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

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521 points OlympicMarmoto | 1 comments | 29 Aug 25 16:45 UTC | HN request time: 0.21s | 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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dist1ll ◴[29 Aug 25 22:57 UTC] No.45070345[source]▶
Intel still does it. As far as I can see they're the only player in town that provide open, detailed documentation for their high-speed NICs [0]. You can actually write a driver for their 100Gb cards from scratch using their datasheet. Most other vendors would either (1) ignore you, (2) make you sign an NDA or (3) refer you to their poorly documented Linux/BSD driver.

Not sure what the situation is for other hardware like NVMe SSDs.

[0] 2750 page datasheet for the e810 Ethernet controller https://www.intel.com/content/www/us/en/content-details/6138...

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throwaway2037 ◴[30 Aug 25 05:53 UTC] No.45072199[source]▶
Wow... that PDF is 2,750 pages! There must be an army of technical writers behind it. That is an incredible technical achievement.

Real question: Why do you think Intel does this? Does it guarantee a very strong foothold into data center NICs? I am sure competitors would argue two different angles: (1) this PDF shares too much info; some should be hidden behind an NDA, (2) it's too hard to write (and maintain) this PDF.

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jovial_cavalier ◴[30 Aug 25 14:54 UTC] No.45075185[source]▶
Look up the Texas Instruments am3358. It's a tiny SOC, it was used in the beaglebone black. Its technical reference manual[1] is over 5000 pages, and it details all peripherals, all of the interconnects and every single register in the system. This, by contrast, is really just an overview.

Regards to (1), if you don't publish this information you're not selling a CPU, you're selling a very expensive chunk of sand. There is simply no way that a customer can guess at what your implementation looks like. Additionally, Intel barely has IP in the traditional sense. They hold patents, but their only real competitor in making x86 processors, AMD, has a long-standing mutual non-enforcement agreement wrt patents.

Regards to (2), I'm guessing a majority of this PDF can be generated sort of like you generate API documentation from doxygen comments.

[1]: https://www.ti.com/lit/ug/spruh73q/spruh73q.pdf?ts=175651560...

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1. GeorgeTirebiter ◴[30 Aug 25 20:01 UTC] No.45077557[source]▶
I worked on a similar TI SoC -- with War-and-Peace-sized datasheet. My eyes burned out and brain exploded. Ultimately, another engineer had to take over the project -- or rather TEAM of engineers, of which I did only a part. It's simply to much complexity to expect one engineer to grok it all, do the schematic & PCB & power supply & hi-speed MIPI connections and radios and... and THEN to write the software for it all. It's too much. (This is the Life one gets in Startups, it seems -- worked to the (beagle)bone!)