10 billion RISC-V cores were shipped last year - mostly you wont see them because they're heavily embedded - in disk drives/etc - used to be every flash drive had an ARM core in it and paid a few pennies to ARM, that's likely to change quickly
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.
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.
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'
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.
And being blacklisted by ARM might hurt your business 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.
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.
That's the real difference: RV is a real market with multiple vendors whereas ARM arch is more or less single vendor lock-in.
They said "We estimate there are 10bn cores on the market already" (that would be since 2010). Then there's a slide that says "Nearly 80 billion RISC-V CPU cores by 2025".
https://www.eenewseurope.com/en/europe-steps-up-as-risc-v-sh...
that's from a talk at Embedded World in june 2022.
I can't find that talk on youtube. But there's another shorter talk that's online, from same CEO at the same conference, where they have a slide that says "North America. Industry adoption has taken off with millions of cores shipping from Nvidia, Western Digital, SiFive, and others."
...and USB flash drives are more likely to be based on 8051s than ARM in volume.
They don't need anything as powerful as ARM (and thus avoid the licensing fees), and it's a very price-sensitive market, so a fast 8051 + accelerator hardware is enough.
No doubt some of the more expensive ones may be ARM-based, but I think the 8051-based ones far outsell them in volume.
8051s are used in applications where a 4-bit MCU (yes, they do exist and are still in widespread use) is not quite enough, or they'd have chosen one of those instead.
A basic RV32 CPU is down to 500-700 LUT.
https://github.com/YosysHQ/picorv32
https://github.com/olofk/serv
https://github.com/MicroCoreLabs/Projects/tree/master/MCL51
(oh and 8051 are a pain to work with, they've taken far too much of my lifetime, they need the stake thru the heart thing)
An interesting observation is that RV32 has excellent code density. Meaning, in this sort of scenario, the ROM could be much smaller, or fit way more code at the same size.
That's still a huge difference, and as I mentioned above, the 8051 is found in applications which are very sensitive to cost. In terms of gate count, the lowest numbers I could find for a RISC-V core are in the 10-20k range, while an 8051 goes down to 2.7k:
https://www.electronicsweekly.com/news/design/eda-and-ip/805...
The company that owns MIPS, Imagination Technologies, has entirely dropped the MIPS ISA to instead focus in designing RISC-V cores.
Interesting in that Imagination have since announced RISC-V cores [2], but that's unrelated to any of the MIPS tech, and none of the MIPS engineers worked on it as the project started well after the sale.
[1] https://www.imaginationtech.com/news/completion-of-sale-of-m...
[2] https://www.imaginationtech.com/news/imagination-launches-ri...