RFR: 8309258: RISC-V: Add riscv_hwprobe syscall [v2]

[Robbin Ehn]

On Wed, 14 Jun 2023 06:39:25 GMT, Thomas Stuefe <stuefe at openjdk.org> wrote:

> I just got curious. Small nits and questions.
> 
> It seems odd to add individual vendor capabilities, but since its democratic and every vendor can add theirs, I think this is fine.

Hey! Thanks for having a look!

If you check x86 we already have things like:

if (is_intel()) { // Intel cpus specific settings
    if (is_knights_family()) {
      _features &= ~CPU_VZEROUPPER;
      _features &= ~CPU_AVX512BW;


In the vendor specific path you make different features available per march/mimplid.

So I hope this makes a bit more sense with that in mind.

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PR Comment: https://git.openjdk.org/jdk/pull/14445#issuecomment-1590617865