What does report_mv_path show, and when do you use it?

Short Answer

report_mv_path (ICC2) traces one multivoltage path through a pin, net or cell and shows every MV cell on it with its supply, drivers, sinks, strategy and power domain. For a level shifter or isolation cell that failed to insert or associate, it prints the reason. You reach for it when check_mv_design (ICC2) flags a cell or net and you need to know why.

Technical Explanation

• Entry point: pass -cell, -net or -pin; the report follows that path from driver to loads, isolation by default, shifters with -level_shifter.
• Per MV cell: supply, inputs, outputs, drivers, sinks, matching strategy and power domain, so you see which strategy owns each ISO or LS.
• Failure reasons: for an LS or ISO cell that was not inserted or not associated, the report says why; the one-line check message does not.
• Supply source tags: a related supply printed with (Literal Supply), (Domain) or (CSN) came from a literal-supply port attribute, the domain primary, or the PG net connection.
• -all_heterogeneous_paths lists every driver whose loads have different related supplies. All other options are ignored when you use it.
• Timing in the flow: the guide runs it after placement, routing or optimization plus check_mv_design (ICC2), when the MV cells exist to report.
• For level-shifter failures along a whole global net, follow up with analyze_mv_design -level_shifter -through (ICC2).

# [ICC2]  icc2_shell
check_mv_design
report_mv_path -cell U_COP/DATA_UPF_ISO
report_mv_path -net U_COP/dbg_out
report_mv_path -all_heterogeneous_paths
analyze_mv_design -level_shifter -through U_COP/dbg_out

What To Check

• Each ISO or LS cell on the path names the strategy you wrote for that boundary.
• Driver and load related supplies match the domains: VDD1p0_SW for PD_COP, VDD0p9 for PD_CPU.
• The isolation cell supply is always-on (SS_AON), not the switched PD_COP rail.
• No failure reason appears for a cell the check reported clean.

Healthy, Suspicious & Hard-stop Results

• Healthy (illustrative): Every MV cell on U_COP/dbg_out shows a strategy name, SS_AON as isolation supply and a load in PD_CPU.
• Suspicious (illustrative): The isolation cell supply shows (Domain) and resolves to PD_COP: it would switch off with the domain it guards.
• Hard stop: The report prints an association failure for DATA_UPF_ISO, matching MV-071: no strategy owns the cell, so nothing guarantees its clamp.

What The Interviewer Is Testing

• Do you know which ICC2 command explains an MV cell, as opposed to one that only counts violations?
• Can you read a related-supply source tag and say where the supply came from?

Follow-up Question & Model Response

"When would you use -all_heterogeneous_paths instead of -net?"

Candidate Model Response: Use it when one driver fans out to loads on different supplies and you rely on source- or sink-based isolation. The -net form shows one path, while -all_heterogeneous_paths lists every driver whose loads disagree on related supply, with the boundary ports and load pins for each. That tells you where a source or sink strategy will and will not insert cells. It ignores every other option you pass with it.