Chipyard sky130A with OpenRoad

[arunlee77]

Hi,

I am following https://chipyard.readthedocs.io/en/stable/VLSI/Sky130-OpenROAD-Tutorial.html to understand the VLSI flow. The link above mentions about openroad versions (also other tools) which were seem to be working (or were working at some time).

My environment is ubuntu 22.04 on Intel Xeon server with 32 cores and over 92GB RAM.

It is not possible to install openroad version OpenROAD v2.0-7070-g0264023b6 using conda. So i proceeded to build and install the same githash. I have used cmake -DENABLE_VTUNE=OFF .. as the 2024.2 vtune (latest) from intel seems to be incompatible in terms of libraries available.

The build went fine and i started with the synthesis and par.

During par, the system hung (32 core Xeon) at step

``[par] [Exec ...l/bin/openroad -no_init -log /...] [NesterovSolve] Iter: 360 overflow: 0.283068 HPWL: 1126055571

Here are my changes in the configuration.

+++ b/vlsi/example-openroad.yml
@@ -9,3 +9,14 @@ vlsi.core.drc_tool: "hammer.drc.klayout"
 # vlsi.core.drc_tool: "hammer.drc.magic"
 # LVS: Netgen
 vlsi.core.lvs_tool: "hammer.lvs.netgen"
+par.openroad.global_placement.density: 0.7
+par.openroad.global_placement.iterations: 100
+par.openroad.global_placement.placement_padding: 7
+par.openroad.global_placement.routing_adjustment": 0.7
+
+synthesis.yosys.yosys_bin: /usr/local/bin/yosys
+par.openroad.openroad_bin: /usr/local/bin/openroad
+par.openroad.klayout_bin: /usr/local/bin/klayout  # binary that OpenROAD calls for final GDS writeout
+drc.klayout.klayout_bin: /usr/local/bin/klayout   # binary that runs for DRC step
+drc.magic.magic_bin: /usr/local/bin/magic
+lvs.netgen.netgen_bin: /usr/local/bin/netgen
diff --git a/vlsi/example-sky130.yml b/vlsi/example-sky130.yml
index 3f45bd3d..f82d3c6e 100644
--- a/vlsi/example-sky130.yml
+++ b/vlsi/example-sky130.yml
@@ -6,8 +6,8 @@ vlsi.core.max_threads: 12

 # Technology paths
 technology.sky130:
-  sky130A: "/path/to/sky130A"
-  sram22_sky130_macros: "/path/to/sram22_sky130_macros"
+  sky130A: "/home/robotics/chipyard/.conda-env/share/pdk/sky130A"
+  sram22_sky130_macros: "/home/robotics/chipyard/sram22_sky130_macros"

   # this key is OPTIONAL, no NDA files will be used if it does not point to a valid path
   sky130_nda: "/path/to/skywater-src-nda"

I proceeded to try changing the par parameters, but it has become more sluggish. The -j20 argument doesn't seem to have any effect too.

diff --git a/vlsi/example-designs/sky130-openroad.yml b/vlsi/example-designs/sky130-openroad.yml
index a686fbba..4040233f 100644
--- a/vlsi/example-designs/sky130-openroad.yml
+++ b/vlsi/example-designs/sky130-openroad.yml
@@ -20,19 +20,19 @@ par.openroad:
   global_placement.timing_driven: true
   global_placement.routability_driven: true

-  global_placement.placement_padding: 6
-  detailed_placement.placement_padding: 4
+  global_placement.placement_padding: 8
+  detailed_placement.placement_padding: 8
   clock_tree.placement_padding: 2
   clock_tree_resize.placement_padding: 0
-
+  global_placement.placement_iterations: 200
   clock_tree_resize.setup_margin: 0.0
   clock_tree_resize.hold_margin: 0.20
   global_route_resize.hold_margin: 0.60
   clock_tree_resize.hold_max_buffer_percent: 80

-  global_placement.routing_adjustment: 0.5
-  global_route.routing_adjustment: 0.3
-  global_route_resize.routing_adjustment: 0.2
+  global_placement.routing_adjustment: 0.7
+  global_route.routing_adjustment: 0.5
+  global_route_resize.routing_adjustment: 0.5

 # DRC/LVS configuration
 drc.magic.generate_only: true
@@ -45,8 +45,8 @@ vlsi.inputs.placement_constraints:
     type: toplevel
     x: 0
     y: 0
-    width: 4000
-    height: 3000
+    width: 40000
+    height: 30000
     margins:
       left: 10
       right: 0

I contacted chipyard mailing list, but the suggestion is to contact openroad developers !!

https://groups.google.com/g/chipyard/c/bH4Nx6cY9Sw

Do you guys know what is going on with my trials? Is there a working BKM for trying sky130 + openroad in chipyard/hammer context?

regards
Arun

[maliberty]

We don't test with hammer. How large is the design and how long did it hang? Can you try turning off -routability_driven and -timing_driven if you are using them.

[arunlee77]

Hi Matt,
Thank you for your suggestion, i put the routability and timing_driven to false in the sky130 openroad configuration. par proceeded a bit, it did not hang on the previous place, but is hanging at somewhere else.

