[kmeisthax]

One thing to note is that RISC-V is only royalty-free for people making custom silicon implementations - i.e. the equivalent of an ARM architectural license. You still have to design the cores and that's the really hard part, moreso than designing the ISA.

Apple is in a unique position where they have all these Cortex cores for various reasons, but also have the resources to actually design a RISC-V implementation that could replace them all. I doubt the people designing flash controller ICs have that level of design experience.

[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.

[WatchDog]

There seem to be a bunch of open source risc-v cores. Such as the CORE-V cores. However I’m not sure how suitable they are for commercial use compared to the proprietary options.

[snvzz]

>You still have to design the cores and that's the really hard part, moreso than designing the ISA.

Designing them is an option. RISC-V's license allows doing so. But, unlike ARM, where your only alternative is to license ARM's own designs, in RISC-V there are several options.

You could use open source cores, or license cores from someone. As there's an open market of cores, there are several competing companies, offering several competing cores and support arrangements.

[phire]

The article is wrong, Apple don't really use ARM's Cortex cores within the M1

They already have a their own custom low-power arm64 core design for running these firmware tasks. They have about a dozen of them scattered around the M1, on top of the massive P and E cores.

There are still a few actual ARM inc designed cores spread around the motherboard, in various devices. But inside the SoC, most (if not all) are Apple's own design.

[dkjaudyeqooe]

The RV arch is much simpler than ARM and there are many more options in the market for licencing designs, besides the option of designing your own.

That's the real difference: RV is a real market with multiple vendors whereas ARM arch is more or less single vendor lock-in.