This is cool!

At the same time, not being part of the Apple ecosystem, should I be worried about the closed nature of this. I have been using Linux for over two decades now, and Intel seems to be falling behind.

(I do realize Linux runs on the M1. But it's a mostly hobby projects, the GPU is not well supported, and the M1/M2 will never(?) be available with open H/W.)

Apple isn't going to somehow make 64 bit ARM in to something proprietary. Sure, they have their own special instructions for stuff like high performance x86 emulation, but aarch64 on Apple is only going to mean more stuff is optimized for ARM, which is good not only for Linux, but for other open source OSes like the BSDs.
There are no special instructions for x86 emulation.
There's a whole special CPU/memory mode for it, actually.

https://twitter.com/ErrataRob/status/1331735383193903104

I don't really need Rob to explain to me how Apple's processors do TSO ;) There are no special instructions for Rosetta regardless.
>I don't really need Rob to explain to me how Apple's processors do TSO ;)

Lemme just look up TSO and...

https://github.com/saagarjha/TSOEnabler

...Oh. Fair enough, my mistake :P

Is there not an instruction to switch into TSO mode, though? Wouldn't that technically count? :P