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I know, because Apple went through the trouble of close-sourcing the M1 bring-up code in XNU source dumps... because it suddenly contains secret new instruction

I know, because Apple went through the trouble of close-sourcing the M1 bring-up code in XNU source dumps... because it suddenly contains secret new instructions, while until now ARM XNU builds were largely public. These instructions enable an entire new set of parallel execution modes, among other things, to run more protected kernel code. Completely nonstandard stuff. Also, Apple somehow managed to push custom kernel support to the documentation of kmutil, but not the actual binary, until several macOS releases later. That would only happen if the latter got pulled for some extraneous reason. I've been working on this since December; the entire situation is all showing signs pointing straight at ARM's lawyers having gotten involved to some extent.

monocasa 6y ago
The kmutil stuff sounds way more like they cut it at the last second for some QA issue, but the documentation tech writers are a different team and that part was missed. They wouldn't have figured out issues with lawyers this quickly. The bring up stuff could be explained by being scared about some patent nonsense.
skissane 6y ago
I think there is another explanation for this than "they are breaking ARM's rules and either trying to hide it or getting in trouble" It is: "They are following ARM's special rules for Apple only but they aren't allowed to tell anyone that those special rules for Apple only exist" They might decide to leave certain processor extensions undocumented, even close source code which uses them, because they are worried disclosing them would implicitly reveal the existence of the "special rules for Apple", possibly violating the confidentiality clauses of the ARM-Apple contract containing those special rules. So I still don't see how you know that "There is no such 'do wtf you want' license", when the behaviour you describe is compatible with their being one, but its existence being secret
- marcan_42 6y ago
  That's what I said: that they got a special exemption (which is not part of ARM's official license offering) to allow them to do this for embedded use cases (iOS devices), which implied that they wouldn't be documenting or having other people use these instructions. The problem is that the M1 threw a wrench in the works because now suddenly running non-Apple code that can use these instructions is allowed, and everyone else can see that they exist, so suddenly the existence of that special exemption is public.
  - skissane 6y ago
    > that they got a special exemption (which is not part of ARM's official license offering I agree except I'd say that it is part of ARM's official license offering, but only if your name is "Apple".

monocasa 6y ago

The kmutil stuff sounds way more like they cut it at the last second for some QA issue, but the documentation tech writers are a different team and that part was missed. They wouldn't have figured out issues with lawyers this quickly. The bring up stuff could be explained by being scared about some patent nonsense.

skissane 6y ago

I think there is another explanation for this than "they are breaking ARM's rules and either trying to hide it or getting in trouble" It is: "They are following ARM's special rules for Apple only but they aren't allowed to tell anyone that those special rules for Apple only exist" They might decide to leave certain processor extensions undocumented, even close source code which uses them, because they are worried disclosing them would implicitly reveal the existence of the "special rules for Apple", possibly violating the confidentiality clauses of the ARM-Apple contract containing those special rules. So I still don't see how you know that "There is no such 'do wtf you want' license", when the behaviour you describe is compatible with their being one, but its existence being secret

marcan_42 6y ago
That's what I said: that they got a special exemption (which is not part of ARM's official license offering) to allow them to do this for embedded use cases (iOS devices), which implied that they wouldn't be documenting or having other people use these instructions. The problem is that the M1 threw a wrench in the works because now suddenly running non-Apple code that can use these instructions is allowed, and everyone else can see that they exist, so suddenly the existence of that special exemption is public.
- skissane 6y ago
  > that they got a special exemption (which is not part of ARM's official license offering I agree except I'd say that it is part of ARM's official license offering, but only if your name is "Apple".