[gchadwick]

ISAs are complex things so you can't say one is technically superior to the other.

I would say you're right though in that RISCV enjoys the success it's seeing due to the open specification and licensing model. People generally aren't drawn to RISCV because of technical innovation.

[brucehoult]

The base specification (IMAFDC) has little to no innovation, simply avoiding the mistakes of the past. We've got 60 years of experience with RISC-style instruction sets, so that's about consolidation not innovation.

However RISC-V is an excellent base upon which to innovate. You can see that in things such as the Vector extension, the memory model developed by industry and academic experts world-wide, and CHERI fine-grained memory-protection.

[fanf2]

CHERI was originally based on MIPS, then ported to ARM and later RISC-V.

[brucehoult]

The place you can get a real physical commercially available CHERI implementation is RISC-V:

https://codasip.com/press-release/2023/10/31/codasip-deliver...

That's largely because if you base a product on Arm or MIPS you have the choice of getting them to actively invest in and support you, or getting sued into oblivion by them.

THAT is why RISC-V is the most friendly ISA to innovation and where most future innovation will happen. Because innovation comes not only from internally inside Intel or Arm or MIPS (who have switched to RISC-V now anyway) but from a myriad of possible sources.

[rwmj]

The base RISC-V tends to avoid innovation, because we've been burned in the past (register windows, branch delay slots etc)