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Okay, so is there actual documentation for the SoC used on this critter? I mean a full Databook / Technical Reference Manual, not maybe 30 pages of overview, m

Okay, so is there actual documentation for the SoC used on this critter? I mean a full Databook / Technical Reference Manual, not maybe 30 pages of overview, maybe a list of register base addresses (if you're lucky), and a pile of Linux kernel patches (upstream if you're lucky, but still of less value to someone wanting to actually write code for / port something to the SoC) or an "SDK" containing a bunch of low quality vendor code for the peripherals. I'd love to see a RISC-V SoC (not just a dinky little MCU) that has real / complete documentation. So far I have yet to find any for any of the various RISC-V based SBCs that have shipped.

yuumei 3y ago
Agreed, the best I have found so far is the SiFive Unmatched: https://www.sifive.com/boards/hifive-unmatched https://www.sifive.com/boards/hifive-unmatched which is a full mini-itx motherboard. It's not a SoC though. As far as I can see, the only thing that isn't documented is the DDR startup/training code, which is a binary blob in u-boot. There are a few registers that are undocumented which need to be set to start up but I think the rest is well documented.
- swetland 3y ago
  SiFive has pretty good documentation for their cores and chips -- they are more PC/Server class (some lowspeed peripherals plus PCIE and Ethernet) than SoC style. The databook does not have register level docs for PCIE and Ethernet but both look like off-the-shelf IP (hopefully documented somewhere -- I haven't investigated) but otherwise seems pretty thorough. https://www.sifive.com/documentation https://www.sifive.com/documentation In addition to a documented RV64 SoC, it'd be cool to see some RV32 MCUs that are a little beefier -- more competitive with the mid-range Cortex M4 and M7 stuff (more peripherals, more SRAM, etc) -- instead of the existing stuff that looks similar to very tiny M0/M3 devices.
kramerger 3y ago
This is a Wujian 600 from Alibaba (!). To my knowledge there is currently no publicly available documentation from the chip manufacturer. Was the idea of an open ISA leading to an open SoC was just wishful thinking?
- MisterTea 3y ago
  The link they liisted to the SoC is also broken: https://t-head.cn/TBD https://t-head.cn/TBD
- pclmulqdq 3y ago
  Not entirely, but the process is very slow. RISC-V (and SiFive) caught a moment where it could be used is a way to squeeze ARM on pricing. It doesn't really meaningfully create openness on the interesting parts of the stack (core architecture, SoC architecture, etc.) on its own. In that sense, the hype is overblown. It does _enable_ open-source cores to some degree, but that's it, someone has to take the leap to make a production-ready one. A few companies are trying, but an open-source SoC is even further down the road.
  - brucehoult 3y ago
    The source RTL for the roughly Arm A72-equivalent cores used in this were open-sourced several years ago. https://github.com/T-head-Semi/openc910 https://github.com/T-head-Semi/openc910 The same cores are used in the 64 core SG2042 workstation/server SoC.
- panick21_ 3y ago
  Open ISA is necessary but not sufficent. One step on a long journey.
  - kramerger 3y ago
    That is my point exactly. RISC-V was sold to us as the fully open CPU ecosystem but all it offered was an open design and some reference implementation in Chisel. That is not much different from MIPS which opensourced some CPUs 10-15 years ago. A lot more is needed for a fully open RISC-V computer.
    - panick21_ 3y ago
      Nobody sold RISC-V as a fully open CPU or SOC ecosystem. It simply allows for open source implementations to exists. > but all it offered was an open design and some reference implementation in Chisel You are confused between what RISC-V the foundation and what different people in the ecosystem do. RISC-V was started by Berkley and then they created a foundation. There are NO REFERENCE Implementation! Not in Chisel or anything else. Chisel is simply what Berkley used for some of their initial work. And it has largely worked. There are lots of high quality open CPUs. This was certainty not the case in the past: - https://www.openhwgroup.org/ https://www.openhwgroup.org/ - https://www.chipsalliance.org/ https://www.chipsalliance.org/ - https://opentitan.org/ https://opentitan.org/ There are many more. > That is not much different from MIPS which opensourced some CPUs 10-15 years ago. Its very different because you were not allowed to use those MIPS chips or built products with it. The only one that was as open was SPARC 32-bit. What we don't have is cheap mass produced SoC that are well documented. But that a general problem of the industry not just RISC-V.
MisterTea 3y ago
In addition to all that, is the GPU documented? Clicking "Request technical specs" on the Imagination website brings me to a page asking me for my business name, business email, business...
- 2Gkashmiri 3y ago
  Haha. Last time I wanted rs-232 specs of a solar inverter, took me months to contact them and after some persuasion, a guy emailed me an NDA I had to physically print, sign, scan and send them back before they gave me a copy. Obviously I was feeling funny so I signed Johnathan doe and they send me the file. Turns out, that file was readily available online in forums because others had done the same thing. So much for NDA. Sigh
  - MisterTea 3y ago
    I was looking at an import inverter that advertised CAN and rs485 support both on the website and in the manual's specs section with zero further mention. I emailed the vendor and the manufacturer at least 4 times requesting documentation with zero response. Seems to be status quo for cheap import junk. Meanwhile outback power systems offers protocol documentation in the form of manuals freely downloadable. Incredible stupidity.
    - 2Gkashmiri 3y ago
      on the contrary, in my case it was phocos.com which seems to be germany based and sells in many countries so this isn't just your rando junk but they still insist on stupid stuff
- imtringued 3y ago
  Imagination is trying to opensource their GPU drivers.
  - snvzz 3y ago
    To be more exact, they've contracted the services of a third party company to write a new mesa3d driver. Their proprietary driver will stay closed, but hopefully they'll be able to deprecate it at some point.
0xTJ 3y ago
That's my biggest problem with personally enjoying RISC-V. I'd love to play with an application-class RISC-V processor, writing an OS for it and the like, but I'm waiting on a chip that's publicly well-documented in English.
- apricot 3y ago
  If I had to wait for documentation in my native language, I would never work on any modern chips, period.
- snvzz 3y ago
  The more mature VisionFive 2 and its SoC, JH7110, have some documentation[0]. I find the most useful there is the JH7110 TRM specifically. There's links to a bunch more over here[1]. 0. https://doc-en.rvspace.org/ https://doc-en.rvspace.org/ 1. https://forum.rvspace.org/t/visionfive-2-faq-quick-links/1376 https://forum.rvspace.org/t/visionfive-2-faq-quick-links/137...
snvzz 3y ago
The more mature VisionFive 2 and its SoC, JH7110, have some documentation[0]. I find the most useful there is the JH7110 TRM specifically. There's links to a bunch more over here[1]. 0. https://doc-en.rvspace.org/ https://doc-en.rvspace.org/ 1. https://forum.rvspace.org/t/visionfive-2-faq-quick-links/1376 https://forum.rvspace.org/t/visionfive-2-faq-quick-links/137...

