[api]

How hard would it be to re-use a lot of the ALU, MMU, and other components from the Apple A line of ARM64 chips with a different decoder and pipeline? Pretty much all modern chips "emulate" their instruction set anyway with the real core being a proprietary uop machine.

[monocasa]

ALU - easy, it's pretty much orthogonal to ISA layout

MMU - they're pretty different

I def bet that if they're making an x86 chip, it shares a lot of RTL with their A series cores, but the distinction is probably more like they have a shared library of a lot of primitives, and have pretty different uarchs built from them.

[johntb86]

Would they do something crazy like x86-64 usermode and aarch64 kernel mode? You might be able to share more of the MMU and so on with that - though given the memory-ordering differences it would still be difficult.