What does HackerNews think of openc910?

OpenXuantie - OpenC910 Core

Language: Verilog

Russia is not that great an example because they don't actually manufacture anything at all that we'd miss, and we can quickly get gas and oil from elsewhere (and have done so).

The Chinese and US economies are far more inter-dependent and the Chinese understand that war is unthinkable -- are are very annoyed at Russia.

The Western response to Ukraine has also put China off the notion that they could quietly take Taiwan without anyone making a fuss.

But this is very far from RISC-V.

China has long since (5+ years) taken everything from RISC-V initially done in the West that there is to take. The ISA specification itself, gcc and llvm and Linux and things like that. It is far too late to change that. They have local git clones.

At present China is contributing more to RISC-V than anyone else. For example they are doing almost all work on Android and all the parts that go into that, including things such as the Chromium browser.

All their improvements go into public repositories that the rest of the world can access.

Companies such as WCH and THead and StarFive are also at the forefront of RISC-V cores and chips that normal people can actually buy. WCH's $0.10 microcontrollers are really great (as are their $0.50 and $1.00 chips). THead's C910 core is not only in the highest performance RISC-V SoCs (TH1520, SG2042) and boards you can buy right now, it is also open source (https://github.com/T-head-Semi/openc910) with a permissive license so anyone can audit it, or take the design as a starting point. StarFive's "Dubhe" core will probably be available on SBCs in the next 6-12 months, and will be similar to Rockchip's RK3588, currently the fastest ARM chip available on SBCs.

Here is the source code* for the CPU:

https://github.com/T-head-Semi/openc910

* AFAIK they didn't opensource the pre ratification vector extension implementation they ship with the taped out chip.

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

The same cores are used in the 64 core SG2042 workstation/server SoC.

>It's so hard to imagine so many years & a microarchitecture remaining so unchanging.

It's a shame, because it was the best design from ARM; they're now focusing on Cortex-A7x and Cortex-X, which aren't anywhere as power efficient[0].

Meanwhile, their revised Cortex-A57 has been surpassed in performance/power/area by several RISC-V microarchitectures, such as SiFive's U74[1], used in the VisionFive2 and Star64, or even the open source XuanTie C910[2][3].

0. https://youtu.be/s0ukXDnWlTY?t=790

1. https://www.sifive.com/cores/u74

2. https://xrvm.com/cpu-details?id=4056743610438262784

3. https://github.com/T-head-Semi/openc910

It's been available on the RVB ICE for 18 months:

https://www.aliexpress.us/item/3256803209663707.html

It's also been open source (without the vector unit) for a similar amount of time:

https://github.com/T-head-Semi/openc910

This board certainly marks a big improvement in price/performance for C910 boards, and a significant performance improvement over the VisionFive 2 also, at an only slightly higher price.

No M.2 slot seems to be the only disadvantage. The TH1520 SoC apparently doesn't have PCIe at all. The SG2042 SoC has 64 C910 cores and 32 lanes of PCIe gen 4.

It looks like so far there are two Linux usable Risc-V cores: those from Alibaba's c910[0], and those from sifive (like this one). There is also OpenXiangShan[1] which is an academic project which has seen real tape out but so far no product that I'm aware of. I believe XiangShan is somewhat based on Berkley's BOOM[2], someone who knows can correct me on this.

My hope is that in the long run it makes sense for cloud companies to fund open source CPU development. They already fund closed source development by paying Intel, AMD, and now ARM (some of which is in house like Graviton). It shouldn't be so expensive throw a few million at this. Google and Amazon already have some in house talent. I don't think these cloud companies really want to be in the business of (closed source) hardware development. At the very least, they can put pressure on the existing CPU companies: what are they going to do - lose out on their largest market? The cloud companies are in control here.

[0]https://github.com/T-head-Semi/openc910 [1]https://github.com/OpenXiangShan/XiangShan [2]https://github.com/riscv-boom

The spec is free, and a lot of cores are free as well. Here's the HDL for AliBaba's cores they've been developing this against: https://github.com/T-head-Semi/openc910

There are also non-free RISC-V cores, but they essentially have to continuously make the argument for their existence against the free cores that are available (support, verification resources, just being better designs in the short term, already being hardened for proprietary process nodes, etc.)

AliBaba has been open sourcing their designs though. AFAIK, this work is mainly against their XuanTie C910 cores that have the source published here: https://github.com/T-head-Semi/openc910