yuumei 3y ago

Agreed, the best I have found so far is the SiFive Unmatched: https://www.sifive.com/boards/hifive-unmatched https://www.sifive.com/boards/hifive-unmatched which is a full mini-itx motherboard. It's not a SoC though. As far as I can see, the only thing that isn't documented is the DDR startup/training code, which is a binary blob in u-boot. There are a few registers that are undocumented which need to be set to start up but I think the rest is well documented.

swetland 3y ago
SiFive has pretty good documentation for their cores and chips -- they are more PC/Server class (some lowspeed peripherals plus PCIE and Ethernet) than SoC style. The databook does not have register level docs for PCIE and Ethernet but both look like off-the-shelf IP (hopefully documented somewhere -- I haven't investigated) but otherwise seems pretty thorough. https://www.sifive.com/documentation https://www.sifive.com/documentation In addition to a documented RV64 SoC, it'd be cool to see some RV32 MCUs that are a little beefier -- more competitive with the mid-range Cortex M4 and M7 stuff (more peripherals, more SRAM, etc) -- instead of the existing stuff that looks similar to very tiny M0/M3 devices.

kramerger 3y ago

This is a Wujian 600 from Alibaba (!). To my knowledge there is currently no publicly available documentation from the chip manufacturer. Was the idea of an open ISA leading to an open SoC was just wishful thinking?

