Routing Resource Graph Generator Support on Obstacle Channels

[tangxifan]

I have been searching for if the routing resource graph generator supports trimming channel inside wide/tall programmable blocks. This is the option which seems to do the job:

vtr-verilog-to-routing/vpr/src/base/SetupVPR.cpp

Line 361 in 8508bbe

RouterOpts->trim_obs_channels = false; /* DEFAULT */

This is an internal switch of the router options which cannot be turned on/off through any command-line option or architecture XML syntax.
It is by default turned off, which means the routing channels always go through the programmable blocks, as shown in the figure below.

I tried to turn it on but I have seen segmentation fault during rr_graph building.

Expected Behaviour

• The option should be documented
• The feature should be accessible in the command-line options or architecture description language.

Current Behaviour

• No documentation about the switch.
• Not accessible through any user interface.
• Meet segmentation fault during rr_graph building when it is forced to be on.

Possible Solution

• Documentation
• Update user interface
• Bug fix

Steps to Reproduce

1. Check out VTR project
2. Turn on the switch trim_obs_channel
3. Compile
4. Run basic regression test perl run_reg_test.pl vtr_reg_basic

Context

Your Environment

• VTR revision used: latest master
• Operating System and version: CentOS 7
• Compiler version: gcc-8