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Is the SiFive U74 open source? I know the RISC-V ISA is, but I thought the SiFive designs were proprietary.

stragies 6y ago
The processor maybe, but what about the e.g. USB3 controller, WIFI, etc, that can also freely snoop around your memory. Are there even open USB3 implementations?
- joana035 6y ago
  > that can also freely snoop around your memory. Can them? Even with IOMMU? EDIT: I don't think so.
  - chem83 6y ago
    Is there an IOMMU specification standardized on RISC-V yet? I think it's just some early proposals. Or proprietary designs that achieve similar functionality such as Hex Five and WorldGuard. Am I right?
gjsman-1000 6y ago
Open source refers solely to the software side of things in these groups and types of projects. Thus, all of the drivers and software you need to use the SiFive is open source and thus you can say it is an open source design. However, it is not an "open hardware" design in that the IP used to design the chip is not released.
- coder543 6y ago
  > However, it is not an "open hardware" design in that the IP used to design the chip is not released. The marketing page for the BeagleV specifically says "Open Hardware Design", but I agree that they probably didn't mean Open Hardware beyond just the PCB layout or something similar. It would be very surprising if they released the detailed schematics for the SiFive cores. Until there's some kind of common micro-fab standard where every major university can have a legit semiconductor fab for small scale operations, giving people the design doesn't really do much. I really wish that someone would work on the problem of making affordable, small-scale semiconductor fabrication possible on a reasonably modern node (<= 32nm). It's a hard problem... but everyone in the world being dependent on a few large fabs is also a hard problem.
  - jdkticom 6y ago
    Correct. This is open at the ISA, PCB and software level, not the chip RTL. Still, it is a step forward. For something more open at the RTL level, I'd look at Precuror (https://www.crowdsupply.com/sutajio-kosagi/precursor https://www.crowdsupply.com/sutajio-kosagi/precursor) right now. Speaking as someone at Beagle, we see this board as an important step to more openness in the ecosystem, especially helping software developers improve the state of open source for RISC-V. It is also just a really cool board. Beagle will do more to try to get more openness at the RTL-level moving forward, perhaps even with FPGA boards at an interim step. The shuttle services are starting to make releasing a new chip design in reasonably modern nodes more possible.
zozbot234 6y ago
Looks like their Hard IP is proprietary but based on open high-level designs such as Rocket and BOOM. The peripherals situation is mixed, but they've stated in the past that they're quite OK with using open designs whenever feasible.
- my123 6y ago
  The high-level design is proprietary too. As I said elsewhere, SiFive CPUs are just as closed as Arm ones, you just pay a royalty to SiFive instead of Arm.
  - zozbot234 6y ago
    > The high-level design is proprietary too. They have source code files for their 'Freedom' core designs up on GitHub under an Apache 2.x license. These can be directly used to evaluate their designs as FPGA soft-cores.
    - my123 6y ago
      The SoC, with the Rocket core used. This is very different from SiFive's own U series cores, which are proprietary.
      - zozbot234 6y ago
        SiFive has E-series (aka "Freedom Everywhere") and U-series (aka "Freedom Unleashed") cores, both of which seem to be based on Rocket. And they do provide high-level designs for both on their GitHub, under a free license.
        my123 6y ago
        High-level designs of the SoC, not of those cores themselves is public for some platforms. Based on whatever for the core doesn't matter, as the cores themselves in any case diverge quite a lot from Rocket.
  - 6y ago
ipodopt 6y ago
Some of them are open source: https://github.com/sifive/freedom https://github.com/sifive/freedom So this board has an open source CPU: https://www.sifive.com/boards/hifive1-rev-b https://www.sifive.com/boards/hifive1-rev-b This does not: https://www.sifive.com/boards/hifive-unmatched https://www.sifive.com/boards/hifive-unmatched Although, I get the feeling they will open source design on a rolling basis. Pure speculation.

The processor maybe, but what about the e.g. USB3 controller, WIFI, etc, that can also freely snoop around your memory. Are there even open USB3 implementations?

joana035 6y ago
> that can also freely snoop around your memory. Can them? Even with IOMMU? EDIT: I don't think so.
- chem83 6y ago
  Is there an IOMMU specification standardized on RISC-V yet? I think it's just some early proposals. Or proprietary designs that achieve similar functionality such as Hex Five and WorldGuard. Am I right?

gjsman-1000 6y ago

Open source refers solely to the software side of things in these groups and types of projects. Thus, all of the drivers and software you need to use the SiFive is open source and thus you can say it is an open source design. However, it is not an "open hardware" design in that the IP used to design the chip is not released.

coder543 6y ago
> However, it is not an "open hardware" design in that the IP used to design the chip is not released. The marketing page for the BeagleV specifically says "Open Hardware Design", but I agree that they probably didn't mean Open Hardware beyond just the PCB layout or something similar. It would be very surprising if they released the detailed schematics for the SiFive cores. Until there's some kind of common micro-fab standard where every major university can have a legit semiconductor fab for small scale operations, giving people the design doesn't really do much. I really wish that someone would work on the problem of making affordable, small-scale semiconductor fabrication possible on a reasonably modern node (<= 32nm). It's a hard problem... but everyone in the world being dependent on a few large fabs is also a hard problem.
- jdkticom 6y ago
  Correct. This is open at the ISA, PCB and software level, not the chip RTL. Still, it is a step forward. For something more open at the RTL level, I'd look at Precuror (https://www.crowdsupply.com/sutajio-kosagi/precursor https://www.crowdsupply.com/sutajio-kosagi/precursor) right now. Speaking as someone at Beagle, we see this board as an important step to more openness in the ecosystem, especially helping software developers improve the state of open source for RISC-V. It is also just a really cool board. Beagle will do more to try to get more openness at the RTL-level moving forward, perhaps even with FPGA boards at an interim step. The shuttle services are starting to make releasing a new chip design in reasonably modern nodes more possible.

zozbot234 6y ago

Looks like their Hard IP is proprietary but based on open high-level designs such as Rocket and BOOM. The peripherals situation is mixed, but they've stated in the past that they're quite OK with using open designs whenever feasible.

my123 6y ago
The high-level design is proprietary too. As I said elsewhere, SiFive CPUs are just as closed as Arm ones, you just pay a royalty to SiFive instead of Arm.
- zozbot234 6y ago
  > The high-level design is proprietary too. They have source code files for their 'Freedom' core designs up on GitHub under an Apache 2.x license. These can be directly used to evaluate their designs as FPGA soft-cores.
  - my123 6y ago
    The SoC, with the Rocket core used. This is very different from SiFive's own U series cores, which are proprietary.
    - zozbot234 6y ago
      SiFive has E-series (aka "Freedom Everywhere") and U-series (aka "Freedom Unleashed") cores, both of which seem to be based on Rocket. And they do provide high-level designs for both on their GitHub, under a free license.
      - my123 6y ago
        High-level designs of the SoC, not of those cores themselves is public for some platforms. Based on whatever for the core doesn't matter, as the cores themselves in any case diverge quite a lot from Rocket.
- 6y ago

ipodopt 6y ago

Some of them are open source: https://github.com/sifive/freedom https://github.com/sifive/freedom So this board has an open source CPU: https://www.sifive.com/boards/hifive1-rev-b https://www.sifive.com/boards/hifive1-rev-b This does not: https://www.sifive.com/boards/hifive-unmatched https://www.sifive.com/boards/hifive-unmatched Although, I get the feeling they will open source design on a rolling basis. Pure speculation.