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I purchased a DE10-nano last year with the plan to try some FPGA RISC-V based development... but got lost in the number of extensions and versions of RISC-V kic

I purchased a DE10-nano last year with the plan to try some FPGA RISC-V based development... but got lost in the number of extensions and versions of RISC-V kicking around. Has anyone tried this? I'd also be interested how it compares performance wise to the above, and Pi4, see if it worth the effort. Anyway at least it got some good use with MiSTer :) I kinda hope Raspberry adopts RISC-V on their next SBC, but hopefully with more open hardware.

jburgess777 4y ago
The repo below has support for building a 32bit RISC-V CPU for de10nano. It also includes information about booting Linux. https://github.com/litex-hub/linux-on-litex-vexriscv https://github.com/litex-hub/linux-on-litex-vexriscv The CPU will likely have a clock speed around 100Mhz, far slower than the 1.5Ghz 64bit cores on the VisionFive 2 or Pi4. The FPGA might still be useful if you want to customize the CPU or integrate other custom hardware.
- whitehexagon 4y ago
  Open source tool chain and open source cores, wow, nice progress since I last looked into this.
IshKebab 4y ago
Yeah unfortunately there isn't really a great place that lists all the extensions with links and ratification status. But anyway there is a sort of standard set of extensions that "application processors" (I guess CPUs that want to run precompiled code) should support: https://github.com/riscv/riscv-profiles/blob/main/profiles.adoc#rva22u64-profile https://github.com/riscv/riscv-profiles/blob/main/profiles.a... The 22 indicates the year.
- whitehexagon 4y ago
  thanks, so for something like the reviewed board above, how would RV64GC map into one of those profiles, or set of supported instructions?
  - brucehoult 4y ago
    RV64GC expands into RV64I + M + A + F + D + C. The CPU in this board also has the Zba and Zbb extensions (which together with a couple of others make up what was originally envisioned as the "B" extension, but it was decided to split it up).
- snvzz 4y ago
  >Yeah unfortunately there isn't really a great place that lists all the extensions with links and ratification status. RISC-V's wiki specification status page[0] is about as good as it gets. 0. https://wiki.riscv.org/display/HOME/Specification+Status https://wiki.riscv.org/display/HOME/Specification+Status

jburgess777 4y ago

The repo below has support for building a 32bit RISC-V CPU for de10nano. It also includes information about booting Linux. https://github.com/litex-hub/linux-on-litex-vexriscv https://github.com/litex-hub/linux-on-litex-vexriscv The CPU will likely have a clock speed around 100Mhz, far slower than the 1.5Ghz 64bit cores on the VisionFive 2 or Pi4. The FPGA might still be useful if you want to customize the CPU or integrate other custom hardware.

whitehexagon 4y ago
Open source tool chain and open source cores, wow, nice progress since I last looked into this.

IshKebab 4y ago

Yeah unfortunately there isn't really a great place that lists all the extensions with links and ratification status. But anyway there is a sort of standard set of extensions that "application processors" (I guess CPUs that want to run precompiled code) should support: https://github.com/riscv/riscv-profiles/blob/main/profiles.adoc#rva22u64-profile https://github.com/riscv/riscv-profiles/blob/main/profiles.a... The 22 indicates the year.

whitehexagon 4y ago
thanks, so for something like the reviewed board above, how would RV64GC map into one of those profiles, or set of supported instructions?
- brucehoult 4y ago
  RV64GC expands into RV64I + M + A + F + D + C. The CPU in this board also has the Zba and Zbb extensions (which together with a couple of others make up what was originally envisioned as the "B" extension, but it was decided to split it up).
snvzz 4y ago
>Yeah unfortunately there isn't really a great place that lists all the extensions with links and ratification status. RISC-V's wiki specification status page[0] is about as good as it gets. 0. https://wiki.riscv.org/display/HOME/Specification+Status https://wiki.riscv.org/display/HOME/Specification+Status