Low Power Verification · All levels

Closing Low-Power Coverage for Signoff: Debug Playbook

Debug Playbook for Closing Low-Power Coverage for Signoff.

Debug playbook

Debug Playbook for Closing Low-Power Coverage for Signoff is anchored on illegal transition rate, corruption incidence, and deterministic replay quality under low-power scenarios. Convert observations into mechanism-backed and owner-bound actions.

Freeze seed, metadata, and boundary under investigation.
Locate first persistent low-power phase divergence.
Classify mechanism: setup, transition, boundary, retention, or X-prop class.
Apply one focused reproducer and one bounded fix.
Re-run determinism and broader regression matrix.

Review memo template

diagram

LPV REVIEW MEMO - Low Power Assertions & Coverage / Closing Low-Power Coverage for Signoff

1. Symptom
   - Failing metric: illegal transition rate, corruption incidence, and deterministic replay quality under low-power scenarios
   - Trigger context: <seed/mode/sequence>
   - First failing phase: <entry/off/exit/boundary>

2. Mechanism hypothesis
   - Candidate mechanism: Low-power coverage closure is a risk management exercise, not a percentage chase. Closure planning should classify uncovered bins by potential silicon impact, observability, and reproducibility, then assign directed tests, constrained-random biasing, formal obligations, or justified waivers with explicit ownership. High-confidence closure requires demonstrating repeated pass stability on critical transition scenarios, linking assertion hit data to functional bins, and proving that waived cases are unreachable or acceptable under documented product constraints. Teams that close efficiently maintain a live gap dashboard connecting each missing bin to specific UPF intent clauses, failing/absent checkers, and planned stimulus updates, while continuously tracking escaped-bug trends to validate that closure strategy is reducing real risk. Final signoff should include evidence for state and transition completeness, isolation and retention robustness, and post-wake protocol integrity under realistic concurrency.
   - Competing hypotheses: setup, transition race, boundary bug, retention drift, X-prop noise
   - Missing evidence: <trace/assertion/report>

3. Proposed action
   - Smallest reversible change: <intent/RTL/checker/flow>
   - Expected movement: <failure trend/replay stability>
   - Regression risk: compatibility, coverage, signoff delay

4. Signoff
   - Required artifact: evidence packet for Closing Low-Power Coverage for Signoff: transition timeline, assertions, and before-after replay summary
   - Required owners: LPV lead, power-intent owner, Low Power Assertions & Coverage owner
   - Final decision: ship, bounded rollout, rollback, or escalate

Low-power verification deep dive

Assertions and coverage translate LPV intent into measurable closure confidence and prioritized risk reduction.

Concept diagram

diagram

COVERAGE CLOSURE LOOP

intent risk -> assertions and checkers -> coverage evidence -> closure gaps -> targeted scenarios

Metric graph

diagram

COVERAGE MATURITY

raw hits                 ███████
actionable closure hits  █████
uncovered high-risk bins ███

Metrics and artifacts to collect

assertion failure taxonomy
mode-transition coverage heatmap
crossing risk coverage report
coverage closure readiness packet

Mini case study

Coverage closure accelerated once failures were grouped by transition risk class instead of tool report order.

Debug branches

Prioritize coverage by product-risk scenarios.
Separate actionable assertion classes from setup noise.
Use closure criteria with explicit waiver governance.

Senior review question

Ask: what exact low-power transition boundary failed first, and which artifact proves the closure claim reproducibly?

Key takeaways

Tie each LPV claim to a concrete transition boundary and one proving artifact.
Prefer minimal reversible fixes with explicit owner and rollback criteria.

Common pitfalls

Treating power-aware failures as random before boundary classification.
Waiving X-prop failures before proving impact and root cause.
Declaring closure without deterministic replay across key modes.

Debug ladder

Sequence: reproduce -> classify -> isolate boundary -> prove mechanism -> bounded fix.

Avoid mixed fixes before first-principles classification.

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