> where as if you go RISC-V, you are free to switch CPU providers.

Idk, this really isn't as true as you'd think. Yes RISC-V is an open and free ISA which will cut out some fees, but you'd still have to license IP/chip designs (if you can't make your own) and they could only undercut ARM by a little bit. Further, the lack of mobility across chips/boards/whatever is not usually from the ISA, but from the BSP, SDK, etc. so you still would have substantial lockin unless we somehow standardize on that (lol)

ARM actually has a pretty good story for how they can undercut RISC-V prices in that they can design the ISA rather than accepting the decisions of a committee. That committee used to make good choices, but things like the vector ISA seem more suspect.

The general consensus I've heard is the vector extension is good? I do agree the design by committee is less than ideal, but the ability to add vendor extensions at all is nice for certain markets.

The vector ISA seems alright to me. Particularly compared to Neon, but even compared to SVE.

Part of the issue here is that nobody is going to build something free on top of someone else's property. What good is a "free" design if you still have to pay ARM?

Whereas once you have a free ISA which is actually in widespread use, you could get some designs out of universities or major corporations which intend to use them rather than sell them as their primary business and then release the design for the same reason they do for Linux code, potentially under a copyleft-style license.

Those designs aren't going to be competitive with the state of the art, at least in the beginning, but they don't have to be. All they have to be is low power enough to stick in an embedded device and fast enough to run the display on a refrigerator and the lack of a license fee would cause them to replace a zillion ARM chips that currently go into every IoS device and <$200 phone and consumer internet router. That's a huge chunk of ARM's market.

Then someone like Amazon evaluates this thing for something like the Kindle and finds that it's almost good enough, all they have to do is throw a couple of engineers at it for a short period of time, so they do and it gets released because what do they care of some non-competitor uses it in some cheap laptop. Commoditize your complement -- now laptops are cheaper and people buy more laptops on Amazon.

Meanwhile the "small project" uncompetitive boards start to have their own open source BSP and SDK under the BSD license, which means anybody else can fork it for their own thing, and that's a competitive advantage so it happens a lot. But now it's way easier to reverse engineer the code because 95% of it is unmodified, so you start getting community replacements for that stuff and with any luck the OEMs stop even producing it and point you to the open source repository.

It could be a long time before that takes over the high end, if that ever happens, but the low end? It's almost inevitable. And the high end is AMD64 and Apple, the latter of which has all the leverage in the world over ARM because they could always switch to RISC-V.

As a layperson though, how would I be able to tell whether any of this is true? When I have to target platforms as a software developer, the truth is, I’ll do whatever Microsoft and Apple tell me to. By the time Apple is shipping a RISC-V phone I hope to be retired!

For any kind of high-level code, "platform" is something like win32 or Android or Qt. The underlying hardware architecture is the compiler/interpreter's problem.

The people dealing with assembly know who they are, but much of that is the sort of work that cares a lot about shaving off a few cents worth of license fee for an embedded device.

Until it becomes the users problem (e.g. PowerPC -> Intel -> ARM transitions)

For users of general purpose computers this is caused almost entirely by closed-source software. Most of the architecture-specific code is part of the operating system, and by the time you're doing an architecture transition the OS itself runs on the new architecture. The third party applications largely aren't dependent on a specific architecture but they're compiled for one.

With open source you could just recompile for the new architecture. Linux has always run on just about every one under the sun and the user largely can't even tell the difference. But if you don't have the source code you can't do that.

Closed-source systems could avoid this by compiling to bytecode, which is essentially what Android does, so transitioning to RISC-V would be much less trouble there than it would be for e.g. Windows.

> As a layperson though, how would I be able to tell whether any of this is true?

You probably won't ever know. Do you know the architecture of the microcontroller on your first computer's hard drive? I don't.

The stuff that RISC-V will replace first is the low-margin hardware that can be mass-produced by China et. al and exported without license violation. ARM's goose was already cooked in this sense, and even ARM China won't fix it. For IO controllers, ICs and network switches, it's hard to see why manufacturers would stick with higher-margin ARM hardware. If RISC-V cores are cheap, stable and available, you could replace them without the user ever noticing.

> By the time Apple is shipping a RISC-V phone I hope to be retired!

Apple is reportedly looking to replace some of their A-series ICs with RISC-V ones: https://www.techpowerup.com/298936/report-apple-to-move-a-pa...

Hopefully you don't intend to retire this soon :p

Apple holds a rare Architecture license to the ARM ISA due to their role as a founding partner, and can make original implementations without incurring licensing dues, as they do with the A and M series CPUs. I understand why they would want to switch to homegrown designs instead of licensing ARM reference designs (which they do have to pay for), but why migrate instruction sets too when RISC-V doesn't save them any marginal cost over novel ARM designs that would be binary compatible with the existing firmware?

