Re: Genuine question RISC-V / ARM
Apple wouldn't benefit at all from switching to RISC-V or creating its own ISA. The fees they pay to ARM for their architectural license are rather modest, it would take many years to recoup what it would cost them to go to a "free" ISA - probably many decades to recoup if they developed their own.
Even though they don't use ARM designed cores they still derive some benefit from using the ARM ISA for their own cores in terms of improvements made to LLVM (the base of their compiler) for ARM, and maybe someday from Windows/ARM if that ever becomes widely used and people want to run Windows/ARM in a VM to access certain applications not native on macOS.
Plus they still have flexibility in adding their own non-standard instructions if they want, their only real limitation is that their ARM chips must be able to pass ARM's certification tests so they can't change the meaning of existing ARM instructions. Once they were able to drop support for AArch32 and go 64 bit only they shed any legacy debt so have a pretty clean ISA that doesn't require supporting stuff they don't use or care about in 2022 like x86 designs must. That may be a minimal cost for Intel and AMD since those older 16 bit modes etc. don't change, but it isn't zero.
Biting the hand that feeds IT
