5 ms·

This seems very, very unlikely to me. RISC-V is a very similar architecture to AArch64; I haven't heard a reason to expect it to have improved performance or ef

This seems very, very unlikely to me. RISC-V is a very similar architecture to AArch64; I haven't heard a reason to expect it to have improved performance or efficiency. (Its only distinguishing feature (that I know of) is compressed instructions -- which ARM used to have (THUMB mode) before dropping support in AArch64, so presumably it doesn't help on Apple's systems with their huge caches and high memory bandwidth.) Rather, RISC-V's primary advantage over ARM is its openness; vendors can do whatever they want with the ISA without having to pay license fees or maintain compatibility. But this doesn't affect Apple at all; they co-founded ARM, and they have a huge amount of influence over the direction of the architecture along with some sort of special license that allows them to do things other CPU vendors aren't allowed to do (https://news.ycombinator.com/item?id=29782840 https://news.ycombinator.com/item?id=29782840, https://twitter.com/stuntpants/status/1346470705446092811 https://twitter.com/stuntpants/status/1346470705446092811). Developing an entirely new high-end CPU mircoarchitecture takes many years and many billions of dollars. It's not something Apple's going to do unless they have a very, very good reason -- and RISC-V being really cool is unfortunately not a good enough reason.

keepquestioning 4y ago
Apple will not have to pay ARM for licensing
- stu2b50 4y ago
  Apple doesn't pay ARM for licensing.
  - senttoschool 4y ago
    Even if Apple does, it's probably peanuts. Apple has invested billions to make a full transition to ARM. I'd think that they would have to spend at least $50 billion or more to redesign all the Apple Silicon from the iPhone to the Mac Pro, rewrite 5 or 6 operating systems, and beg developers to recompile their apps. It'd be a nightmare. I think Apple will stay on ARM for at least 20 years...
    - deleted 4y ago
      [deleted]
    - desiarnezjr 4y ago
      Why just 20 years? This direction gives full control of a silicon roadmap. They can make it whatever they want or need. My guess is they have a more specific roadmap than even Intel or AMD at this point, as they're not commodity processors, but now engineered for a very specific purpose.
FullyFunctional 4y ago
I agree, it’s seems unlikely they will have another transition as they now control their own destiny. The fact that Arm64 doesn’t have compressed instructions is obviously a very deliberate choice, thus I can’t agree with the notion that RISC-V compressed instructions could be a potential “advantage” over Arm64. Their absence is a massive advantage in many ways that I have explained over and over on HN and it’s the single biggest stupidity in RISC-V for high-end perf (not microcontrollers).
throwawaylinux 4y ago
ARM instruction set licensing is a drag, an inefficiency. ARMv8 is a nice ISA, and the work that architects do is critical, and it's not easy to develop a precise, clean, extensible, and relatively bug free ISA. But there is relatively little real innovation in it. It's a pretty conventional RISC, warmed over for the modern era. In fact no ISA has any real magic, that's all in the silicon. There's certainly not hundreds of millions of dollars per year worth. That money is only paid because of the proprietary lock-in and ecosystem around the ISA, which is similar to the proprietary software model, so at some point it would be easy to imagine large chunks of the industry deciding to break away and go to something more open. It may not inevitably displace ARM entirely, and ARM Ltd might change their ways or open their ISA to prevent it. But it could easily happen too, in the next decade or so.
- _ph_ 4y ago
  This certainly applies to random manufacturers, but not necessarily Apple. Do they pay royalties to ARM at all? And of course, they could create any ISA extension, if they wanted. But currently they seem to be heading more into the direction of creating additional compute units (like the neural processors) rather than adding new instructions to the CPUs.
  - throwawaylinux 4y ago
    > This certainly applies to random manufacturers, but not necessarily Apple. Do they pay royalties to ARM at all? I don't know if there are any public details about license and royalty structure for Apple, but this is ARM Ltd's core business and it's how they make their money. So, probably. > And of course, they could create any ISA extension, if they wanted. I'm not sure about that. I think licensees are bound by certain requirements to implement the architecture faithfully. Now Apple obviously has a huge sway and could lobby ARM to make changes it wants. But it does not necessarily have final control of that either. > But currently they seem to be heading more into the direction of creating additional compute units (like the neural processors) rather than adding new instructions to the CPUs.
    - 4y ago

keepquestioning 4y ago

Apple will not have to pay ARM for licensing

stu2b50 4y ago
Apple doesn't pay ARM for licensing.
- senttoschool 4y ago
  Even if Apple does, it's probably peanuts. Apple has invested billions to make a full transition to ARM. I'd think that they would have to spend at least $50 billion or more to redesign all the Apple Silicon from the iPhone to the Mac Pro, rewrite 5 or 6 operating systems, and beg developers to recompile their apps. It'd be a nightmare. I think Apple will stay on ARM for at least 20 years...
  - deleted 4y ago
    [deleted]
  - desiarnezjr 4y ago
    Why just 20 years? This direction gives full control of a silicon roadmap. They can make it whatever they want or need. My guess is they have a more specific roadmap than even Intel or AMD at this point, as they're not commodity processors, but now engineered for a very specific purpose.

FullyFunctional 4y ago

I agree, it’s seems unlikely they will have another transition as they now control their own destiny. The fact that Arm64 doesn’t have compressed instructions is obviously a very deliberate choice, thus I can’t agree with the notion that RISC-V compressed instructions could be a potential “advantage” over Arm64. Their absence is a massive advantage in many ways that I have explained over and over on HN and it’s the single biggest stupidity in RISC-V for high-end perf (not microcontrollers).

throwawaylinux 4y ago

ARM instruction set licensing is a drag, an inefficiency. ARMv8 is a nice ISA, and the work that architects do is critical, and it's not easy to develop a precise, clean, extensible, and relatively bug free ISA. But there is relatively little real innovation in it. It's a pretty conventional RISC, warmed over for the modern era. In fact no ISA has any real magic, that's all in the silicon. There's certainly not hundreds of millions of dollars per year worth. That money is only paid because of the proprietary lock-in and ecosystem around the ISA, which is similar to the proprietary software model, so at some point it would be easy to imagine large chunks of the industry deciding to break away and go to something more open. It may not inevitably displace ARM entirely, and ARM Ltd might change their ways or open their ISA to prevent it. But it could easily happen too, in the next decade or so.

_ph_ 4y ago
This certainly applies to random manufacturers, but not necessarily Apple. Do they pay royalties to ARM at all? And of course, they could create any ISA extension, if they wanted. But currently they seem to be heading more into the direction of creating additional compute units (like the neural processors) rather than adding new instructions to the CPUs.
- throwawaylinux 4y ago
  > This certainly applies to random manufacturers, but not necessarily Apple. Do they pay royalties to ARM at all? I don't know if there are any public details about license and royalty structure for Apple, but this is ARM Ltd's core business and it's how they make their money. So, probably. > And of course, they could create any ISA extension, if they wanted. I'm not sure about that. I think licensees are bound by certain requirements to implement the architecture faithfully. Now Apple obviously has a huge sway and could lobby ARM to make changes it wants. But it does not necessarily have final control of that either. > But currently they seem to be heading more into the direction of creating additional compute units (like the neural processors) rather than adding new instructions to the CPUs.
  - 4y ago