open-source-silicon.dev

image.png

hi <@U016EM8L91B> when I select the top level cell of a standard cell, there is a white box showing the actual cell boundary, how do I make my custom cells do that too? for context my custom cells are being misaligned after gds streamout in openlane

<@U06C3K0JST1> See <https://open-source-silicon.slack.com/archives/C016H8WJMBR/p1597841404277400?thread_ts=1597817277.260000&amp;cid=C016H8WJMBR>

thanks, I tried it and the abutment box does show.

However it's still misaligning when magic does streamout

when magic take the .def file and add cells in to make a full gds, where does it take the abutment box information from? I added the FIXED_BBOX property and reextracted both the LEF file and GDS file and it is still misaligned

<@U06C3K0JST1> Just to be clear, you
1. added the `FIXED_BBOX` property
2. you created the lef and gds
3. you ran openlane
4. the cell does not appear at the correct coordinates

i see that in the magic tech file it's generating a separate gds layer for the abutment box, is it using that box to align with the sites during gds streamout?

Yes, it is supposed to be creating the GDS layer `prBoundary` in the position of `FIXED_BBOX`, and that is supposed to be a two-way operation.  It should be able to read back the `FIXED_BBOX` property from the `prBoundary` in the GDS.  There shouldn't be any misalignment.  What sort of misalignment are you seeing?

In LEF files, you might find it necessary to have the bounding box at the origin (for which you can use the `move origin` command).

i missed some stuff in the tech file, but it worked after adding `boundary` statements in cifinput and cifoutput