SBI spec: return code for non-available extension

[Anup Patel]

On Sat, Mar 6, 2021 at 12:33 PM Heinrich Schuchardt <xypron.glpk at gmx.de> wrote:
>
> Software may by fault invoke an extension which is not available.
>
> OpenSBI actually returns SBI_ERR_NOT_SUPPORTED from sbi_ecall_handler()
> in this case.
>
> This is a reasonable choice but I could not find any basis in the SBI
> specification. The handling of an ecall for an unsupported EID is not
> described.

The SBI_ERR_NOT_SUPPORTED error code is the default error code
any unsupported function. This should be clearly mentioned in the
SBI base extension if it is not already mentioned.

>
> I think this gap should be closed in the spec.

Totally agree.

Please go ahead and send a patch (or Github PR) for SBI spec.
(Refer, https://github.com/riscv/riscv-sbi-doc)

Our mailing for SBI spec is the UnixPlatformSpec mailing list but
you need to join RiSC-V International as an individual to join the
mailing list (https://lists.riscv.org/g/tech-unixplatformspec).
(Note: AFAIK individual membership is free for RISC-V international).

Regards,
Anup

>
> Best regards
>
> Heinrich
>
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