Opening a L2N database created with custom devices


I'm experimenting with writing custom extractors for a LVS deck. For debugging, I would like to check the netlist without a compare stage., but the L2N netlist currently produced cannot be imported by the netlist viewer.

My experiment is actually closely following the example Matthias shared at . The same issue can be reproduce with the example, by following the steps:

  • Edit lvs.lylvs to add report_netlist("extracted.l2n"), say after line 25:
  • Run the LVS script.
  • Now open the gds and load extracted.l2n in the GUI with Tools > Netlist Browser. This fails with the message Invalid device class template: in line: 23 of [...]/lvs/custom_device/extracted.l2n.

That line 23 is


The right most string is an empty string and the LayoutToNetlist reader doesn't like it. What is missing in the code of the example to generate a valid L2N file ?




  • Hi @srooks10,

    thanks for this nice problem description.

    This is a bug of the reader. It should turn the empty string into a generic device, which is does not. This issue is probably easy to fix.

    I have created a ticket for this problem:


  • Hi Matthias,
    The fix works, I'm able to load the netlist now.
    Thank you!

  • Very good. Thanks for the feedback!

    I am going to release the fixed version soon.

    Best regards,


Sign In or Register to comment.