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

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520 points OlympicMarmoto | 2 comments | 29 Aug 25 16:45 UTC | HN request time: 0s | source
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dmazzoni ◴[30 Aug 25 00:06 UTC] No.45070781[source]▶
I was at Google when the Flutter team started building Fuchsia.

They had amazing talent. Seriously, some of the most brilliant engineers I've worked with.

They had a huge team. Hundreds of people.

It was so ambitious.

But it seemed like such a terrible idea from the start. Nobody was ever able to articulate who would ever use it.

Technically, it was brilliant. But there was no business plan.

If they wanted to build a new kernel that could replace Linux on Android and/or Chrome OS, that would have been worth exploring - it would have had at least a chance at success.

But no, they wanted to build a new OS from scratch, including not just the kernel but the UI libraries and window manager too, all from scratch.

That's why the only platform they were able to target was Google's Home Hub - one of the few Google products that had a UI but wasn't a complete platform (no third-party apps, for example). And even there, I don't think they had a compelling story for why their OS was worth the added complexity.

It boggles my mind that Fuchsia is still going on. They should have killed it years ago. It's so depressing that they did across-the-board layoffs, including taking away resources from critically underfunded teams, while leaving projects like Fuchsia around wasting time and effort on a worthless endeavor. Instead they just kept reducing Fuchsia while still keeping it going. For what?

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cmrdporcupine ◴[30 Aug 25 00:55 UTC] No.45071001[source]▶
Not only did they target Home Hub, they basically forced a rewrite on it (us, I worked on the team). After we already launched. And made our existing workable software stack into legacy. And then they were late. Then late again. And late again. With no consequences.

100% agree with your points. To me watching I was like -- yeah, hell, yeah, working on an OS from scratch sounds awesome, those guys have an awesome job. Too bad they're making everyone else's job suck.

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raggi ◴[30 Aug 25 05:25 UTC] No.45072092[source]▶
By forced I guess you’re referring to the room full of leads who all said yes, but then reported otherwise back down to their ics to avoid retribution. I caught early wind of this from folks being super rude in early on the ground discussions and tried to raise it with Linus. One of the directors got his kickers in a twist and accused me of making a mountain out of a molehill. I guess clearly not, as the sentiment and division still stands.
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1. cmrdporcupine ◴[30 Aug 25 14:31 UTC] No.45074998[source]▶
I don't care who agreed to what, it's bad engineering practice to take a working successfully launched product and throw out its entire working software stack no matter how inelegant it seems. To what end? What did Fuchsia offer? When it finally shipped -- what, 2, 3 years late? --- custmers couldn't even tell it happened.

And in order to make it happen it also required writing the already-launched HTML-based UI in Flutter/Dart. Again ... why? What for? There wasn't even a working "native" Flutter at the time, despite promises, and there certainly wasn't a working accessibility stack -- no screen reader, no magnification, nothing -- so that all had to be kludged in. It was everything wrong with the "rewrites considered harmful" distilled.

Not to mention terrible for morale, execution, planning, budget, customer satisfaction.

I was just a lowly SWE 3 "IC" just in the trenches, not nearly as "important" as all that, so my opinion mattered not at all. But to me it violated every sound engineering / project planning principle I'd learned in the 15 years of my career up to that point. Just another event that led to me becoming quite cynical about the ability of leadership at Google to actually manage anything of significant complexity that wasn't ads/search related.

Again, Fuchsia .. very neat. But it didn't belong there.

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2. raggi ◴[30 Aug 25 17:28 UTC] No.45076424[source]▶
Customers not being able to tell that it happened was a goal of that deployment.

It wasn’t anywhere near that late the numbers you’re saying was about the whole build cycle - board bringup for one of the two boards first commit in zircon was 3y before launch (that codes public, I just checked and Mike landed it in 2018) - and discussions weren’t done then, that was before any prototype/demos could be done. There were sluggish stages and project management was rough, and there were delays at the end related to quality but the quality bar was necessarily high, particularly on the core system - don’t brick all the devices in the field. And we didn’t, and that’s actually a feat replacing everything from firmware to gui in the field without users noticing.

What was the goal? Well two things: fuchsia needed a first, and realistic shipping target that wasn’t excessively lofty. Nest needed to get out of the OS game so it could focus resources on product. Chris talked about this in his 9to5google interview.

It’s a shame you feel so sour about it, everyone involved did good work. I have friends from nest and some of the ics also have similar pained history from that time - it’s sad, once upon a time it was maddening. It’d have been so easy for a leader to substantially improve that. Sure plenty of things could have been better, for sure we could have fixed these awful sentiment and relationship issues (I tried, got burned for it - that even showed up in my calibration), but we all shipped.