Tip: skipping IR drop analysis

[oharboe]

It can be useful to skip analyze_power_grid, if the analysis of the default power grid is causing problems.

The trick is that an empty environment variable is still detected as set by

OpenROAD-flow-scripts/flow/scripts/final_report.tcl

Line 39 in 8307935

if {[info exist ::env(PWR_NETS_VOLTAGES)]} {

To get around this, unset PWR_NETS_VOLTAGES and GND_NETS_VOLTAGES after the default values are set in the platform config.mk file:

OpenROAD-flow-scripts/flow/platforms/asap7/config.mk

Line 255 in 8307935

export PWR_NETS_VOLTAGES ?= "VDD $(VOLTAGE)"

This can be done by creating a private.mk file that is included at the end of the Makefile:

OpenROAD-flow-scripts/flow/Makefile

Line 803 in 8307935

-include $(PRIVATE_DIR)/private.mk

Create a private.mk file:

# Skip analyze_power_grid
undefine PWR_NETS_VOLTAGES
undefine GND_NETS_VOLTAGES

In the config.mk for your design, point to the folder where the private.mk file is located:

export PRIVATE_DIR = ./designs/$(PLATFORM)/mydesigname/

[maliberty]

You could also change the check to also skip on an empty string if that's easier.

[oharboe]

I prefer not to change ORFS and these checks as stated in the .tcl scripts are everywhere in the code, so I wanted a trick that worked in all other cases