> Apple holds a rare Architecture license to the ARM ISA due to their role as a founding partner, and can make original implementations without incurring licensing dues

Sorry, the architecture license wasn’t a thing when Arm was founded and there is no way that Arm would hand out free licenses at a later date. It’s just a myth.

"We have entered into a new long-term agreement with Apple that extends beyond 2040, continuing our longstanding relationship of collaboration with Apple and Apple's access to the Arm architecture," - ARM's IPO Document.

I assume they paid something for it, but who knows how much, ARM and Apple have not decided to tell us.

Source: https://www.sec.gov/Archives/edgar/data/1973239/000119312523...

Western Digital announced an open source core ("SweRV") in 2019, so I assume they already use them now that we are a few years on from that announcement.

https://github.com/westerndigitalcorporation/swerv_eh1

https://news.ycombinator.com/item?id=25002448

Honestly, this is conjecture at best, there have been other open ISAs that didn't manage to capture the market like this. That isn't to say I don't think RISC-V will capture a lot of market share, but I'm not going to make specific predictions about how much and where.

Of course it's conjecture. If you know anyone who can reliably predict the future I'd like to meet them.

But previous open ISAs were in the wrong market segment. Okay, SPARC is open, but it's also Oracle and no one trusts them, and the existing SPARC ecosystem is the enterprise market which expects big, hot hundred-thread systems and has no use for a simple dual-core CPU at 800 milliwatts. But that's the thing you can produce with a low budget, so it never goes anywhere or no one even makes one.

People are starting to use RISC-V for the thing where that actually works.

MIPS? PowerPC?

They're all open, albeit with somewhat varying definitions of the term.

MIPS wasn't opened up until they were already dead, and then almost immediately threw in the towel and joined up with RISC-V.

PowerPC basically the same, not opened until after it was irrelevant. OpenPOWER is in the same enterprise market as SPARC and IBM is not far from Oracle on the "do not engage litigious bureaucracy" chart.

MIPS didn't really open. They made a big deal about it, but it turned out to mean something to the effect of 'we'll open more of our build system to partners who pay for a traditional MIPS license. No third party MIPS cores. No general release of MIPS RTL.'

> Whereas once you have a free ISA which is actually in widespread use, you could get some designs out of universities or major corporations which intend to use them rather than sell them as their primary business and then release the design for the same reason they do for Linux code, potentially under a copyleft-style license.

We've had open ISAs for decades. The problem isn't with ISA licensing, the problem is cost-of-entry.

Most people have a computer...it costs nothing to install Linux and GCC/rustc/Python/etc and start contributing to open source software. For open hardware, you need (at minimum) a decent FPGA for testing/development; but access to fabrication resources to be in anyway competitive.

Don't get me wrong, I'm generally pro on RISC-V; I just don't think it's the revolution everyone is making it out to be.

> Most people have a computer...it costs nothing to install Linux and GCC/rustc/Python/etc and start contributing to open source software. For open hardware, you need (at minimum) a decent FPGA for testing/development;

That wasn't even true when open source got started. Typical access was to expensive mainframes and VAXen available only in universities and major corporations. PCs were only starting to become a thing and most people didn't have one.

That model still works if you need something expensive. Get your university to buy one, or your company if it will save them $0.05/unit on the ten million devices they sell. Or you rent one in the cloud.

You also might not need your own. A project gets started by someone who does have access to a decent FPGA, you want to contribute to it, great. They give you remote access to the FPGA.

Meanwhile FPGA prices keep going down.

> but access to fabrication resources to be in anyway competitive.

Which is available to anyone, if you have customer demand. They've made millions of Raspberry Pis.

> That wasn't even true when open source got started.

Which is why it took off when computers became accessible; and continued growing with even further ubiquity.

> You also might not need your own. A project gets started by someone who does have access to a decent FPGA, you want to contribute to it, great. They give you remote access to the FPGA.

Cool, so we're back to bottlenecked accessibility.

> Which is available to anyone, if you have customer demand.

Not hobbyists. To reiterate, open hardware (including ISAs) is as old as open software.

You're delusional if you think either are anywhere equivalent.

> Which is why it took off when computers became accessible; and continued growing with even further ubiquity.

So things like FPGA prices going down over time or being available to hobbyists via cloud providers.

> Cool, so we're back to bottlenecked accessibility.

Anyone with a computer and an internet connection can contribute, all they have to do is send an email to the project maintainer. It's obviously not as good as everybody already having the hardware, but it could be good enough to actually make it happen.

