4 ms·

Reference to support this? Plus you seem to imply that Apple has done this without Arm's consent which seems unlikely and even if so I would be astonished if t

Reference to support this? Plus you seem to imply that Apple has done this without Arm's consent which seems unlikely and even if so I would be astonished if that were in the public domain.

saagarjha 6y ago
I have no idea what Arm’s involvement is in all this, but from the outside it has consistently seemed like Apple launches chips that don’t follow what is documented and then the requirements invariably change soon after. Just off the top of my head, they’ve been shipping their own custom memory compression instructions for a while now, and I am pretty sure their chips dropped support for 4K granules much earlier than the rules claimed this was acceptable. AMX showed up in A13, I believe? Which would be just before the linked article is dated.
- socialdemocrat 6y ago
  What is a memory compression instruction? You mean their CPUs have special machine code instructions as part of their ISA for compressing segments of memory? Or do you mean something more akin to the Thumb format but for ARM-64?
  - saagarjha 6y ago
    > You mean their CPUs have special machine code instructions as part of their ISA for compressing segments of memory? Yes.
- klelatti 6y ago
  > I have no idea what Arm’s involvement is in all this But you implied that Apple flouted what was permitted by Arm. > Just off the top of my head That's not a reference. As others have commented its much, much more likely that Apple and Arm have a very close relationship and that Apple are just at the leading edge.
  - saagarjha 6y ago
    I did not imply that. My comment was a response to the claim that Arm started allowing this in 2019 when Apple clearly was doing this earlier. For all I know the relationship is that Apple just writes the standard and tells Arm to publish it. I have no idea what issues you had with my examples but if you describe them perhaps I can make them acceptable to you?
    - klelatti 6y ago
      I'm genuinely interested in the point you make about the these instructions but it's not helpful to mention something like this without a link to more information. On the first point you said 'Apple doesn't care' which I read as Apple doesn't care about the licensing rules - if you meant something else then fine but I think most people would read it that way.
      - saagarjha 6y ago
        I meant it in the way of "I don't think Apple has to care" since they do not follow them–what I do not know is if Apple has some other agreement in place, or they are violating something. For the instructions: the reason I didn't provide a link is because it would be very hard for me to do so, as these instructions are proprietary and undocumented, plus Apple strips out this code from their open source releases. The best I could find in the latest tarball is a definition for __ARM_WKDM_ISA_AVAILABLE__ for the Monsoon cores inside of A11: https://github.com/apple-open-source-mirror/xnu/blob/65d5be84e21bccbae44730ddb3b307a701b0351a/osfmk/arm/proc_reg.h#L162 https://github.com/apple-open-source-mirror/xnu/blob/65d5be8...
simonh 6y ago
I don't know the contractual terms myself, but I suspect that if Apple is only doing this internally for their own products, it may well be none of ARM's business. It's only an issue if Apple sells their processors to other companies as components. In that case they are required to comply with ARM's certification requirements, because ARM doesn't want the market for ARM cpus to become fragmented. If Apple are only using these CPUs for their internal products I don't think those requirements apply. It's a bit like the way the GPL has requirements that apply if you distribute the software (you have to release source code), but if you use your modified code internally the requirement doesn't apply. In this case "distributing" is equivalent to selling the CPUs as components, in contrast to using them in your own products (even ones you sell to customers) which counts as internal use and so the requirement doesn't apply.
GeekyBear 6y ago
>Apple has done this without Arm's consent which seems unlikely On the contrary, ARM has long worked closely with one or more licensees when developing new features. >ARM picks 2-3 lead licensees for each market segment and works closely with them. This narrows down the pool of initial partners to a manageable number and also ensures that anyone who is picked is up to the task of successfully getting a new core to market correctly. The partners get about a year lead time to market, critical for some, far less important for others. https://semiaccurate.com/2013/08/07/a-long-look-at-how-arm-licenses-chips/ https://semiaccurate.com/2013/08/07/a-long-look-at-how-arm-l...

