Submissions of extensions to the Unpriv and Priv ICs for official Architecture Review and for Opcode/CSR Assignment Review (and official allocation) should be emailed to  A row for your submission must also be added to the bottom of the Arch Review Status table below, and please fill in all fields except for the Status/ETA field. 

Once arch review results have been provided back to the TG, spec changes corresponding to requested changes/corrections/etc. do not need to be re-reviewed.  But any other substantive post-review architectural changes must be presented back to the Arch Review committee (using the above email) for approval.  Ideally there should not be any such changes, but a simple email summarizing the what and why of any changes is sufficient.

Arch Review Status Table

Extension NameIncluded Extensions
(e.g. Zkr, Zbk[bcx], ...)
Submitting TGContact(s) name and email
(Chair, Vice-chair, Architect, Editor, etc.)
StatusStatus Dateprojected completion dateComments/blockers/next steps
Pointer MaskingZjpmJ

Martin Maas (
Adam Zabrocki (

Submitted23 July 2021Q4 '21Initial full review completed.  Review of eventual updated spec to be done once submitted.
Packed SIMDZpsfoperand, Zprvsfextra, Zpn, Zbp[??]PChuanhua Chang ( June 2021Started, tbd finish

Full review

psABIpsABISoftwareKito Cheng ( April 2022Q2 '22Full review
Wait on Reservation SetZawrsFast-trackVedvyas Shanbhogue ( May 2022Q2 '22Full review

In addition to the extension spec, please submit information about the PoCs and about utility/efficiency (although we don't need all the gory detail - a paragraph or so for each can be fine).  For items considered to not be consequential, a sentence or so explaining why should suffice.

  • Consistency with the RISC-V architecture and philosophy
  • Documentation clarity and completeness
    • Including proper distinction between normative and non-normative text
  • Motivation and rationale for the features, instructions, and CSRs
  • Utility and efficiency (relative to existing architectural features and mechanisms)
    • Is there enough value or benefit to justify the cost of implementation?
    • Is the cost in terms of area, timing, and complexity reasonable?
  • Proof of Concept (PoC)
    • Software PoC to ensure feature completeness and appropriateness for intended use cases
    • Hardware PoC to demonstrate reasonable implementability
  • Inappropriate references to protected IP (i.e. covered by patents, copyright, etc.)

If, for now, you primarily want to nail down opcode/CSR assignment and have a solid draft spec (but not a final spec ready for official Arch Review), then mention this in your email submission so we know to focus on just the opcode/CSR assignments (but in the context of the spec).

Similarly, while a spec is being developed, if there is need for a first-order spec review of certain key architectural assumptions being made (e.g. to make sure that these will ultimately be considered acceptable and appropriate), then explain this in the submission and highlight the key assumptions that we should focus on evaluating for now.

Lastly, note that Arch Review doesn't concern itself with Definition-of-done (DoD) checklist items like Spike/QEMU/Sail support, ACTs, and software support.  Waivers are a matter for Tech Chairs to approve, and review of the other DoD requirements occurs through the various IC/HC sign-offs and the overall review/approval by tech-chairs.

The email addresses for the primary reviewers are: 

Krste Asanovic <>
Andrew Waterman <>
John Hauser <>
Greg Favor <>

Approved extensions:


Zba, Zbb, Zbc, Zbs  (BitManip)


Zfinx, Zdinx, Zhinx, Zhinxmin

Zbkb, Zbkc, Zbkx, Zknd, Zkne, Zknh, Zksed, Zksh, Zkr, Zkn, Zks  (Scalar Crypto)

V (and several Zve* extensions)

Zicbom, Zicbop, Zicboz

Priv 1.12



Svnapot, Svpbmt, Svinval





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