hello, I have been trying to harden a risc-v core for nearly over a week now but i just cannot get rid of the high congestion issue, even if i use 40mm^2 die area (which is huge since i only have 4kb cache and one 32bit in-order core) it still gives this same error. I don't know what to do now, any ideas will be appreciated!

@apothem Do you have 4 or 5 hard macros?

only 4 (two for labels and two for data)

Share the issue_reproducible as zip file

issue_reproducible.zip

ideas to try: Try smaller area with around 30-50-70 utilization (use relative size) Idea 2: Put macros closer or it might not be able to route the design

@apothem Not able to read attached odb file>

openroad> read_db tmp/cts/12-wrapper_islemci.resized.odb 
read failed on database stream (unexpected end-of-file encounted).
while evaluating read_db tmp/cts/12-wrapper_islemci.resized.odb

Can you check at your end? Which version of OpenLane you're using?

I am using the latest commit from OpenLane repo

Are you using fixed macro location?

yes, i am using placement config for them otherwise it forces them to be in the corners

But is that causing any congestion issue?

yeah i think so unfortuneatly, that's why i'm trying to use manual placement

It should not happen. Can you share your design files as zip?

i don't know if you meant that with "design" but since it is not a public project for now i can't share the .v files,

without test case it's difficult resolve the issue. Try with different density/core size/ cell padding/ macro place halo/ auto macro placement such different configuration to resolve congestion issue.

thank you so much, i've already tried a lot of density - core size configurations but never tried cell padding or macro place halo

low density can cause the same issues

okay, i will give it a try, thank you!

Padding is probably the easiest way to spread things out - you have lots of extra space

The problem is with openlane by default 0 cell padding set. So user have to update that.

i've tried smaller floorplan with smaller spacing and changing default cell padding but nothing seems to change unfortunately, i will try to harden other submodules and try hierarchical design instead :(