Why record a manifest and file checksums?
From PDVerse PnR Interview Handbook · pdVerse Mentor Guide
Short Answer
A manifest connects every loaded file to a revision, producer, timestamp, mode, corner, and checksum so the run can be reproduced.
Technical Explanation
Think of the manifest as the packing list for the handoff. The checksum is the seal that tells you whether a file changed after that list was prepared.
What To Check
• Warning sign: A rerun produces different counts because a same-named file changed silently. • Inspect: Start with one named object in the report and trace it to the netlist, library, or SDC statement that created it. • Correct: Freeze the approved inputs, record checksums outside ICC2, and restart from the documented bundle.
Command Checks & Actions
• current_block: confirms the active design block
• report_ref_libs: shows the reference libraries used for linking
Run the commands in order. Each line answers a separate part of the check.Healthy, Suspicious & Hard-stop Results
• Expected: A manifest connects every loaded file to a revision, producer, timestamp, mode, corner, and checksum so the run can be reproduced. • Investigate: A rerun produces different counts because a same-named file changed silently. • Stop before floorplanning when required logic or timing coverage is missing or unexplained. Freeze the approved inputs, record checksums outside ICC2, and restart from the documented bundle.
Common Mistake
Do not assume the check passed just because ICC2 continued: A rerun produces different counts because a same-named file changed silently. 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 rerun produces different counts because a same-named file changed silently.
Practical Example
Symptom: A rerun produces different counts because a same-named file changed silently. Corrective path: Freeze the approved inputs, record checksums outside ICC2, and restart from the documented bundle.
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