RFR: 8324304: RISC-V: add hw probe flags [v2]

[Hamlin Li]

On Fri, 26 Jan 2024 09:42:54 GMT, Fei Yang <fyang at openjdk.org> wrote:

>> I'm not sure, as these vm options (UseZic64b, UseZicbom, UseZicbop and UseZihintpause) are not `enable`d in RiscvHwprobe::add_features_from_query_result(), so I think they are not enabled automatically even if the hw supports these features, unless a vendor want to enable them.
>> 
>> So, I think it's good to keep auto-enablement of Zicboz/Ztso/Zacas in vm_version_riscv.hpp, and remove the enable code of these options in RiscvHwprobe::add_features_from_query_result() in this patch?
>
>> I'm not sure, as these vm options (UseZic64b, UseZicbom, UseZicbop and UseZihintpause) are not `enable`d in RiscvHwprobe::add_features_from_query_result(), so I think they are not enabled automatically even if the hw supports these features, unless a vendor want to enable them.
> 
> Sorry, I missed that before. I think you are right.
> 
>> So, I think it's good to keep auto-enablement of Zicboz/Ztso/Zacas in vm_version_riscv.hpp, and remove the enable code of these options in RiscvHwprobe::add_features_from_query_result() in this patch?
> 
> Yeah, that will be more consistent.

Thanks @RealFYang @robehn for your reviewing.

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PR Comment: https://git.openjdk.org/jdk/pull/17519#issuecomment-1914270694