[par] [Exec ...l/bin/openroad -no_init -log /...] [NesterovSolve] Iter: 430 overflow: 0.106414 HPWL: 1244630971
[par] [Exec ...l/bin/openroad -no_init -log /...] [NesterovSolve] Finished with Overflow: 0.099041
[par] [Exec ...l/bin/openroad -no_init -log /...] (hammer) estimate_parasitics -placement
[par] [Exec ...l/bin/openroad -no_init -log /...] (hammer) write_db pre_io_placement
[par] [Exec ...l/bin/openroad -no_init -log /...] (hammer) exec ln -sfn pre_io_placement latest
[par] [Exec ...l/bin/openroad -no_init -log /...] (hammer) place_pins -hor_layers {met5} -ver_layers {met4 met2} -exclude top:* -exclude right:* -exclude left:*
[par] [Exec ...l/bin/openroad -no_init -log /...] Found 5 macro blocks.
[par] [Exec ...l/bin/openroad -no_init -log /...] Using 1u default distance from corners.
[par] [Exec ...l/bin/openroad -no_init -log /...] Using 2 tracks default min distance between IO pins.
[par] [Exec ...l/bin/openroad -no_init -log /...] [INFO PPL-0010] Tentative 0 to set up sections.
[par] [Exec ...l/bin/openroad -no_init -log /...] [INFO PPL-0001] Number of slots          13922
[par] [Exec ...l/bin/openroad -no_init -log /...] [INFO PPL-0002] Number of I/O            79
[par] [Exec ...l/bin/openroad -no_init -log /...] [INFO PPL-0003] Number of I/O w/sink     79
[par] [Exec ...l/bin/openroad -no_init -log /...] [INFO PPL-0004] Number of I/O w/o sink   3
[par] [Exec ...l/bin/openroad -no_init -log /...] [INFO PPL-0005] Slots per section        200
[par] [Exec ...l/bin/openroad -no_init -log /...] [INFO PPL-0006] Slots increase factor    0.01
[par] [Exec ...l/bin/openroad -no_init -log /...] [INFO PPL-0008] Successfully assigned pins to sections.
[par] [Exec ...l/bin/openroad -no_init -log /...] [INFO PPL-0012] I/O nets HPWL: 111615.59 um.
[par] [Exec ...l/bin/openroad -no_init -log /...] (hammer) write_db pre_resize
[par] [Exec ...l/bin/openroad -no_init -log /...] (hammer) exec ln -sfn pre_resize latest
[par] [Exec ...l/bin/openroad -no_init -log /...] (hammer) estimate_parasitics -placement
[par] [Exec ...l/bin/openroad -no_init -log /...] (hammer) buffer_ports
[par] [Exec ...l/bin/openroad -no_init -log /...] [INFO RSZ-0027] Inserted 40 input buffers.
[par] [Exec ...l/bin/openroad -no_init -log /...] [INFO RSZ-0028] Inserted 35 output buffers.
[par] [Exec ...l/bin/openroad -no_init -log /...] (hammer) repair_design
[par] [Exec ...l/bin/openroad -no_init -log /...] [INFO RSZ-0058] Using max wire length 3431um.


[par] ERROR: OpenROAD returned with a nonzero exit code: -9.
[par] To create a tar archive of the issue, set:
            par.openroad.create_archive_mode: latest_run
        in your YAML configs and re-run your par command
[par] Did not run write_design
Action par config output written to output.json
(/home/robotics/chipyard/.conda-env) robotics@tmsbuild023:~/chipyard/vlsi$

Do you have any idea what is blocking now?

regards
Arun

[maliberty]

No, you need to make a proper issue with a test case.

[arunlee77]

What test case should i do?. As mentioned earlier, i am running the instructions from https://chipyard.readthedocs.io/en/stable/VLSI/Sky130-OpenROAD-Tutorial.html and am not an expert on openroad or hammer.

[arunlee77]

I have openroad version: v2.0-7070-g0264023b6 but the conda environment has a python3.10 based openroad (../.conda-env/lib/python3.10/site-packages/hammer/par/openroad/init.py ). Is there a compatibility issue here between the openroad and the python bindings?

I ran make par HAMMER_EXTRA_ARGS="--stop_after_step global_placement" tutorial=sky130-openroad and it is success, but when i try to run make redo-par HAMMER_EXTRA_ARGS="--start_after_step global_placement" tutorial=sky130-openroad the build failed with error

[par] [Exec ...l/bin/openroad -no_init -log /...] (hammer) read_db pre_io_placement
[par] [Exec ...l/bin/openroad -no_init -log /...] [ERROR ORD-0007] pre_io_placement does not exist.
[par] [Exec ...l/bin/openroad -no_init -log /...] Error: par.tcl, 135 ORD-0007

If i run with --start_before_step io_placement, also give the same error

[par] [Exec ...l/bin/openroad -no_init -log /...] (hammer) read_db pre_io_placement
[par] [Exec ...l/bin/openroad -no_init -log /...] [ERROR ORD-0007] pre_io_placement does not exist.
[par] [Exec ...l/bin/openroad -no_init -log /...] Error: par.tcl, 135 ORD-0007

This makes me believe that there is some kind of mismatch of the openroad and python binding and that's what is making it hang.
It seems like there are issues after the global_placement step.

Could you be able to see what python binding (version) is suitable for v2.0-7070-g0264023b6 (openroad) ?

[maliberty]

You'll need to ask the hammer team how to construct a test case from hammer. You might consider using OpenROAD-flow-scripts in which case I could offer more help.