Klayout LVS check failed on GCD (Sky130hd)

[maliberty]

Discussed in #4457

^{Originally posted by Blueonics August 21, 2026}

Issue

KLayout DRC passes cleanly on sky130hd designs, but KLayout LVS (flow/platforms/sky130hd/lvs/sky130hd.lylvs) reports ERROR : Netlists don't match. On ORFS gcd (sky130hd), the extracted netlist is missing most of the top-level module ports: only 28 of 74 pins on the gcd top cell are recognized, and the deck gives no further diagnostic.

Environment

• Upstream commit: 02ba50d5365a78304115e759c5957a1770452f8d (master)
• KLayout version: 0.30.7
• Design: gcd (sky130hd), also observed on a larger aes build
• DRC: clean (sky130hd.lydrc) — LVS: fails (sky130hd.lylvs)

Reproduction

cd flow
export DESIGN_CONFIG=./designs/sky130hd/gcd/config.mk
make finish
make lvs
# → ERROR : Netlists don't match, no further detail

Observations

LIPIN     = polygons(67, 16)
MET1PIN   = polygons(68, 16)
MET2PIN   = polygons(69, 16)
MET3PIN   = polygons(70, 16)
MET4PIN   = polygons(71, 16)
MET5PIN   = polygons(72, 16)
POLYPIN   = polygons(66, 16)
NWELLPIN  = polygons(64, 16)
RDLPIN    = polygons(74, 16)

Text labels are attached only to the drawing layers:

connect(NWELL, NWELLTXT)
connect(POLY, POLYTXT)
connect(LI, LITXT)
connect(MET1, MET1TXT)
connect(MET2, MET2TXT)
connect(MET3, MET3TXT)
connect(MET4, MET4TXT)
connect(MET5, MET5TXT)

Tried patching this, but did not resolve the issues.
No local changes were made to GCD, any help is appreciated.

[jeffng-or]

When I run with bd55fb1, I'm getting a different error:

/usr/bin/python3 /workspace/klayout_lvs/OpenROAD-flow-scripts/flow/scripts/run_command.py --log /workspace/klayout_lvs/OpenROAD-flow-scripts/flow/logs/sky130hd/gcd/base/6_lvs.log --tee -- \
        /workspace/klayout_lvs/OpenROAD-flow-scripts/flow/scripts/klayout.sh -b -rd in_gds="results/sky130hd/gcd/base/6_final.gds" \
        -rd cdl_file=/workspace/klayout_lvs/OpenROAD-flow-scripts/flow/objects/sky130hd/gcd/base/6_final_concat.cdl \
        -rd report_file=/workspace/klayout_lvs/OpenROAD-flow-scripts/flow/results/sky130hd/gcd/base/6_lvs.lvsdb \
        -r ./platforms/sky130hd/lvs/sky130hd.lylvs
KLayout 0.30.7
ERROR: In ./platforms/sky130hd/lvs/sky130hd.lylvs: Can't find a value for a R, C or L device in /workspace/klayout_lvs/OpenROAD-flow-scripts/flow/objects/sky130hd/gcd/base/6_final_concat.cdl, line 5712 in Netlist::read
ERROR: RuntimeError: Can't find a value for a R, C or L device in /workspace/klayout_lvs/OpenROAD-flow-scripts/flow/objects/sky130hd/gcd/base/6_final_concat.cdl, line 5712 in Netlist::read in Executable::execute
  ./platforms/sky130hd/lvs/sky130hd.lylvs:19:in `execute'
  :/built-in-macros/lvs_interpreters.lym:31:in `instance_eval'
  :/built-in-macros/lvs_interpreters.lym:31:in `execute'
Elapsed time: 0:01.25[h:]min:sec. CPU time: user 1.11 sys 0.10 (96%). Peak memory: 430280KB.
make: *** [Makefile:766: results/sky130hd/gcd/base/6_lvs.lvsdb] Error 1

[maliberty]

@jeffng-or is there something illegal in the 6_final_concat.cdl OR generated?

[jeffng-or]

The sky130hd CDL files included in the concat'd CDL file have a couple of issues:

• "short" placeholder for resistors (worked around locally by replacing "short" with 0)
• Additional "/" in instance definitions (KLayout interprets the "/" as an extra pin, so worked around locally by removing the "/")

With the workarounds in place, I'm now seeing the:

ERROR : Netlists don't match

Digging into it some more...

[jeffng-or]

I have gcd working, so testing against the rest of the sky130hd designs.

[jeffng-or]

Have an updated solution that seems to work for gcd, ibex, and jpeg. Re-testing