3 ms·

~~I would imagine so. To my knowledge it's an FPGA with their core IP running on it. You could probably get away without any kernel blobs but the firmware at th

~~I would imagine so. To my knowledge it's an FPGA with their core IP running on it. You could probably get away without any kernel blobs but the firmware at the very least is going to need a binary blob to load their IP.~~ Edit: I stand corrected and should have read more into the product spec for this release before speaking. They have a proper ASIC now so I can't quite say without reading more into their docs. Note: ~~ is strikethrough text but apparently that doesn't work on HN

marcodiego 5y ago
Is it at least stored in ROM? I mean does it need proprietary blobs on software?
- CuriousCosmic 5y ago
  Scratch what I've said. Some other comments have enlightened me that this is actually a proper SOC so I can't answer this properly. In the past they've used FPGAs (IP cores are their primary business) for dev boards but it looks like they have reached sufficient momentum to justify a dedicated ASIC run.
ch_123 5y ago
It's not an FPGA, it has a dedicated SoC and some I/O controller chips. https://sifive.cdn.prismic.io/sifive/4f0048e8-1d35-4a1c-94ec-49a1021de21a_bill-of-materials-hifive-unmatched-3b0.pdf https://sifive.cdn.prismic.io/sifive/4f0048e8-1d35-4a1c-94ec...
- CuriousCosmic 5y ago
  Interesting. Apologies then. This was a bad assumption on my part. Is this the first time they've made their own custom SOC? To my knowledge their business is FPGA IP and previous boards used FPGAs with the IP flashed onto them.
  - ch_123 5y ago
    No, they have released a number of designs before - including the "Unleashed" [1] and "Hi Five" [2] which are both SoC designs as well. The Unleashed had an optional FPGA add-on, but it was not part of the main CPU. My reading is that they are aiming for real hardware implementations and not just FPGA. They have also licensed their designs to various third parties. I'm not sure how many have been turned into "real" hardware though. [1] https://www.sifive.com/boards/hifive-unleashed https://www.sifive.com/boards/hifive-unleashed [2] https://www.sifive.com/boards/hifive1-rev-b https://www.sifive.com/boards/hifive1-rev-b
foxfluff 5y ago
How did you come to the conclusion that it is an FPGA? I'm not finding any reference to an fpga in datasheet, schematics, documentation, or product brief.
- CuriousCosmic 5y ago
  Ahh. SiFive's primary business is selling their cores as FPGA IP. Previous boards used FPGAs with IP flashed on them so I naively assumed this board was the same.
  - ansible 5y ago
    > SiFive's primary business is selling their cores as FPGA IP. Their primary business is selling IP to be incorporated into SoCs and other chip designs. The FPGA market is very limited by comparison.
brucehoult 5y ago
Soft cores in FPGAs typically run at 100 MHz or less -- often 25 or 50 MHz for sophisticated OoO designs. SiFive's December 2016 "HiFive1" had a 320 MHz 32 bit SoC with one in-order 32 bit core. SiFive's early 2018 "HiFive Unleashed" had an SoC with five in-order 1.0 - 1.5 GHz (mine has worked stable at 1.45 GHz for 3+ years) cores. This "HiFive Unmatched" has an SoC with five dual issue in-order 1.0 to 1.5 GHz cores (mine works fine at 1.5). We're talking about 30 times faster MHz than an FPGA soft core would be. SiFive have never not had "proper" SoCs. Their business is selling IP for people to use to make SoCs. They provide early access to cores running on FPGAs at a small fraction of SoC speed to customers for evaluation purposes.

marcodiego 5y ago

Is it at least stored in ROM? I mean does it need proprietary blobs on software?

CuriousCosmic 5y ago
Scratch what I've said. Some other comments have enlightened me that this is actually a proper SOC so I can't answer this properly. In the past they've used FPGAs (IP cores are their primary business) for dev boards but it looks like they have reached sufficient momentum to justify a dedicated ASIC run.

ch_123 5y ago

It's not an FPGA, it has a dedicated SoC and some I/O controller chips. https://sifive.cdn.prismic.io/sifive/4f0048e8-1d35-4a1c-94ec-49a1021de21a_bill-of-materials-hifive-unmatched-3b0.pdf https://sifive.cdn.prismic.io/sifive/4f0048e8-1d35-4a1c-94ec...

CuriousCosmic 5y ago
Interesting. Apologies then. This was a bad assumption on my part. Is this the first time they've made their own custom SOC? To my knowledge their business is FPGA IP and previous boards used FPGAs with the IP flashed onto them.
- ch_123 5y ago
  No, they have released a number of designs before - including the "Unleashed" [1] and "Hi Five" [2] which are both SoC designs as well. The Unleashed had an optional FPGA add-on, but it was not part of the main CPU. My reading is that they are aiming for real hardware implementations and not just FPGA. They have also licensed their designs to various third parties. I'm not sure how many have been turned into "real" hardware though. [1] https://www.sifive.com/boards/hifive-unleashed https://www.sifive.com/boards/hifive-unleashed [2] https://www.sifive.com/boards/hifive1-rev-b https://www.sifive.com/boards/hifive1-rev-b

foxfluff 5y ago

How did you come to the conclusion that it is an FPGA? I'm not finding any reference to an fpga in datasheet, schematics, documentation, or product brief.

CuriousCosmic 5y ago
Ahh. SiFive's primary business is selling their cores as FPGA IP. Previous boards used FPGAs with IP flashed on them so I naively assumed this board was the same.
- ansible 5y ago
  > SiFive's primary business is selling their cores as FPGA IP. Their primary business is selling IP to be incorporated into SoCs and other chip designs. The FPGA market is very limited by comparison.

brucehoult 5y ago

Soft cores in FPGAs typically run at 100 MHz or less -- often 25 or 50 MHz for sophisticated OoO designs. SiFive's December 2016 "HiFive1" had a 320 MHz 32 bit SoC with one in-order 32 bit core. SiFive's early 2018 "HiFive Unleashed" had an SoC with five in-order 1.0 - 1.5 GHz (mine has worked stable at 1.45 GHz for 3+ years) cores. This "HiFive Unmatched" has an SoC with five dual issue in-order 1.0 to 1.5 GHz cores (mine works fine at 1.5). We're talking about 30 times faster MHz than an FPGA soft core would be. SiFive have never not had "proper" SoCs. Their business is selling IP for people to use to make SoCs. They provide early access to cores running on FPGAs at a small fraction of SoC speed to customers for evaluation purposes.