What command order preserves the meaning of failures?
From PDVerse PnR Interview Handbook, part of the pdVerse Mentor Guide
Short Answer
Every sanity check depends on facts established by the check before it — run them out of order and a later "pass" can be meaningless, because it was built on unverified ground. Start with identity and libraries: confirm you're on the right design and the right library set before doing anything else.
Technical Explanation
- Then link the design, and immediately check for structural problems — unbound objects, broken hierarchy — because nothing downstream is trustworthy if linking is broken.
- Only after that: validate and apply SDC, inspect clocks/scenarios/exceptions for correctness, and finally run the timing-health checks. If linking failed, a clean clock report or exception report built on top of it isn't real evidence of anything — it's evidence built on a broken foundation.
What To Check
- Warning sign: Running one combined check first obscures whether the root cause is linking, structure, or constraints.
- Inspect: Compare one named object across the related reports; the same object should tell a consistent story.
- Correct: Run separate reports into distinct files and stop at the first dependency failure.
Command Checks & Actions
- current_block: confirms the active design block
- report_ref_libs: shows the reference libraries used for linking
check_design-checks {netlist unbound dp_pre_floorplan}: runs the selected design-readiness checks- check_netlist: reports structural connectivity problems
check_timing: finds missing or inconsistent timing setup
Run the commands in order. Each line answers a separate part of the check.
Healthy, Suspicious & Hard-stop Results
- Expected: Establish identity and libraries, link, check structure/unbound objects, validate and apply SDC, inspect clocks/scenarios/exceptions, then run timing-health checks.
- Stop before floorplanning when required logic or timing coverage is missing or unexplained.
Common Mistake
The Trap: Do not assume the check passed just because ICC2 continued. 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.
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. ”
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