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John Carmack's arguments against building a custom XR OS at Meta

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520 points OlympicMarmoto | 1 comments | 29 Aug 25 16:45 UTC | HN request time: 0s | source
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jnwatson ◴[29 Aug 25 17:46 UTC] No.45067216[source]▶
I've written a lot of low level software, BSPs, and most of an OS, and the main reason to not write your own OS these days is silicon vendors. Back in the day, they would provide you a spec detailed enough that you could feasibly write your own drivers.

These days, you get a medium-level description and a Linux driver of questionable quality. Part of this is just laziness, but mostly this is a function of complexity. Modern hardware is just so complicated it would take a long time to completely document, and even longer to write a driver for.

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bbarnett ◴[29 Aug 25 21:03 UTC] No.45069349[source]▶
Modern hardware is just so complicated it would take a long time to completely document, and even longer to write a driver for.

That's what's claimed. That's what people say, yet it's just an excuse. I've heard the same sort of excuse people have, after they write a massive codebase, then say "Oops, sorry, didn't get around to documenting it".

And no, hardware is not more difficult than software to document.

If the system is complex, there's more need to document, just as with a huge codebase. On their end, they have new employees to train up, and they have to manage testing. So any excuse that silicon vendors have to deal with such immense complexity? My violin plays for them.

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makeitdouble ◴[29 Aug 25 22:57 UTC] No.45070341[source]▶
> "Oops, sorry, didn't get around to documenting it".

That's obviously the wrong message. They should say "Go ask the engineering VP to get us off any other projects for another cycle while we're writing 'satisfying' documentation".

Extensive documentation comes at a price few companies are willing to pay (and that's not just a matter of resources. Look at Apple's documentation)

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MathMonkeyMan ◴[30 Aug 25 00:55 UTC] No.45071005{3}[source]▶
I write documentation as I'm writing the code. In my opinion, the code is only as good as its documentation -- they're two parts of the same thing. It's mostly comments at the top of files, and sometimes a markdown file in the same directory.

This way, good documentation is priced into my estimate for the project. I don't have a work item "spend a few days documenting." Nope, if I'm doing a foo then that includes documenting a foo at the same time.

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1. PeterStuer ◴[30 Aug 25 07:23 UTC] No.45072618{4}[source]▶
Documenting what is there usually is not the hard part (and AI is getting pretty good at that part btw).

Documenting how to use or interact with it in a specific context, which often includes perspectives on interactions with other components, or e.g. protocols not explicit in the code, deciding where to draw the lines of what can assumed trivial common knowledge and what should be specified or explicitly not specified without notices not to rely on these etc. , that is a different thing.

If it wasn't, then truly as they used to say, the source code would be it's own best documentation (I am a big fan of programming for readability, but even the best readable code, while it will be correct and up to date, will never be enough nor the best for all)