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RISC-V doesn’t come with the patents needed to build a modern high performance CPU. Building modern CPUs isn’t about the ISA of Intel made the x86 ISA open to

RISC-V doesn’t come with the patents needed to build a modern high performance CPU. Building modern CPUs isn’t about the ISA of Intel made the x86 ISA open to all tomorrow you still would need a plethora of patents licensed to ship a CPU without being sued to oblivion.

audunw 6y ago
Do you have any examples of the kind of patents you would need to license? I don't anything in the ISA itself is covered by patents anymore. And the basic techniques for making a high performance CPU are getting quite old. Seems like a lot of the techniques used by desktop CPUs being released today have a a lot to do with advanced cache architectures, "AI" branch prediction, virtual memory, hypervisors, etc. A lot of these things will not be so relevant to a special purpose embedded CPU like this.
- dogma1138 6y ago
  Depends on what the embedded CPU is for, especially for more bespoke applications that may require optimization for specific tasks like encryption, networking and compression you’ll likely to hit a patent wall quite quickly. And in general building a high performance ALU, FPU, a modern MMU with virtualization and I/OMMU support, an efficient instruction decoder and register file are all covered by patents that are still in effect. Large companies that design their own cores cross license a shit tonne of patents between themselves and for everything else they hold each other at gun point. AMD and Intel quite likely violate each other’s patents all the time at least those that aren’t covered by the cross licensing agreement they just know that if they go to court neither of them will be able to put a CPU on the shelves for the next 3 decades. NVIDIA got patent slapped to oblivion when they wanted to emulate x86 on GPUs despite technically having an x86 license at the time (although Intel claimed it didn’t cover what NVIDIA was planning) and the fact that binary translation has been ruled not to infringe on ISA related patents. In general circumventing patents is expensive and if you don’t have a large enough patent portfolio to be able to plausibly claim how you’ve achieved a certain level of functionality you’ll always be at risk of claims and law suits. Until there will be a large consortium or industry leaders that are willing to share their patents for free or at an acceptable cost through a (F)RAND license with all members I don’t see RISC-V being a cheap version for anyone but the existing giants that already either license enough patents from others or have enough of their own to be bulletproof.
  - my123 6y ago
    Note that even Microsoft got warned by this: https://newsroom.intel.com/editorials/x86-approaching-40-still-going-strong/ https://newsroom.intel.com/editorials/x86-approaching-40-sti... for Windows on Arm including x86 backwards compatibility. However, guess that Microsoft has a big enough patent portfolio for Intel to not go beyond that threat...
    - dogma1138 6y ago
      Microsoft and Apple also not in direct competition with Intel, and Intel rather not lose more of their business in a pissing contest so I think it's treating them somewhat differently (tho if you don't protect your patents you kinda open yourself for future violations) NVIDIA on the other hand was and still is a direct threat to Intel in the datacenter.
      - jacobush 6y ago
        No, that's trademarks, you need to enforce them.
ldng 6y ago
Hum, on the other hand patents up to Pentium 4 should have expired, right ? So, you might not be able to have "modern" CPU, depending on your definition of modern, but yet be abble to build specialized CPU with decent performance I suppose.
- dogma1138 6y ago
  You still need modern IP for PCIe, modern memory, flash storage etc.
  - hajile 6y ago
    That's true, but I'd imagine a company like Western Digital has those patents and cross licensing agreements.
    - dogma1138 6y ago
      They might have some, but licensing from ARM gives you all in one neat package, and I’m not sure how much more economical it is to invest in RISC-V especially if you are smaller than WD. WD is still pretty darn huge and that is kinda the point, with ARM you can roll out cores cheaply without worrying about needing additional licenses. Until RISC-V will have an ecosystem of oven ready cores that can be licensed for essentially immediate tape out I’m not seeing it as a major threat to ARM. The biggest threat so far seems to be that ARM may have to lower its fees even further at least for its embedded cores as there aren’t any RISC-V designs out there that threaten their Application Processor uArch yet.
      - brucehoult 6y ago
        The HiFive Unmatched board with quad U74 cores is available to order now on Mouser or CrowdSupply, with Mouser saying they'll have stock on Jan 1. The U74 is very similar to an A55 without NEON. I suspect SiFive is probably going to put the FU-740 SoC itself on Mouser once they have sufficient supplies to fulfill board orders. Their U84 core was announced 12 months ago and is A72-equivalent (again excluding NEON). They way these things work there will probably be chips and boards available in another 12 months. The VIU75 core was also just announced as available for licensing. That's a U74 plus RISC-V Vector extension (more like SVE than NEON). Obviously ARM has already moved on from the A72 and they're up to A78 now with I think the A76 the latest actually shipping in devices (e.g. Samsung Galaxy S20). But RISC-V is catching up pretty quickly considering that four years ago there was no RISC-V chips shipping at all. Also A72 to A78 is just incremental improvements, much like Nehalem to Sandy Bridge to SkyLake in x86. Of course the newer ones are better, but there are plenty of people out there still happily using Sandy Bridge.

