How do you approve an intentional undriven or unloaded object?
From PDVerse PnR Interview Handbook · pdVerse Mentor Guide
Short Answer
Require named-object evidence, functional reason, affected modes, owner, risk, and a rerun-stable waiver; never waive only a message count.
Technical Explanation
Treat this as a readiness check. It should produce named objects and a result that another engineer can repeat from the same handoff.
What To Check
• Warning sign: A test output is intentionally unused, but the waiver pattern also captures functional logic. • Inspect: Keep at least two possible causes open, then use one named object and the active mode or scenario to separate them. • Correct: Narrow the waiver record, fix any accidental objects, and prove the remaining set is identical after a clean rerun.
Command Checks & Actions
• check_netlist: reports structural connectivity problems
• report_ports -verbose [get_ports *]: shows boundary constraints and electrical assumptions
Run the commands in order. Each line answers a separate part of the check.Healthy, Suspicious & Hard-stop Results
• Expected: Require named-object evidence, functional reason, affected modes, owner, risk, and a rerun-stable waiver; never waive only a message count. • Investigate: A test output is intentionally unused, but the waiver pattern also captures functional logic. • Stop before floorplanning when required logic or timing coverage is missing or unexplained. Narrow the waiver record, fix any accidental objects, and prove the remaining set is identical after a clean rerun.
Common Mistake
Do not assume the check passed just because ICC2 continued: A test output is intentionally unused, but the waiver pattern also captures functional logic. Fix or narrowly justify the named objects, then rerun the same command.
What The Interviewer Is Testing
Be ready to explain why this matters before floorplanning: A test output is intentionally unused, but the waiver pattern also captures functional logic.
Follow-up Question & Model Response
Model response: “I would save the report, inspect one affected object in the correct block and scenario, and make or request this correction: Narrow the waiver record, fix any accidental objects, and prove the remaining set is identical after a clean rerun. Then I would reopen the clean checkpoint and rerun the same evidence.”
Practical Example
Symptom: A test output is intentionally unused, but the waiver pattern also captures functional logic. Corrective path: Narrow the waiver record, fix any accidental objects, and prove the remaining set is identical after a clean rerun.
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