LPV Regression: Software and Programmer View

Software and programmer view

Debug velocity depends on evidence quality, not waveform volume.

What teams feel

• mode-entry regressions that are hard to reproduce

• inconsistent behavior across simulators or config profiles

• late triage loops due to weak failure classification

API and integration impact

• PMU and firmware handshake contract clarity

• power-mode API assumptions and timing envelopes

• testbench sequencing ownership and checker placement

Tooling and compile-time implications

• tool power-aware semantics and elaboration assumptions

• assertion noise versus actionable signal quality

• coverage aggregation consistency across runs

Mitigations

• standardize LPV run metadata and transition sequence capture

• gate key regressions on deterministic replay checks

• enforce boundary ownership in review templates

SOFTWARE VIEW - LPV Regression
// prove phase ordering and boundary controls before broad waivers

Low-power verification deep dive

Signoff confidence comes from triage discipline, reproducible proof, and explicit residual-risk decisions.

Concept diagram

LPV SIGNOFF LADDER

reproduce -> classify -> isolate boundary -> bounded fix -> replay -> signoff decision

Metric graph

SIGNOFF CONFIDENCE

open ambiguous failures  ██████
reproducible closures    ███████
residual-risk unknowns   ███

Metrics and artifacts to collect

• X-prop triage classification report

• bug root-cause closure packet

• regression stability and recurrence trend

• signoff checklist completion matrix

Mini case study

A signoff block cleared after the team replaced broad waivers with boundary-specific evidence and replay criteria.

Debug branches

• Classify X behavior before broad waiving.

• Capture one definitive artifact packet per closure claim.

• Define residual risk and rollback path at signoff.

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.

Principal LPV review addendum

LPV Regression should be reviewed as a transition integrity system, not just isolated checks.

Use illegal transition count, corruption incidence, and reproducibility of low-power regressions across fixed seeds as alarm and LPV evidence packet: transition timeline, assertion outcomes, and before-after replay summary as proof.

LPV debug and signoff require disciplined triage: classify X behavior, isolate root cause, and close with reproducible evidence. Closure quality comes from reproducible evidence and explicit owners.