[yjftsjthsd-h]

It's possible that OpenPOWER has no advantages today, but I remain curious how we got here; my understanding is that POWER and SPARC both had open source versions before RISC-V was created, so why didn't those get picked up but RISC-V did?

[ilc]

SPARC is a neat ISA, but the concept at the core: register windows, did not take off.

OpenPOWER: It may have to do with the size of the ISA when it started to be open.

RISC-V, when announced was a small ISA. That means making chips is easier.

It could just be the new hawtness effect. Look at how many people use NoSQL when SQL would work just fine ;).

[brucehoult]

> RISC-V, when announced was a small ISA

It still is today, comparatively.

RV32I/RV64I are very very small ISAs. RV64G is pretty small -- comparable to, say, MC68010, and a lot simpler than i386.

These small subsets will be supported by the ecosystem forever, for those who want to use them. They will also remain, unchanged, at the heart of more complex standards such as RVA23 and successors, and make up most of the instructions in programs.

[Findecanor]

RISC-V's success has been mostly in small embedded systems — where a POWER chip would be overkill or unsuitable. The core ISA is very small, thus cheap, and then extensible. The design even encourages proprietary extensions. Then it has grown from there as ISA extensions have been ratified.