CDC Waiver Policy: Mechanism

Mechanism to understand

Mechanism for CDC Waiver Policy focuses on open critical waivers, stale waiver age, waiver quality score. The goal is to convert issue observations into mechanism-backed closure decisions.

Waivers are controlled risk acceptances and must include mechanism justification, containment evidence, and ownership for periodic revalidation. Treat each warning as a behavior contract violation candidate, then prove whether it is real risk or tool noise.

• Classify crossing type and data criticality.

• State source/destination clock or reset relationship.

• Identify when protocol semantics dominate topology choice.

System flow

CDC/RDC SIGNOFF FLOW — CDC Waiver Policy

crossing inventory + reset map
          |
          v
crossing classification (level/pulse/bus/reset)
          |
          v
structure + protocol + reset checks
          |
          v
critical issues + waiver review
          |
          v
fix / validate / regress / signoff

Waiver risk rubric

waiver request
   -> mechanism explanation
   -> containment evidence
   -> silicon-risk rating
   -> owner + expiry
   -> approve / reject

Layer responsibilities

CDC/RDC OWNERSHIP LAYERS — CDC Waiver Policy

layer                 owns                            common failure
------------------    -----------------------------   -----------------------------
design intent         crossing architecture           wrong topology selected
protocol semantics    req/ack, fifo, ordering        liveness/deadlock bugs
reset behavior        assert/deassert sequencing      boot instability
analysis setup        tool rules + waivers            false confidence
signoff governance    risk acceptance + dashboard     stale critical waivers

CDC/RDC deep dive

Signoff is an evidence governance problem across teams.

Concept diagram

CDC SIGNOFF LOOP

analysis -> triage -> fix/waive -> review gate -> dashboard

Metric graph

CRITICAL OPEN COUNT

week1 34
week2 22
week3 10
week4 0

Reports and artifacts

• critical by owner

• waiver quality

• review gate status

• closure trend

Mini case study

Pass rates improved while critical waivers aged out of policy; dashboard exposed hidden risk.

Debug branches

• Separate quality from quantity metrics

• enforce waiver expiry

• run gate checklists consistently

Senior review question

Ask: what evidence proves this risk is closed for silicon, not just tool-clean?

Key takeaways

• State crossing class, assumptions, and owner with every issue.

• Run structural and dynamic regressions after each fix.

Common pitfalls

• Treating all warnings as equivalent risk.

• Waiving issues without containment evidence.

• Skipping reset and reconvergence stress after CDC fixes.

Mechanism deep dive

Waivers are controlled risk acceptances and must include mechanism justification, containment evidence, and ownership for periodic revalidation.