qflow(1) Open-Source Digital Synthesis Flow


qflow [processes] [options] <module_name>


This is the main executable for a complete tool chain for synthesizing digital circuits starting from verilog source and ending in physical layout for a specific target fabrication process. In the world of commercial electronics, digital synthesis with a target application of a chip design is usually bundled into large EDA software systems. As commercial electronics designers need to maintain cutting-edge performance, these commercial toolchains get more and more expensive, and have largely priced themselves out of all but the established integrated circuit manufacturers. This leaves an unfortunate gap where startup companies and small businesses cannot afford to do any sort of integrated circuit design.

Qflow tries to fill this gap.


Synthesize verilog source
Run initial placement
Static timing analysis
Run placement and route
Run congestion analysis, final place and route
Remove temporary working files
Display routed result
Run scripts synthesize to route
Run scripts synthesize to display


-T, --tech <name>
Use technology <name> (Default: osu035)
-p, --project <name>
Project root directory is <name>


The simplest way to use qflow is to be in a directory with one Verilog file called input.v and execute:

   qflow build input.v
This will run all the necessary steps in order to produce a layout of the specified Verilog file. If only certain steps are desired, one may first run:

   qflow input.v
and then open qflow_exec.sh and uncomment the desired steps, and at last run:

It is also possible to change other "project-specific" details in the files qflow_vars.sh and project_vars.sh which also have been created in the current directory.


qflow looks for technology files under /usr/share/qflow/tech. A shell script must be placed in a sub directory there declaring where each of the technology files are located:

Usually, the files needed are placed in the following locations:

If no technology name is specified on the command line with the -T/--tech option, it will attempt to use the default technology which is "osu035".

If the technology files are located somewhere else, this can be specified in qflow_vars.sh which is created when running qflow. The variables "techdir" and "techname" must be changed accordingly.


This manual page was written by Ruben Undheim <[email protected]> for the Debian project (and may be used by others).