riscv-non-isa/riscv-ap-tee

CoVE-IO FID namespace

sameo opened this issue · 3 comments

sameo commented

The CoVE-IO specification extends the CoVE ABI for supporting device direct assignment into TVMs.

The CoVE-IO ABI extensions require their own SBI FIDs and are currently left TBD in the spec. I propose that we assign a specific FID range for CoVE-IO, so that the CoVE and CoVE-IO FIDs can be formally defined without overlapping or interleaving.

Since FIDs can fill an entire register (a6), one possibility would be to reserve the top half COVG and COVH EID spaces for CoVE extensions. CoVE-IO could e.g take 6 bits from there and use them as needed.

@rsahita @jyao1 WDYT?

jyao1 commented

Yes, I like this proposal to separate role and responsibility.

rsahita commented

sounds good - we should also make sure there are some reserved portions for other future extensions.

sameo commented

sounds good - we should also make sure there are some reserved portions for other future extensions.

Yep.
I'll send a PR for this.