[davidlt]

Zba, Zbb, Zbc, Zbs (BitManip) have been approved by "Architecture Review" thus I assume they close to being ratified. Probably one of the first new extensions to be available for RISC-V.

Because it's not ratified the BitManip extensions are not listed in any RISC-V Profiles as supported (or required). Platforms specification is also not requiring it.

Note that the next Profiles will be for 2022, thus any extension ratified before that most likely will appear in a new profile (i.e. as supported, non-conflicting extension) in some set.

[ncmncm]

OK, so does the "RV64" checkmark on the page mean anything at all?

[rwmj]

RV64 on that page refers to the fact the instruction can be implemented (as part of the B extension) on 64 bit RISC-V. RISC-V itself has a well-defined system of base ISA + extensions as explained in section 1.3 of the user specification, available from here: https://riscv.org/technical/specifications/