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Writing an operating system kernel from scratch

(popovicu.com)
304 points Bogdanp | 2 comments | 14 Sep 25 15:44 UTC | HN request time: 0.002s | source
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WD-42 ◴[14 Sep 25 16:55 UTC] No.45241312[source]▶
Zig really is amenable to OS development. And so is RISC-V. I started this same exercise except with x86 first. I quickly got annoyed with all the legacy boilerplate required. RISC-v doesn’t have any of that. It’s so much faster to get up and running. Here’s my bad zig: https://github.com/Fingel/aeros-v
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toast0 ◴[14 Sep 25 17:17 UTC] No.45241487[source]▶
> with x86 first. I quickly got annoyed with all the legacy boilerplate required.

IMHO, if you use a reasonable bootloader, you don't have too much boilerplate. Multiboot loaders do leave you in real mode, and most people want to be in protected mode, so you have to set up some tables and do a jump, but that's not that much boilerplate. There's a bit more stuff if you disable legacy interrupt controllers (which you probably want to) but it seems to me being able to maybe run on a regular pc is worth it (caveats about console interfaces apply... my hobby OS needs bios boot and uses some vga things that I found aren't well supported... serial console is easier, but lots of computers don't have a serial port either)

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ethin ◴[14 Sep 25 18:31 UTC] No.45242144[source]▶
You still have to set up the GDT, TSS, all that other legacy stuff that isn't actually used but it's still there. And if you set it up incorrectly, your punished for it with triple faults and the like, even if nobody even uses anything like the GDT or TSS these days.
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1. WD-42 ◴[14 Sep 25 22:07 UTC] No.45243730{3}[source]▶
Setting up the GDT is exactly the point where I got annoyed enough to see what risc-v was all about.
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2. ethin ◴[14 Sep 25 23:24 UTC] No.45244335[source]▶
Yep, agreed. Don't get me wrong, the Intel/AMD docs are amazing. But even getting the hardware to a usable state (where I define usable as "something that can enumerate PCI devices on the system, even without PCIe") is an absolute pain that really just shouldn't exist. I know that RISC-V ahs it's own tough spots but... IMO it's a lot faster to get up and running with because it doesn't have 10000 execution modes with tons of different requirements you need to do for each mode, and on and on and on and on. (Yes, I'm exaggerating a bit.)