opentitan
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lowRISC
[rv_plic] V2(S) Signoff
Description
Ensure V2(S) signoff criteria are still maintained (this is not a focus area block).
This issue is WIP.
Commits since Earlgrey-ES tapeout
$ git rev-parse --short HEAD
c5faa9b8b3
$ git log Earlgrey-M2.5.2-RC0..HEAD --oneline hw/ip_templates/rv_plic
4a9a881d44 [topgen] Pass topname key/value pair to ipgen de31bdf1c2 [reggen] Remove the devmode input 620bd3401f [rv_plic,sival] List rv_plic features in its hjson file eee74c3d2e [ip_templates,hjson] Remove clutter 7688e714e8 [reggen] Add initial support for version and cip_id hjson fields fbd888eea8 Revert "[reggen] Add CIP_IDs and bump all major versions" 0ba10b3cd3 [reggen] Add CIP_IDs and bump all major versions
Issues closed since the Earlgrey-ES tapeout
- #14839
- This was a review task to make sure there are no alignments needed in order to be compliant with the RISC-V PLIC 1.0.0 spec
- #17412
- stale SVAs in the testplan, will be removed in #21655
Currently open issues
- #21414
- sival issue
- #17307
- general doc improvement, not needed for D2S.
- #15584
- this describes behavior that was observed in top-level tests: the interrupt signal propagation delays are dependent on the peripheral clock frequency. I don't think we should and will be able to change anything for PROD here, since this behavior is inherent to the chosen implementation.
- #12848
- this is a top-level doc improvement, not needed for D2S.
- #8440
- this IP is already IPgen'd
- #3421
- this is a future improvement at the system level and no change is needed in rv_plic
- #270
- very old issue about adding support for different multireg structures with nested register arrays. this is not within scope for PROD.
Coverage report from
| name | pass_rate | stimuli_cov | coi_cov | prove_cov |
|---|---|---|---|---|
| rv_plic_fpv | 100.00 % | 71.23 % | 93.31 % | 69.94 % |
Summary
There have been no hardware changes since the ES tapeout, and no critical bugs have been found. The recommendation is hence to leave this IP at the V2 stage claimed in its Hjson file: https://github.com/lowRISC/opentitan/blob/c5faa9b8b368c89fcef131440ba906f62f9595d5/hw/ip_templates/rv_plic/data/rv_plic.hjson.tpl#L22-L30
I'm convinced!
About the coverage report, I believe that verification of rv_plic is FPV-based (e.g. looking at hw/ip_templates/rv_plic/doc/dv/README.md). So I'm not sure we're going to have any way to make a "simulation-based coverage report" in the way we'd do for most blocks.
There is a way to extract coverage from FPV, and I was going to rerun after I looked at those missing assertions that are mentioned in the issues.
Reran FPV and all assertions pass. COI coverage is above 75% which we require for this milestone. Given that this block is heavily used in top-level tests as well, and there have been no RTL changes nor issues reported since the ES tapeout, I think we can sign this block off.