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

tbh linux has quite a bit of cruft in it these days at the syscall and interface layer.

if youre apple, it does make sense to do stuff from scratch. i think in a way, software guys wind up building their own prisons. an api is created to solve problem X given world Y, but world Y+1 has a different set of problems - problems that may no longer be adequately addressed given the api invented for X.

people talk about "rewrite everything in rust" - I say, why stop there? lets go down to the metal. make every byte, every instruction, every syscall a commodity. imagine if we could go all the way back to bare metal programming, simply by virtue of the LLM auto-coding the bootloader, scheduler, process manager, all in-situ.

the software world is full of circularities like that. we went from Mainframe -> local -> mainframe, why not baremetal -> hosted -> baremetal?

You can still do “unsafe” stuff in rust, and people do. It’s perfectly possible to write safe C and C++ these days. And you don’t have to deal with a borrow checker, and a very small pool of developers available to hire.

> It’s perfectly possible to write safe C and C++ these days.

It's also very hard to do so.

oh, i didnt mean to invoke rust in any technical sense - i brought up rust to introduce an example of the attitude that rust people are known for, namely "why not rewrite everything?", which a lot of people have a kneejerk rejection of.

Apple doesn't do a lot of baremetal development from scratch that I'm aware of. The Lightning to HDMI dongle bootstraps an XNU kernel with an AirPlay decoder into 256MB RAM, for instance.

Doesn't Apple pretty much own their whole stack? You mentioned XNU, which they made...

Their CPU, their boards, their firmware (presumably), their OS[1], much of the perhipherals are theirs, too.

Lots of companies try to emulate Apple, but it's very hard to pull off.

[1] Yes, they use some parts from Mach and FreeBSD in their OS, but the amalgamation is theirs, and they support and change the whole thing as needed.

The chrome team doesn't manage that, but perhaps they are just bad at C++ /s

Boot loader firmware, initially done in a Safe C dialect, nowadays one of the reasons Embedded Swift came to be.