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gf180: add Nwell masterslice layer to tech LEFs - #4699
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bandhambalaji wants to merge 1 commit into
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The GF180 platform technology LEFs define Poly2 as a masterslice layer but omit the process Nwell masterslice layer. When importing macro LEFs whose OBS sections declare Nwell geometry (such as GF180 SRAM blocks), OpenDB reports undefined layer Nwell (ODB-0176) and drops subsequent metal obstruction geometries. Declare LAYER Nwell TYPE MASTERSLICE across the GF180 technology LEFs so macro obstructions referencing Nwell parse cleanly without dropping routing obstructions. Fixes The-OpenROAD-Project#4496 Signed-off-by: Bandham Balaji <bandhambalaji@gmail.com>
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This pull request adds the Nwell layer definition, configured as a MASTERSLICE with the LEF58_TYPE property set to "TYPE NWELL ;", across multiple GF180 MCU technology LEF files. There are no review comments, and I have no feedback to provide on these changes.
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🔍 QoR checkMetrics reflect the PR merge build — i.e. what will land on the target branch. Commit 62 design(s) checked — 0 with regression(s), 0 without a comparable baseline. |
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Problem
In
flow/platforms/gf180/lef/, the platform technology LEFs declarePoly2as a masterslice layer but omit the processNwellmasterslice layer.When importing macros whose
OBSsections referenceNwell(such as standard GF180 SRAM macros generated for GF180MCU), OpenDB emits:Because
Nwellis encountered as the first layer in the macroOBS, the subsequentMetal1/Metal2/Metal3routing obstructions are silently dropped, leading to router shorts and detailed routing DRC violations inside the macro.Fix
Declare
LAYER Nwell TYPE MASTERSLICEwithPROPERTY LEF58_TYPE "TYPE NWELL ;"across the 24 stack-specific GF180 technology LEFs, matching the convention used in Sky130 and ASAP7.Verified that OpenROAD imports
gf180mcu_*_tech.lefand SRAM macros declaringNwellobstructions cleanly with zero warnings and preserves all subsequent metal obstruction geometries.Fixes #4496