I'm not sure Apple would want users to run anything but Apple operating systems on their hardware, and the other way around (fighting against hackintoshes back in the day).
I hope to be proven wrong though, as their hardware is really interesting.
They've never taken issue with other OSes running on their hardware. They made Boot Camp for Intel Mac users to run Windows and wrote Windows drivers to use Apple-specific hardware like the iSight cameras. They even showcased this feature in the TV ads. Linux also worked but wasn't explicitly supported.
> They've never taken issue with other OSes running on their hardware.
What on earth are you talking about, iPads, iPhones and all other new devices from Apple outright lockout any kind of 3rd party OS from booting on them.
MacBooks are the only ones grandfathered into old behaviour of actually allowing 3rd party OSes (although they've also lost the ability to boot Windows in latest generation as well).
It's clear the context of the whole thread is Apple's OS X/macOS based lineage of machines. Also, they haven't lost the ability to boot Windows, seemingly due to licensing issues with Qualcomm, Microsoft hasn't offered a Windows port yet. Of course, one couldn't boot directly into Windows from the previous generation of PowerPC based Macs either...
"They've never taken issue with other OSes running on their hardware." is a false statement even within context of this thread. They've thanken issue with other OSes on their hardware.
Is it any different to the false statement that is "(although they've also lost the ability to boot Windows in latest generation as well)"? The last line specifically refers to macOS. No need to be deliberately obtuse.
Apple doesn't really care about individual hackintoshers. Some of their devs have griped about the uselessness of stack traces and logs coming in from hackintoshed machines (bogus errors produced by slight hardware mismatches, drivers developed by amateur community members filling logs with garbage, etc) but they've never gone after anybody who was hackintoshing for personal use. There's even been fairly big YouTubers who've done it without issue, and back when Macs were Intel only and had abysmal thermals/performance a surprising number of Mac/iOS devs were using hackintoshes as their primary dev machines that they submitted to the App Store with.
Where they draw the line is selling hackintoshed machines or any of the tools to facilitate the process. Eliminate financial gain from the equation and you'll probably be fine.
Hector Martin claims so which (frankly) suggests he has some insiders.
However, just because Apple "runs linux" doesn't mean they "run linux" the way you are thinking. It's very easy for corporations to write slapdash, horrific, unmaintainable kernel forks that run on a specific piece of hardware. That's just fine when you are testing hardware before handing it to your OS team, but absolutely unacceptable for upstreaming.
For examples of this, take a look at old Android devices (and their ancient kernels), or the original Correlium port of Linux to Apple Silicon (which happened almost half a year before the Asahi Linux beta - but the code was sheer unmaintainable crap). Upstream it? Heck no - it would be rejected entirely and need almost a total rewrite from scratch. Just because you can write a functional driver doesn't mean it is anywhere close to a good, maintainable driver.
So, in a nutshell... yes, Apple does use Linux for early manufacturing tests. But it would almost certainly not be in a state where we could benefit much from it, and certain features would likely not be implemented. It's not anywhere near as simple as "Apple has done the work already - just upstream it please!"
> Hector Martin claims so which (frankly) suggests he has some insiders.
Eh, I've heard the same thing form people I trust, and I'm not the Apple news version of deep throat or something. It's simply not a very well kept secret.
Although part of me wonders if the code will flow the other way. Now that marcan has put in the elbow grease to upstream concepts like 16KB pages, the non standard ordering for regular MMIO and PCI on Apple Silicon, etc, will Apple embrace those in their custom distro to avoid having so much un-upstreamed code? We'll probably never find out, but it's fun to think about.
To what upstream project?