The ARM ISAs are not free to implement. ARM holds patents relevant to the ISA.
replyUntil the patents expire, which many have already.
replyThe aarch64 stuff still has some time, particularly if you want stuff like virtualization.
replyYou're vastly underestimating the amount of work that has gone into RISC-V that would need to be redone. It's not just a spec. There's an absolute mountain of software and hardware supporting it.
replySure. But … so was Linux, or Firefox, or GNOME or KDE, etc.
replyEven RISC-V itself was adopted by volunteers and supported by toolchains, and then kernels, and applications.
The amount of work is less a problem than the motivation. And motivation really just depends on recognizing that the status quo sucks, but is fixable.