MisterTea 3y ago
The link they liisted to the SoC is also broken: https://t-head.cn/TBD https://t-head.cn/TBD
pclmulqdq 3y ago
Not entirely, but the process is very slow. RISC-V (and SiFive) caught a moment where it could be used is a way to squeeze ARM on pricing. It doesn't really meaningfully create openness on the interesting parts of the stack (core architecture, SoC architecture, etc.) on its own. In that sense, the hype is overblown. It does _enable_ open-source cores to some degree, but that's it, someone has to take the leap to make a production-ready one. A few companies are trying, but an open-source SoC is even further down the road.
- brucehoult 3y ago
  The source RTL for the roughly Arm A72-equivalent cores used in this were open-sourced several years ago. https://github.com/T-head-Semi/openc910 https://github.com/T-head-Semi/openc910 The same cores are used in the 64 core SG2042 workstation/server SoC.
panick21_ 3y ago
Open ISA is necessary but not sufficent. One step on a long journey.
- kramerger 3y ago
  That is my point exactly. RISC-V was sold to us as the fully open CPU ecosystem but all it offered was an open design and some reference implementation in Chisel. That is not much different from MIPS which opensourced some CPUs 10-15 years ago. A lot more is needed for a fully open RISC-V computer.
  - panick21_ 3y ago
    Nobody sold RISC-V as a fully open CPU or SOC ecosystem. It simply allows for open source implementations to exists. > but all it offered was an open design and some reference implementation in Chisel You are confused between what RISC-V the foundation and what different people in the ecosystem do. RISC-V was started by Berkley and then they created a foundation. There are NO REFERENCE Implementation! Not in Chisel or anything else. Chisel is simply what Berkley used for some of their initial work. And it has largely worked. There are lots of high quality open CPUs. This was certainty not the case in the past: - https://www.openhwgroup.org/ https://www.openhwgroup.org/ - https://www.chipsalliance.org/ https://www.chipsalliance.org/ - https://opentitan.org/ https://opentitan.org/ There are many more. > That is not much different from MIPS which opensourced some CPUs 10-15 years ago. Its very different because you were not allowed to use those MIPS chips or built products with it. The only one that was as open was SPARC 32-bit. What we don't have is cheap mass produced SoC that are well documented. But that a general problem of the industry not just RISC-V.

MisterTea 3y ago

In addition to all that, is the GPU documented? Clicking "Request technical specs" on the Imagination website brings me to a page asking me for my business name, business email, business...

2Gkashmiri 3y ago
Haha. Last time I wanted rs-232 specs of a solar inverter, took me months to contact them and after some persuasion, a guy emailed me an NDA I had to physically print, sign, scan and send them back before they gave me a copy. Obviously I was feeling funny so I signed Johnathan doe and they send me the file. Turns out, that file was readily available online in forums because others had done the same thing. So much for NDA. Sigh
- MisterTea 3y ago
  I was looking at an import inverter that advertised CAN and rs485 support both on the website and in the manual's specs section with zero further mention. I emailed the vendor and the manufacturer at least 4 times requesting documentation with zero response. Seems to be status quo for cheap import junk. Meanwhile outback power systems offers protocol documentation in the form of manuals freely downloadable. Incredible stupidity.
  - 2Gkashmiri 3y ago
    on the contrary, in my case it was phocos.com which seems to be germany based and sells in many countries so this isn't just your rando junk but they still insist on stupid stuff
imtringued 3y ago
Imagination is trying to opensource their GPU drivers.
- snvzz 3y ago
  To be more exact, they've contracted the services of a third party company to write a new mesa3d driver. Their proprietary driver will stay closed, but hopefully they'll be able to deprecate it at some point.

0xTJ 3y ago

That's my biggest problem with personally enjoying RISC-V. I'd love to play with an application-class RISC-V processor, writing an OS for it and the like, but I'm waiting on a chip that's publicly well-documented in English.

apricot 3y ago
If I had to wait for documentation in my native language, I would never work on any modern chips, period.
snvzz 3y ago
The more mature VisionFive 2 and its SoC, JH7110, have some documentation[0]. I find the most useful there is the JH7110 TRM specifically. There's links to a bunch more over here[1]. 0. https://doc-en.rvspace.org/ https://doc-en.rvspace.org/ 1. https://forum.rvspace.org/t/visionfive-2-faq-quick-links/1376 https://forum.rvspace.org/t/visionfive-2-faq-quick-links/137...

snvzz 3y ago

The more mature VisionFive 2 and its SoC, JH7110, have some documentation[0]. I find the most useful there is the JH7110 TRM specifically. There's links to a bunch more over here[1]. 0. https://doc-en.rvspace.org/ https://doc-en.rvspace.org/ 1. https://forum.rvspace.org/t/visionfive-2-faq-quick-links/1376 https://forum.rvspace.org/t/visionfive-2-faq-quick-links/137...