> Not hobbyists.

The model would be that there is a public repository with a design in it, anyone can contribute, and then every year or two they do a freeze and a production run which anyone can buy including the hobbyists who made contributions.

It feels like your argument is that Debian can't exist because a hobbyist doesn't have the resources to build a whole operating system. One doesn't, but a million of them do, especially if they can start with a basic design released by a major corporation or university or government.

You're not wrong, but having two choices of supply does wonders for squeezing profit margins from both back to the customer. Duopolies are terrible but better than monopolies.

Softbank has spent 7 years and a CEO finding out how difficult just raising prices is.

Especially when your lifeline is tied to Apple. No way are they going to manage to raise prices in a meaningful way.

Apple was one of the founding investors of ARM back in 1990 - it's likely they have an extremely generous licence and pricing terms as a result.

Apple’s involvement with ARM’s founding has zero impact on their negotiations or pricing.

It does when that involvement means they're one of the few architecture licensees. Allegedly.

They have an architectural license (for Arm v8/9) because they are a huge customer with deep pockets not because of a shareholding they sold a decade before that architecture was announced!

It's not the deep pockets per se, but the hand Apple had in designing AArch64. Apparently their relationship with ARM is more like the Intel/AMD relationship, ie. cross-licensing.

SoftBank has/invests so many business related to Apple (like mobile career), that may affected to negotiation.

> No way are they going to negotiate to raise prices in a meaningful way against their largest client.

Why not? It's not like Apple will have anywhere else to go for the next 8 years. x86 cores are too slow and power-hungry for the foreseeable future, and building their own risc-V core will take... at least 8 years.

8 years sounds like an absurdly long time to retrofit a different instruction set onto an existing CPU core design.

The deal with apple is probably 0.1% of revenue from all hardware sales that contain ARM IP or something similar.

Which means that if Apple decide to switch to RISC-V to save money, the deal is still in effect, but no money will be paid, so there might as well be no deal.

You think it's that low?

Yes. For ARM, having apple as a customer is a massive investor and customer confidence boost.

For Apple, they won't offer much because they could develop their own CPU architecture ISA pretty easily (they control all code and compilers for the platform after all, and already employ lots of compiler and CPU developers).

Building out tooling and even chips based on RISC-V is handing the future to China. They’re going all in because it’s an ISA that the west generated and builds support for but is free to use, which plays into their strengths of lowest cost and their ambition to own the future chips of the world.

You are right that China is going on in on RISC-V in part because of Western sanctions. It is yet another reason why RISC-V has so much momentum. It is in China's interest to destroy Intel's and ARM's competitive advantages and it is pouring money and people into it.

They wouldn’t be producing ARM or x86 even if no sanctions. They want to own an entire ecosystem.

An architecture that's developed in public that anyone can implement is a funny way to achieve that. Particularly given that western firms do largely follow the IP rules, if China wanted an ecosystem they controlled, surely they'd develop their own proprietary one (or worst case, buy out one of the western also-rans).

The point being that the west has already accepted it and is building tooling for it, yet it’s free. So they can’t be embargoed, but they can embrace, extend, and extinguish with massive subsidies and incentive.

I think everyone in this thread underestimates this part of ARM's business (from the F-1):

* Expand our System IP and SoC Offerings. To enable further improvements in performance and efficiency, we continue to develop a broader set of configurable systems IP offerings, including proven on-chip interconnect, security IP, memory controllers, and other design IP to be used with our processors, including the integration of multiple IP technologies into a subsystem and additional information to assist in fabrication. More recently, we have invested in a holistic, solution-focused approach to design, expanding beyond individual design IP elements to providing a more complete system. By delivering SoC solutions optimized for specific use cases, we can ensure that the entire system works together seamlessly to provide maximum performance and efficiency. At the same time, by designing an increasingly greater portion of the overall chip design, we are further reducing incremental development investment and risk borne by our customers while also enabling us to capture more value per device.*

ARM doesn't just give you the architecture, they give you a reference design that already works and then lets you customize it however you want.

Companies like Apple don't care about that, but MediaTek, NXP, etc. use it to speed the design process meaningfully.

ARM already does that though. Their dev systems like the Juno boards are ARM designed chips with ARM IP through and through covering just about every accelerator and integration niche. CPUs, NoC fabrics, GPIO, sound, just about every hardware interface master and slave, AI inference, display scanout, etc.

Integrators don't typically go all in on ARM IP though for a couple major reasons. 1) They want to provide some value add beyond the standard offerings or else why pick them over a competitor? 3) They have massive collections of IP blocks already that they don't have pay ARM for. Maybe it takes some engineering to convert to the next chip, but that's probably cheaper than what ARM is asking for.