Reference to support this? Plus you seem to imply that Apple has done this without Arm's consent which seems unlikely and even if so I would be astonished if that were in the public domain.

saagarjha 6y ago

I have no idea what Arm’s involvement is in all this, but from the outside it has consistently seemed like Apple launches chips that don’t follow what is documented and then the requirements invariably change soon after. Just off the top of my head, they’ve been shipping their own custom memory compression instructions for a while now, and I am pretty sure their chips dropped support for 4K granules much earlier than the rules claimed this was acceptable. AMX showed up in A13, I believe? Which would be just before the linked article is dated.

socialdemocrat 6y ago
What is a memory compression instruction? You mean their CPUs have special machine code instructions as part of their ISA for compressing segments of memory? Or do you mean something more akin to the Thumb format but for ARM-64?
- saagarjha 6y ago
  > You mean their CPUs have special machine code instructions as part of their ISA for compressing segments of memory? Yes.
klelatti 6y ago
> I have no idea what Arm’s involvement is in all this But you implied that Apple flouted what was permitted by Arm. > Just off the top of my head That's not a reference. As others have commented its much, much more likely that Apple and Arm have a very close relationship and that Apple are just at the leading edge.
- saagarjha 6y ago
  I did not imply that. My comment was a response to the claim that Arm started allowing this in 2019 when Apple clearly was doing this earlier. For all I know the relationship is that Apple just writes the standard and tells Arm to publish it. I have no idea what issues you had with my examples but if you describe them perhaps I can make them acceptable to you?
  - klelatti 6y ago
    I'm genuinely interested in the point you make about the these instructions but it's not helpful to mention something like this without a link to more information. On the first point you said 'Apple doesn't care' which I read as Apple doesn't care about the licensing rules - if you meant something else then fine but I think most people would read it that way.
    - saagarjha 6y ago
      I meant it in the way of "I don't think Apple has to care" since they do not follow them–what I do not know is if Apple has some other agreement in place, or they are violating something. For the instructions: the reason I didn't provide a link is because it would be very hard for me to do so, as these instructions are proprietary and undocumented, plus Apple strips out this code from their open source releases. The best I could find in the latest tarball is a definition for __ARM_WKDM_ISA_AVAILABLE__ for the Monsoon cores inside of A11: https://github.com/apple-open-source-mirror/xnu/blob/65d5be84e21bccbae44730ddb3b307a701b0351a/osfmk/arm/proc_reg.h#L162 https://github.com/apple-open-source-mirror/xnu/blob/65d5be8...

simonh 6y ago

I don't know the contractual terms myself, but I suspect that if Apple is only doing this internally for their own products, it may well be none of ARM's business. It's only an issue if Apple sells their processors to other companies as components. In that case they are required to comply with ARM's certification requirements, because ARM doesn't want the market for ARM cpus to become fragmented. If Apple are only using these CPUs for their internal products I don't think those requirements apply. It's a bit like the way the GPL has requirements that apply if you distribute the software (you have to release source code), but if you use your modified code internally the requirement doesn't apply. In this case "distributing" is equivalent to selling the CPUs as components, in contrast to using them in your own products (even ones you sell to customers) which counts as internal use and so the requirement doesn't apply.

GeekyBear 6y ago

>Apple has done this without Arm's consent which seems unlikely On the contrary, ARM has long worked closely with one or more licensees when developing new features. >ARM picks 2-3 lead licensees for each market segment and works closely with them. This narrows down the pool of initial partners to a manageable number and also ensures that anyone who is picked is up to the task of successfully getting a new core to market correctly. The partners get about a year lead time to market, critical for some, far less important for others. https://semiaccurate.com/2013/08/07/a-long-look-at-how-arm-licenses-chips/ https://semiaccurate.com/2013/08/07/a-long-look-at-how-arm-l...