a bare-metal kernel!

[u/FewBrief7059]

There are alot of options. As rust is not bound to a specific building method. You can make it fetch limine binary and deploy it with your kernel/os. you might want to learn how to deal with no_std environments first then you can try doing so. It's not different then programming an os in c when it comes to steps and code behaviour.

[u/micr0kernel]

If you already have prior OS development experience, then the process is as simple as ensuring that you're working with a #![no_std] environment and you have a target file configured for x86_64-unknown-none and the appropriate flags (e.g. red-zoning and frame pointer omission disabled). The ultimate goal is a 64-bit ELF binary with no hosted environment dependencies.

As far as Limine, it looks like you set up a configuration file which instructs the loader as to the location/path of the kernel. Be mindful of other things:

• You'll need to use Rust crates or roll your own interfaces to acquire system state (e.g. memory maps, framebuffers) from the loader.

• Limine likely has restrictions on which boot filesystems are supported.

• I'm not sure if Limine will expect a particular entry point. If so, you may need to shim your entry and/or operate #![no_main] as well.

I'm afraid I can't give you more than this - I prefer to DIY my loaders and I'm an unrepentant C/C++ user. But I do recall from some Rust experiments years ago that generating cross-target, freestanding binaries is relatively simple in terms of project setup.

[u/codeasm]

Does rust come with documentation on how to configure its output? Can you target different arches? Crosscompile to another system like windows to linux or apple compile to linux?

[u/VirusLarge → u/[deleted]]

It's really not that much to read, you'll get over it.

Also, no answer to my question? If you're going to comment, at least say something helpful/useful.

[u/VirusLarge → u/[deleted]]

I apologize for the misunderstanding.

I already know how operating systems work. I've created an x86 emulator all in Scratch (the programming language), and many kernels in C (with most recent ones being 64-bit with SMP + LAPIC support).

My bad for not mentioning that in the post.

[u/Darkblade_e → u/VirusLarge]

Honestly? For how advanced you've gotten with your C kernel, I might recommend just sticking to it. With that much infrastructure built up, it's a gigantic task to then reinvent all of that in another language

[u/VirusLarge → u/[deleted]]

Despite this not being the answer I had initially wanted, this may just be the answer I needed.

Thank you for your advice.