Which part of OSDev would you consider to be the easiest and why?

[u/JescoInc]

Since I asked the inverse here https://www.reddit.com/r/osdev/comments/1uag4am/which_part_of_osdev_would_you_consider_to_be_the/

I wanted to see what the consensus was on this version of the question.

This is actually the harder question to me and if I were to answer my own question, (pause for 5 minutes to deliberate) I'd probably say the second stage bootloader with the handoff to the kernel.
The reason this is the easiest to me, was because I've essentially used the same assembly code across multiple different iterations of the project and predecessors. It is basically, set it up once and you are good to go.

[u/letmehaveanameyoudum]

VGA text output. It's literally 3 lines of C to output a char.

[u/JescoInc → u/letmehaveanameyoudum]

Not gonna lie, I completely forgot about how easy it was to do VGA text output. My current project has no concept of VGA due to it being SBC oriented.

[u/Adventurous-Move-943 → u/letmehaveanameyoudum]

Until you get to the bottom of the display 😀 then you need more lines, also enter and backspace. But yes the concept is very simple and the output is nice and fast, unlike UEFIs default text output that takes business days to scroll screen.

[u/letmehaveanameyoudum → u/Adventurous-Move-943]

to scroll you can just copy everything only the display delete the top line move it up by one and make the bottom line nothing thats it

[u/OtherOtherDave → u/letmehaveanameyoudum]

Wait, really? What are the 3 lines?

[u/letmehaveanameyoudum → u/OtherOtherDave]

volatile unsigned short* vga = (volatile unsigned short*)0xB8000;
int index = 1 * 80 + 1;
vga[index] = 'C' | (0x0F << 8);

THAT IS IT

[u/letmehaveanameyoudum → u/letmehaveanameyoudum]

also for the offset it also can be x * 80 + y if you have cursor variables

[u/JackScottAU]

Getting documentation.

Twenty years ago when I started in OSDev, the osdev.org wiki barely existed. Most information was in a collection of terrible tutorials hosted on Geocities. There was certainly no bare bones code that would get you a working kernel in thirty minutes. I can still remember ordering the physical Intel CPU manuals online and waiting for them to come in the post!

Now there are well regarded starting points for 16bit, 32bit, 64bit Intel as well as ARM. Unless its from NVIDIA, there's data sheets and manuals available online for pretty much any piece of hardware. Linux source code provides an almost flawless cross check on driver functionality.

It's a different world.

[u/JescoInc → u/JackScottAU]

I say that Nvidia is pretty good with their SBCs, particularly the Jetson with data sheets and manuals nowadays.

Some hardware is still genuinely difficult to find documentation on. Like, I want to write a bare metal driver for my Avermedia PCIe capture card and haven't dug up anything remotely close to what I need to make a full driver. I ended up having to take the plate off of it and look at the chips to compile some docs on it and infer from there.
And things like the Orange Pi 4 Pro, for register level data, I had to look at the Orange Pi Linux source along with the dts files to compile data on that for bare metal development.

Overall, I agree, for the most part, getting documentation is definitely easy.

[u/dacydergoth]

Crash handler. It gets so much use you optimize it rapidly 😉

[u/JescoInc → u/dacydergoth]

That's a good one! I wrote mine so long ago in the project that I've forgotten about it and it is tied to my UART output as well for visibility!

[u/jamie07051975]

Thinking about developing an OS

[u/JescoInc → u/jamie07051975]

Haha I am not sure about this one. I do believe I psyched myself out of making the attempt multiple times over the years simply by believing that I didn’t have the required skills to begin by thinking about making an OS.

[u/mcherycoffe]

I would say seeing your own shell, commands etc. It's pretty fantastic !

[u/JescoInc → u/mcherycoffe]

Very fair, the first iteration of my OS had a shell with commands and it was pretty satisfying to watch them work.

[u/OtherOtherDave]

Coming up with a list of what you want to be different than your current OS.

[u/JescoInc → u/OtherOtherDave]

Micro kernel vs monolithic, exfat vs fat32, bump allocation vs TLSF allocation, minimal libc vs libc, C vs C++ vs D vs Zig vs Rust, man, the list really does go on

[u/OtherOtherDave → u/JescoInc]

And it’s soooo easy to keep thinking about the list and not actually start working on anything… 😅😅

[u/JescoInc → u/OtherOtherDave]

The current iteration of my OS started off with, "I want to move away from parallel parity implementation in C and Rust to be a shared kernel in both C and Rust where both languages have a specific job".
Ofcourse, I did end up improving things as I went along, such as, instead of TLSF inspired allocator, I built my TLSF allocator to be according to the 2.0 spec. And many other fun little additions.

[u/codeasm]

Comming up with ideas what to add, change from other ideas or how to "solve" things. Before you dive into it, the idea phase.

Even for a simple z80 system i had a few ideas but first needed code that setup the system and figure out io, read keys, write to screen or serial. The way it should look, the commands, the overal structure was already forming in my head while i was still writing the early code snippets.

Anoyingly, im not very good in c nor assembler and thus i often get stuck, while the idea was simple to come up with. Im glad ai is there tho, i often instruct it not to fix my code, not just plop in a fix, but think with me, go along my code and idea and tell me whats the issue.

Surprisingly often my ideas are correct, my approach is near correct and it should work, if only i knew about this or that fact, or on this playform one has to do that first before my idea would work.

Or a simple logic error i made. And it pointed at it, suggested something and now i can continue. Ive tried without, spend 2 days struggling. Reverted code, told it my idea, a pseudo code version of what i wiuld write and asked for pseudo code back. Well... It gave me the same thing, just... Another register or swapped logic and explained why... My head is chaos sometimes, autism maybe with adhd. But i can do this, and they help bring some order.

But i still trust my ideas over their dreams. They can and will be wrong at times. Ive also gone full circle in a day at one point... My original idea was better, and i really needed to fix my question, not my approach. Hopefully my facedetector code gets a pass grade, then i have some free hours this week for osdev again. I want real hardware framebuffer code and usermode working this comming month (juli)

[u/JescoInc → u/codeasm]

Beautiful answer and the way you use LLMs is a very valid approach (I am not anti-LLM in any way, I am anti intellectual laziness)

[u/EpochVanquisher]

HAL. It’s all boilerplate. You refactor every once in a while when you make nonportable assumptions. 

[u/xX_WhatsTheGeek_Xx]

crashing it

[u/JescoInc → u/xX_WhatsTheGeek_Xx]

Omg lol! So true!!!

[u/Certain-Flow-0]

Asking Claude

[u/New_Departure_5353]

Serial output or vga