Apple to Move a Part of Its Embedded Cores to RISC-V

https://www.techpowerup.com/298936/report-apple-to-move-a-part-of-its-embedded-cores-to-risc-v-stepping-away-from-arm-isa

by gcoguiec • 4 years ago

118 48 4 years ago

techpowerup.com

Taniwha3• 4 years ago

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• 4 years ago

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.

WatchDog• 4 years ago

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.

snvzz8• 4 years ago

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.

Taniwha3• 4 years ago

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'

phire• 4 years ago

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• 4 years ago

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.

userbinator4• 4 years ago

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.

arcticbull• 4 years ago

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

snvzz8• 4 years ago

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.

mhh__• 4 years ago

Shipped last year or shipped in total?

xiphias2• 4 years ago

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

kats• 4 years ago

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."

kevmoo1• 4 years ago

I wish I could buy stock in RISC-V (in the abstract).

snvzz8• 4 years ago

If there was a RISC-V ETF, internally using companies that sell RISC-V IP and hardware, I'd definitely buy it, and prefer it over NASDAQ (QQQ).

rwmj2• 4 years ago

Could you join VC funds which are investing in Rivos/Ventana/SiFive/etc? (Genuine question - I have no idea if this is possible or not)

A lot of the RISC-V action is going on in China which is obviously rather more difficult. Over there much of that is funded by the Chinese state.

snvzz8• 4 years ago

Testing the waters.

Notably, Apple was among main investors when ARM was a startup; they're not doing this to save in ARM fees.

systemvoltage• 4 years ago

Jim Keller's slide [1] on RISC-V. Simple words. Grug like.

[1] https://www.techgoing.com/jim-keller-innovation-is-happening...

beebeepka2• 4 years ago

I wish I could invest in his company. He's obviously biased towards RISC-V but things are certainly going this way.

Jtsummers• 4 years ago

This is a two paragraph, highly speculative "summary" of [0] which was posted earlier [1].

But even reading the original article, it barely mentions Apple and CharlesW highly editorialized that submissions title:

The Apple bit:

For example, Apple’s A15 has more than a dozen Arm-based CPU cores distributed across the die for various non-user-facing functions. SemiAnalysis can confirm that these cores are actively being converted to RISC-V in future generations of hardware.

The original title:

SiFive Powers Google TPU, NASA, Tenstorrent, Renesas, Microchip, And More

The bulk of the article is about Google and hyping Risk-V, not Apple.

[0] https://semianalysis.substack.com/p/sifive-powers-google-tpu...

[1] https://news.ycombinator.com/item?id=32872927

Melatonic• 4 years ago

Bit of a RISC-Y manoeuvrer no?

*Badumph*

SanjayMehta• 4 years ago

They had a job posting a few months ago which asked for RISC-V experience.

edit: they still have them.

https://jobs.apple.com/en-us/details/200349341/system-archit...

tiffanyh• 4 years ago

What benefits does RISC-V have over ARM besides it being open/free?

teitoklien• 4 years ago

What benefits does Linux/BSD have over Windows, as a highly productive development environment outside of all the possibilities it had opened by being open/free ?

wyldfire• 4 years ago

IMO the comparison is similar but it's just not quite the same thing.

Don't get me wrong - it's a big deal to have this popular open ISA. But I just don't think it's anywhere near as big a deal as Linux is/was.

sitkack3• 4 years ago

smaller instruction set, Arm has grown, reference manual is over 6k pages

smaller easier to read specs

easier to get new features ratified, org is a steward, isn't seeking rents

easy to add custom instructions

lots of OSH implementations to choose from

large 3rd party ecosystem, IP, compilers, OS, etc.

cestith2• 4 years ago

To be fair, even with a closed ecosystem for the cores themselves there is a large third party ecosystem in compilers, OSes, support hardware, and documentation around ARM these days. It's interesting how quickly all of that popped up around RISC-V the past few years though. ARM has had decades getting where they are with the ecosystem around their cores.

rrss• 4 years ago

Smaller instruction set and shorter reference manual aren’t necessarily good attributes. The risc-v reference manual is short because in part because it is has terse-to-vague descriptions of things (not great for a specification) and because the ARM ARM specifies a bunch of things which are omitted from the RISC-V architecture spec, which either implementors will have to design themselves or the RISC-V org will eventually add in a revision or extension spec (e.g. Zicbom, Zicboz, Zicbop)

rwmj2• 4 years ago

It's completely permissionless. Grab an open source core, tweak it how you like, and move into production. No one will ask you to sign a licensing agreement or pay any license fees.

Depending on what you're doing this may or may not be an advantage, but it's certainly a large difference from Arm. It could lead to innovation happening more quickly since there's no need to wait for a gatekeeper, it's unclear at the moment how much that matters.

snvzz8• 4 years ago

Take a look at e.g. SiFive's core IP offerings.

Given any ARM core (save the wildly inefficient, but faster top performance cores like the X1/X2), SiFive's got one that's like below a third of the size, uses dramatically less power and runs somewhat faster.

This is enabled by the quality of RISC-V's architecture.

The base spec has less than 50 instructions. Even with everything and the kitchensink in there (which is possible; as of the batch of extensions approved in late 2021, RISC-V is not lacking any major features ARMv9 or AMD64 have), RISC-V is still a few hundred instructions, rather than thousands.

And, despite having highly competitive 32bit code density (might be the best by year end, considering with current state of non-finished Zc/B extensions it already is) and the highest code density of 64bit architectures (by comfortable margin), RISC-V is very easy to decode. The compressed code extension does barely even complicate decode, and is still either 2x 16bit instructions or a 32bit one.

In practice, this means cores can be tiny relative to equivalent ARM cores, and SiFive's portfolio is a good demonstration of that.

By contrast:

- AMD64 aka x86 has 1-16 byte instruction length which means a 2-decode or wider implementation has to bruteforce every possible instruction start and discard the bad results. This makes complexity scale exponentially with decode width, and Intel and AMD have found that 4-decode is a practical limit.

- ARMv9's aarch64 is fixed 32bit (yet only slightly easier to decode because of that, relative to thumb2 and RISC-V). This enabled Apple to go 8-decode with the M1. But this comes at the expense of code density: If you want to implement a high performance core, you're going to need a huge L1, which besides huge area and power penalty, is also going to cap the clock the cache can achieve. Regardless, the situation is much better than AMD64(x86), and has enabled Apple to go 8-decode on the M1.

And this is why I think Apple moving to RISC-V in supporting cores is only the first step, and the main cores will eventually follow.

dagmx• 4 years ago

This is based on Dylan Patel’s speculation, and he quite commonly just comes up with something that he wants to be reality and presents it as fact.

ddingus• 4 years ago

Apple end game:

Apple ISA. Might take them a decade, but in the end, they will eventually do all their own thing.

thebitstick• 4 years ago

riscv64gc-apple-darwin

Apple to Move a Part of Its Embedded Cores to RISC-V

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