Is sbi_cppc_read_hi allowed to ignore reserved/unimplemented register IDs?

[repnop]

The documentation for sbi_cppc_read_hi currently reads:

This function always returns zero in sbiret.value when supervisor mode XLEN is 64 or higher.

Does this imply no validity checking is done when called with XLEN >= 64, or should implementations still return an error on a reserved or unimplemented register ID?

[atishp04]

Yes. No validity checking is required when sbi_cppc_read_hi is called with XLEN >= 64. The additional validity checking is unnecessary because the sbi_cppc_read_hi can't provide any meaningful value when XLEN>=64 . There is no point in burdening the implementation with additional sanity checks. The invalid register would have already checked with cppc_probe call also.