CDC Waiver Policy: Software / Programmer View

RTL / implementation view

Design teams need evidence-ready crossing documentation from day one.

What designers feel

• Intermittent sync failure

• mode-dependent startup hangs

RTL structure impact

• state machine handshake discipline

• reset release assumptions

• cross-domain data packaging

Synthesis interaction

• retiming can invalidate implicit assumptions

• lint clean does not imply CDC-safe

RTL-side mitigations

• explicit synchronizer wrappers

• protocol assertions

• reset sequence tests

RTL VIEW — CDC Waiver Policy
// ensure crossing intent and protocol assumptions are explicit in module contract

Implementation layers touched

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.

Principal CDC/RDC review addendum

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

Metric: open critical waivers, stale waiver age, waiver quality score