[Taniwha]

There's lots of open source RISC-V cores - but can't be any fully OS ARM ones (even if someone's made a n OS ARM core you still have to pay ARM a royalty)

The big advantage to rolling your own private ISA is that there's already a rich compiler and O/S ecosystem for RISC-V while if you do use RISC-V it's all already there for you.

It really does feel like a second generation 'barn raising'

[Someone]

> but can't be any fully OS ARM ones (even if someone's made an OS ARM core you still have to pay ARM a royalty)

Wait long enough and you can. Even if you can’t work around them, patents expire, and you can copy the instruction set for reasons of compatibility.

Trademarks don’t automatically expire, though, so unless the trademark gets genericized (https://en.wikipedia.org/wiki/Generic_trademark) what you can’t do is call it an ARM CPU.

[londons_explore]

Arm will still blacklist you if you pull this trick.

And being blacklisted by ARM might hurt your business when you do actually need to buy something from them.

[snvzz]

>when you do actually need to buy something from them.

Protip: You don't.

Literally, just license whatever you need elsewhere. RISC-V has an open market of cores, with tens of companies and hundreds of offerings.