There's a rumor that they have an internal Linux distro that the silicon validation team at Apple uses on their hardware so that they don't have dependencies on the software division.

I recall reading that was only for bringup though, not full peripheral support?

Either way, that's a good point and does have clear internal utility. It's certainly easier to get Linux running on a new chip than OSX!

> It's certainly easier to get Linux running on a new chip than OSX!

I'd say that's wrong. From the outside view, perhaps, but an internal Apple team can certainly get macOS to sing and dance on whatever they need very quickly.

Good point. The x86 OSX port was created and initially maintained by a single person, if the folklore is accurate.

A similar effort for Linux would usually benefit from related work by many people. For OSX or macOS it would need to be an explicit project, starting with fewer initial bits. But the internal Apple team would be exactly the right experts for the job, so it would be easier to organize at least.

What operating system(s) do they use to run their cloud services? Given that MacOS has moved in a different direction for many years, it seems a bit unlikely that they run that at this point.

I think it's all Linux these days.