audunw 6y ago

Do you have any examples of the kind of patents you would need to license? I don't anything in the ISA itself is covered by patents anymore. And the basic techniques for making a high performance CPU are getting quite old. Seems like a lot of the techniques used by desktop CPUs being released today have a a lot to do with advanced cache architectures, "AI" branch prediction, virtual memory, hypervisors, etc. A lot of these things will not be so relevant to a special purpose embedded CPU like this.

dogma1138 6y ago
Depends on what the embedded CPU is for, especially for more bespoke applications that may require optimization for specific tasks like encryption, networking and compression you’ll likely to hit a patent wall quite quickly. And in general building a high performance ALU, FPU, a modern MMU with virtualization and I/OMMU support, an efficient instruction decoder and register file are all covered by patents that are still in effect. Large companies that design their own cores cross license a shit tonne of patents between themselves and for everything else they hold each other at gun point. AMD and Intel quite likely violate each other’s patents all the time at least those that aren’t covered by the cross licensing agreement they just know that if they go to court neither of them will be able to put a CPU on the shelves for the next 3 decades. NVIDIA got patent slapped to oblivion when they wanted to emulate x86 on GPUs despite technically having an x86 license at the time (although Intel claimed it didn’t cover what NVIDIA was planning) and the fact that binary translation has been ruled not to infringe on ISA related patents. In general circumventing patents is expensive and if you don’t have a large enough patent portfolio to be able to plausibly claim how you’ve achieved a certain level of functionality you’ll always be at risk of claims and law suits. Until there will be a large consortium or industry leaders that are willing to share their patents for free or at an acceptable cost through a (F)RAND license with all members I don’t see RISC-V being a cheap version for anyone but the existing giants that already either license enough patents from others or have enough of their own to be bulletproof.
- my123 6y ago
  Note that even Microsoft got warned by this: https://newsroom.intel.com/editorials/x86-approaching-40-still-going-strong/ https://newsroom.intel.com/editorials/x86-approaching-40-sti... for Windows on Arm including x86 backwards compatibility. However, guess that Microsoft has a big enough patent portfolio for Intel to not go beyond that threat...
  - dogma1138 6y ago
    Microsoft and Apple also not in direct competition with Intel, and Intel rather not lose more of their business in a pissing contest so I think it's treating them somewhat differently (tho if you don't protect your patents you kinda open yourself for future violations) NVIDIA on the other hand was and still is a direct threat to Intel in the datacenter.
    - jacobush 6y ago
      No, that's trademarks, you need to enforce them.

ldng 6y ago

Hum, on the other hand patents up to Pentium 4 should have expired, right ? So, you might not be able to have "modern" CPU, depending on your definition of modern, but yet be abble to build specialized CPU with decent performance I suppose.

dogma1138 6y ago
You still need modern IP for PCIe, modern memory, flash storage etc.
- hajile 6y ago
  That's true, but I'd imagine a company like Western Digital has those patents and cross licensing agreements.
  - dogma1138 6y ago
    They might have some, but licensing from ARM gives you all in one neat package, and I’m not sure how much more economical it is to invest in RISC-V especially if you are smaller than WD. WD is still pretty darn huge and that is kinda the point, with ARM you can roll out cores cheaply without worrying about needing additional licenses. Until RISC-V will have an ecosystem of oven ready cores that can be licensed for essentially immediate tape out I’m not seeing it as a major threat to ARM. The biggest threat so far seems to be that ARM may have to lower its fees even further at least for its embedded cores as there aren’t any RISC-V designs out there that threaten their Application Processor uArch yet.
    - brucehoult 6y ago
      The HiFive Unmatched board with quad U74 cores is available to order now on Mouser or CrowdSupply, with Mouser saying they'll have stock on Jan 1. The U74 is very similar to an A55 without NEON. I suspect SiFive is probably going to put the FU-740 SoC itself on Mouser once they have sufficient supplies to fulfill board orders. Their U84 core was announced 12 months ago and is A72-equivalent (again excluding NEON). They way these things work there will probably be chips and boards available in another 12 months. The VIU75 core was also just announced as available for licensing. That's a U74 plus RISC-V Vector extension (more like SVE than NEON). Obviously ARM has already moved on from the A72 and they're up to A78 now with I think the A76 the latest actually shipping in devices (e.g. Samsung Galaxy S20). But RISC-V is catching up pretty quickly considering that four years ago there was no RISC-V chips shipping at all. Also A72 to A78 is just incremental improvements, much like Nehalem to Sandy Bridge to SkyLake in x86. Of course the newer ones are better, but there are plenty of people out there still happily using Sandy Bridge.