riscv-profiles VS VisionFive2

Ssstrict is supposed to address the undefined behaviour problem, or at least it'll make undefined instructions actually trap.

https://github.com/riscv/riscv-profiles/blob/main/rva23-prof...

>there are a lot of incompatible ISA implementations of RISC-V

This is common FUD.

In reality, most chips in the market, including all known application processors, follow the RVA profile[0] spec.

So do Linux distributions.

0. https://github.com/riscv/riscv-profiles/releases

The bit manipulation [0] extension has been ratified for a while now and is part of the RVA22 application extension profile [1].

You can already buy SOCs that support it, e.g. vision five 2 and star64.

Interestingly the risc-v vector has it's own popcount instructions for vector registers/register masks. This is needed, because the scalable architecture doesn't guarantee that a vector mask can fit into a 64 bit register, so vector masks are stored in a single LMUL=1 register. This works really well, because with LMUL=8 and SEW=8 you get 100% utilization of the single LMUL=1 vector register.

Another interesting thing is that the vector crypto extension will likely introduce a element wise popcount instruction.

[0] https://github.com/riscv/riscv-bitmanip/releases/download/1....

[1] https://github.com/riscv/riscv-profiles/blob/main/profiles.a...

That's why we have RISC-V profiles.

Yeah more or less. They now have RISC-V Application Profiles which are basically minimum requirements for "application processors" - essentially devices like phones where you might want to distribute binary apps.

The Profiles spec which includes RVA22 was finally ratified[0] last week.

0. https://github.com/riscv/riscv-profiles/releases/tag/v1.0

Context: RISC-V profiles spec got ratified last week.

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.a...

The 22 indicates the year.

Ah, you're right: https://github.com/riscv/riscv-profiles/blob/main/profiles.a...

That's good to see. (Boy, it's really hard to find info about RISC-V profiles on Google. It just seems to ignore all the letters and numbers.)

booted from your SD wget https://github.com/starfive-tech/VisionFive2/releases/download/VF2_v2.11.5/u-boot-spl.bin.normal.out wget https://github.com/starfive-tech/VisionFive2/releases/download/VF2_v2.11.5/visionfive2_fw_payload.img flashcp -Av u-boot-spl.bin.normal.out /dev/mtd0 flashcp -Av visionfive2_fw_payload.img /dev/mtd1

Much of required support things for RISC-V SBC's across the board are incomplete/missing in mainline Linux device tree. VF2 is better than most random ARM SBC boards though, and there are efforts to upstream/mainline. RISC-V SBCs are just too new as a product category for mainline support to be possible quite yet. StarFive are open about this and the checklists/efforts going on: https://github.com/starfive-tech/linux/tree/visionfive and https://github.com/starfive-tech/VisionFive2

You can use this image to update by connecting through ssh: https://github.com/starfive-tech/VisionFive2/releases/download/VF2_v2.5.0/sdcard.img

FWIW, there was new firmware released on Jan. 20: https://github.com/starfive-tech/VisionFive2/releases/tag/VF2_v2.8.0

Or you can try to build it yourself: https://github.com/starfive-tech/VisionFive2

I presume you've already seen issue 5 regarding the GPU driver files.