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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 prec

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.
  - desiarnezjr 4y ago
    Apple co-founded ARM. I recall somewhere that they did have a very special license, but can't recall the details.
  - _ph_ 4y ago
    As Apple is a co-founder of ARM and holds and architectural license, I think the chances are high, that they neither pay any or significant royalties and have a lot of freedom. As could be seen in the special switch making the memory semantics of the Apple Silicon match that of x86, making the job of Rosetta easier.
    - throwawaylinux 4y ago
      Apple holds an architectural license, but I've never heard it suggested they can avoid paying royalties to ARM before. Doesn't seem very likely to me.
  - garaetjjte 4y ago
    >I'm not sure about that. I think licensees are bound by certain requirements to implement the architecture faithfully Apple designs already deviate from ARM64 specifications, like adding custom instructions: https://github.com/AsahiLinux/docs/wiki/HW:Apple-Instructions https://github.com/AsahiLinux/docs/wiki/HW:Apple-Instruction...
klelatti 4y ago
As you know Arm makes most of its money selling actual designs, not the ISA. I suspect Apple pays very small fees which are not material in the context of the Mac. For that it probably gets access to the full range of Arm IP, including for example the IP associated with big.LITTLE - and there are likely to be others. There are two areas where RISC-V, for example, does have present a clear advantage for firms: where firms want to innovate on top on an ISA (eg Tenstorrent) or who want to shave cents off their BOM (eg WD).
- throwawaylinux 4y ago
  ARM makes most of its money in royalties, not licensing. Under royalties, how much comes from chips that use their designs and how much from ones that don't, I don't know. Do they make that data available? > I suspect Apple pays very small fees which are not material in the context of the Mac. Why do you suspect they are very small?
  - klelatti 4y ago
    There were at a minimum 1.5 billion A series based CPUs sold last year - possibly a lot more. Arm’s total royalty sales were $1.5bn. I think we can safely say that the fees Apple pays - with its architecture license - are not material in the context of the Mac.
    - throwawaylinux 4y ago
      > There were at a minimum 1.5 billion A series based CPUs sold last year - possibly a lot more. Arm’s total royalty sales were $1.5bn. I think we can safely say that the fees Apple pays - with its architecture license - are not material in the context of the Mac. I don't see how that follows. You don't know what their royalty arrangement is. It's probably related to the value of the chip sold. If they sell 20 million macs a year and pay ARM 2 bucks a chip that's 40 million every year. If macs have a gross profit of a couple of billion that's not insignificant. Could be 5% of that. Not to mention several hundred million a year for iphones. Lot of money to pay to be locked into a proprietary ISA when you almost entirely support your own ecosystem, compilers, OSes, etc anyway.

_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.
- desiarnezjr 4y ago
  Apple co-founded ARM. I recall somewhere that they did have a very special license, but can't recall the details.
- _ph_ 4y ago
  As Apple is a co-founder of ARM and holds and architectural license, I think the chances are high, that they neither pay any or significant royalties and have a lot of freedom. As could be seen in the special switch making the memory semantics of the Apple Silicon match that of x86, making the job of Rosetta easier.
  - throwawaylinux 4y ago
    Apple holds an architectural license, but I've never heard it suggested they can avoid paying royalties to ARM before. Doesn't seem very likely to me.
- garaetjjte 4y ago
  >I'm not sure about that. I think licensees are bound by certain requirements to implement the architecture faithfully Apple designs already deviate from ARM64 specifications, like adding custom instructions: https://github.com/AsahiLinux/docs/wiki/HW:Apple-Instructions https://github.com/AsahiLinux/docs/wiki/HW:Apple-Instruction...

klelatti 4y ago

As you know Arm makes most of its money selling actual designs, not the ISA. I suspect Apple pays very small fees which are not material in the context of the Mac. For that it probably gets access to the full range of Arm IP, including for example the IP associated with big.LITTLE - and there are likely to be others. There are two areas where RISC-V, for example, does have present a clear advantage for firms: where firms want to innovate on top on an ISA (eg Tenstorrent) or who want to shave cents off their BOM (eg WD).

throwawaylinux 4y ago
ARM makes most of its money in royalties, not licensing. Under royalties, how much comes from chips that use their designs and how much from ones that don't, I don't know. Do they make that data available? > I suspect Apple pays very small fees which are not material in the context of the Mac. Why do you suspect they are very small?
- klelatti 4y ago
  There were at a minimum 1.5 billion A series based CPUs sold last year - possibly a lot more. Arm’s total royalty sales were $1.5bn. I think we can safely say that the fees Apple pays - with its architecture license - are not material in the context of the Mac.
  - throwawaylinux 4y ago
    > There were at a minimum 1.5 billion A series based CPUs sold last year - possibly a lot more. Arm’s total royalty sales were $1.5bn. I think we can safely say that the fees Apple pays - with its architecture license - are not material in the context of the Mac. I don't see how that follows. You don't know what their royalty arrangement is. It's probably related to the value of the chip sold. If they sell 20 million macs a year and pay ARM 2 bucks a chip that's 40 million every year. If macs have a gross profit of a couple of billion that's not insignificant. Could be 5% of that. Not to mention several hundred million a year for iphones. Lot of money to pay to be locked into a proprietary ISA when you almost entirely support your own ecosystem, compilers, OSes, etc anyway.