[Taniwha]

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

[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.

[kats]

Ok I looked into this some more.

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."

[userbinator]

It's more likely that RISC-V replaces MIPS than ARM, although it's certainly competing for the latter too.

...and USB flash drives are more likely to be based on 8051s than ARM in volume.

[snvzz]

RISC-V replacing MIPS is old news. It is a done deal.

The company that owns MIPS, Imagination Technologies, has entirely dropped the MIPS ISA to instead focus in designing RISC-V cores.

[kimixa]

Imagination Technologies sold off MIPS in 2017 [1] - while RISC-V might have been a thing back then, it was certainly nowhere as known as it is today, and well before any decision to focus on RISC-V.

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...

[snvzz]

Missed the sale. Now both MIPS[0] and Imagination are instead doing RISC-V.

0. https://www.theregister.com/2022/05/11/mips_riscv_chips/

[arcticbull]

I'm pretty sure they're all ARM. Why would they be 8051s? Are there any sufficiently performant 8051 cores?

[userbinator]

Here's one with a 250MHz 8051: https://github.com/flowswitch/phison/wiki/PS2303

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.

[sitkack]

RV32 will turn out to be the 8051 of the present. The 8051 was the Doge Dart of embedded automation. I bought a book in Vietnamese in Vietnam in 2005 on embedded development hardware and software for the 8051. If the diagrams were any indication of the quality, the writing was excellent.

[userbinator]

I highly doubt it. As "reduced" as RISC-V is, 8051 is still tiny in comparison.

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.

[jpfr]

There's a community doing "fpga golf". That is, reducing the number of LUT required to implement a CPU of a given ISA.

A basic RV32 CPU is down to 500-700 LUT.

    https://github.com/YosysHQ/picorv32
    https://github.com/olofk/serv

A minimal 8051 requires about 300 LUT.

    https://github.com/MicroCoreLabs/Projects/tree/master/MCL51

Not sure how this translates from an FPGA to a transistor count. But RV32 and 8051 should be within a factor of 2-3.

[mhh__]

Shipped last year or shipped in total?

[xiphias2]

Last year 3B, and the total cores shipped got over 10B recently. I couldn't find more data though.