RFR: 8297697: RISC-V: Add support for SATP mode detection [v2]

[Feilong Jiang]

On Tue, 29 Nov 2022 07:09:50 GMT, Fei Yang <fyang at openjdk.org> wrote:

>> Feilong Jiang has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   print vm mode string instead of vm mode code
>
> src/hotspot/cpu/riscv/vm_version_riscv.cpp line 41:
> 
>> 39: 
>> 40:   // check if satp.mode is supported, currently supports up to SV48(RV64)/SV32(RV32)
>> 41:   if (get_satp_mode() > RISCV64_ONLY(VM_SV48) RISCV32_ONLY(VM_SV32)) {
> 
> I am not sure whether it makes sense to consider SV32 here. We only support RV32 Zero for now and haven't seen a simillar issue for it yet.

As RISC-V32 only has Zero support, it's safe to remove SV32. We can add it back when RV32 backend is ready.

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PR: https://git.openjdk.org/jdk/pull/11388