Sure, I'm not saying that ARM is in a good position per se, but that RISC-V has way more catching up to do than people realize.

I am giving RISC-V 5 to 10 years to catch up in my estimates. I think that is fair. The momentum behind RISC-V is massive and even then I am not saying it is fast.

5 years is a flash in chip design. Initial design to tape-out is 3 years at the leading edge if you're really good.

Maybe in 5-10 years, RISC-V gains share in initial designs, but the semiconductor design process is loooong.

And if you're going to talk about Microcontrollers and simpler chips, keep in mind we had a bunch of other RISC architectures a decade ago that all lost to Cortex-M for simplicity/cost reasons (RIP MIPS).

I think RISC-V eats ARM's lunch at the low end across the board over the next 5 years. Financially that is okay in the near term for ARM as the major profits are all in the high end designs.

But all that will be left in a few years is the high end areas and where there is a lot of lock in to the ISA.

It isn't yet clear when RISC-V will be ready to compete at the highest end of things, but that is where Jim Keller comes in.

RISC-V is a classic market disruptor for ARM, just as ARM was a disruptor to Intel.

It's less than you would think. Despite having offerings in about every IP block segment about the only ARM IP blocks that get heavy use are the pieces that have some other ecosystem thing going on. PL011 uarts are de facto required for some initial consoles. Mali GPUs were being sold in what was frankly a move that needed some anti-trust scrutiny (ARM saw Apple taking the piss out of IMG and decided to go in for the kill by offering CPUs+GPU for cheaper than CPUs on their own, overnight destroying IMG's market). Beyond that it's easier to not pay ARM for their IP. NoC fabrics and IP blocks that touch pads are better coming relatively straight from the foundry. Simple serial controllers are essentially commodities at this point. Etc.

So RISC-V really only needs to focus on CPU cores to be an existential threat to ARM.

At this point their biggest most is probably the patents on AMBA specs, but if they tried hard to enforce those the industry would switch to something like TileLink in a relative heartbeat.

Unity IPO’ed three years ago. Their stock is down 80%, common among tech stock since money printer stopped. However now their plan to turn the tech company to cash cow and milk existing customers seem to have backfired.

A lot of games can not just drop Unity quickly. So a bunch will be forced into paying Unity. Also remember Apple just made Unity "the way" for making full screen VR apps on their new VR device. Don't underestimate how much Unity can make this way... while a lot will drop Unity many games simply can not in the medium term.

Exactly. Milk the cow until its dead and preferably little longer.

> if you go RISC-V, you are free to switch CPU providers.

That's not even true within the ARM ecosystem itself. The chips from Infineon are not source-code compatible with STM, STM is not compatible with Microchip, Microchip is not compatible with TI...

The problem is that the ARM core is just a portion of the architecture. Everything on top of that - GPIO, memory interfaces, timing, etc - is vendor specific, and will stay that way for RISC-V.

Not to mention, the chips also won't be electrically-compatible. Your hardware architecture can be as daunting to redesign as the code, if not more so.

>Everything on top of that - GPIO, memory interfaces, timing, etc - is vendor specific, and will stay that way for RISC-V.

Not as true for RISC-V, as there's efforts (some of them complete) to standardize interfaces to standard peripherals.

E.g. timers, gpios and watchdogs.

An open source ISA isn't the same as a design. They are radically different, in order to use an ISA you need IP design. The companies that are gaining ground with RISC-V are all largely IP vendors, which is exactly what Arm is. It's just shifting where the dollars go.

I like the idea of an open platform centered around an open standard - I don't know enough about the subject but I wonder if RISC-V is viable as a complete product?

Like, if we ignore the chip design aspects - is it guaranteed software compiled on one RISC-V chip will run on another RISC-V chip? (in the same way it does on ARM and amd64/x86?

What about hardware interoperability? PCI? UEFI/Boot semantics? Power management?

Who enforces that stuff for arm and x86 platforms?

> What about hardware interoperability? PCI? UEFI/Boot semantics? Power management?

Afraid I have bad news about ARM right there.

I'm interested in understanding and keeping up with this space - do you have any suggestions for resources to look at?

> What about hardware interoperability? PCI? UEFI/Boot semantics? Power management?

Refer to the RISC-V platform spec (ongoing).

It depends on other specs, some of which (like those related to the boot process) have already been ratified.

That's amazing - does that mean it's more complete than arm as a platform offering?

I don't think arm has anything standard around the boot process and vendors have various implementations