Scenario: Metastability Bug: Step-by-Step Walkthrough

Step-by-step analysis walkthrough

Use this sequence when owning Scenario: Metastability Bug in a signoff review.

1. Inspect warning class and severity.

2. Trace crossing endpoints and domains.

3. Check protocol/reset assumptions against spec.

4. Review synchronizer or FIFO implementation detail.

5. Run focused assertion or formal check.

6. Draft fix options with risk and schedule impact.

7. Execute regression and publish closure memo.

Artifacts to collect

• failure report, crossing path analysis, fix validation plan

• crossing inventory

• waiver board notes

• regression report

Decision memo template

CDC/RDC DECISION MEMO — Scenario: Metastability Bug
risk class:
mechanism:
evidence:
fix/waiver:
owners: candidate, CDC owner, DV lead

Reference visuals

Metastability escape anatomy

rare field failure
  -> thermal/voltage stress
  -> settle window collapse
  -> bad sample observed

Scenario debrief

Score each response on mechanism clarity, evidence quality, and signoff decision discipline.

INTERVIEW FLOW

classify -> explain mechanism -> propose fix -> state regression

PRACTICE SCORE

session1 62%
session2 78%
session3 89%

Debrief prompts

1. Which crossing class or reset dependency failed first?

2. What evidence changed your decision?

3. Fix, waive, or escalate and why?

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.