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ARM seems to be half-way moving in this direction. They allowed "royalty free" licenses to educational institutions for some of their low end M0/3/4 cores. Bu

ARM seems to be half-way moving in this direction. They allowed "royalty free" licenses to educational institutions for some of their low end M0/3/4 cores. But yeah, I think you're right. The cool thing about RISC-V is you can just pick up the ISA and run with it. I'm pretty sure the Rocket core generator is released under a BSD license. SiFive sort of makes sense if you want to integrate proprietary IP with open IP, and some people do actually want to do that. I don't know if there's enough demand for that, though. But yeah. Even though we have compilers, it's not like you can spin up support for a new ISA in the drop of a hat. If you launched a project with a StarFive part and then decided you wanted to use SiFive IP, you should be able to use the same tooling. The impact of that shouldn't be under-estimated.

RetroTechie 3y ago
That's an important advantage: go Arm, and ultimately you'll be dealing with Arm (the IP licensing company), or with a 3rd party which deals with them. Go x86, and you'll end up dealing with Intel, or AMD (okay, there's Via & maybe a few makers of legacy x86 parts). Go RISC-V, and roll your own or pick from a growing list of vendors, are both valid options. And switch supplier while keeping your toolchain ecosystem. I'd expect at least that this will spur innovation in the field. Likely increase consumer choice. More suppliers of [insert product type here] is almost always a good thing.
- pjmlp 3y ago
  RISC-V is only a basic CPU specification, everything else is vendor specific.
  - snvzz 3y ago
    RISC-V, as of current ratified specifications, is anything but basic: It has feature parity with x86 and ARM. And the specs extend further to non-ISA, such as standardizing boot process and platform.
    - pjmlp 3y ago
      If we forget about everything else needed to put that paper specification on a real motherboard.
      - adgjlsfhk1 3y ago
        The important part is from a software perspective, none of that stuff matters much. The benefit of RiscV is you can be sure that your low level software (e.g. an OS or HPC thing that requires hand coded assembly) won't be tied to a specific company's hardware.
        OhMeadhbh 3y ago
        I read your comment to imply that the ISA is the only thing that matters since that's what defines the software interface and that software is the only thing that matters. If that is what you're saying, I think you're wrong. As to the low level hand coded assembly. There's a fair amount of stuff in the Intel architecture that's not officially published. There are tools (from Intel) like VTune and the Intel C compilers that use non-published interfaces to optimize C or assembly, sometimes significantly. It is true you can write software without them, but many people purchase these Intel tools to make sure their systems run quickly and efficiently. I can't remember if the SiFive U-X4 core equivalents were defined in the open RISC-V specs or as part of SiFive specific interfaces. If the former, then your point is even stronger. If the latter, your point is still valid, though modulo the impact of having relied on a SiFive specific interface.
        pjmlp 3y ago
        Ignoring extensions and motherboard features used from userspace.
- OhMeadhbh 3y ago
  Or... like my team did... you can design your own IP that specifically fits your needs.

RetroTechie 3y ago

That's an important advantage: go Arm, and ultimately you'll be dealing with Arm (the IP licensing company), or with a 3rd party which deals with them. Go x86, and you'll end up dealing with Intel, or AMD (okay, there's Via & maybe a few makers of legacy x86 parts). Go RISC-V, and roll your own or pick from a growing list of vendors, are both valid options. And switch supplier while keeping your toolchain ecosystem. I'd expect at least that this will spur innovation in the field. Likely increase consumer choice. More suppliers of [insert product type here] is almost always a good thing.

pjmlp 3y ago
RISC-V is only a basic CPU specification, everything else is vendor specific.
- snvzz 3y ago
  RISC-V, as of current ratified specifications, is anything but basic: It has feature parity with x86 and ARM. And the specs extend further to non-ISA, such as standardizing boot process and platform.
  - pjmlp 3y ago
    If we forget about everything else needed to put that paper specification on a real motherboard.
    - adgjlsfhk1 3y ago
      The important part is from a software perspective, none of that stuff matters much. The benefit of RiscV is you can be sure that your low level software (e.g. an OS or HPC thing that requires hand coded assembly) won't be tied to a specific company's hardware.
      - OhMeadhbh 3y ago
        I read your comment to imply that the ISA is the only thing that matters since that's what defines the software interface and that software is the only thing that matters. If that is what you're saying, I think you're wrong. As to the low level hand coded assembly. There's a fair amount of stuff in the Intel architecture that's not officially published. There are tools (from Intel) like VTune and the Intel C compilers that use non-published interfaces to optimize C or assembly, sometimes significantly. It is true you can write software without them, but many people purchase these Intel tools to make sure their systems run quickly and efficiently. I can't remember if the SiFive U-X4 core equivalents were defined in the open RISC-V specs or as part of SiFive specific interfaces. If the former, then your point is even stronger. If the latter, your point is still valid, though modulo the impact of having relied on a SiFive specific interface.
      - pjmlp 3y ago
        Ignoring extensions and motherboard features used from userspace.
OhMeadhbh 3y ago
Or... like my team did... you can design your own IP that specifically fits your needs.