In a commercial project for our customer, I would like to install a driver on all target machines. The driver is on sourceforge (http://com0com.sourceforge.net/). The website states that:

The Null-modem emulator is an open source kernel-mode virtual serial port driver for Windows, available freely under GPL license.

without further details on which GPL version or what the implications may be. I do not intend to use the source code. Using the provided installer would suit me well enough.

The question is now if there are any legal implications if I want to install the driver with our closed source software (e.g. from a single installation script) in a commercial project.

Any advice would be greatly appreciated.


According to the file license.txt included in the com0com archive, it uses the GPL version 2. (thanks @Brandin)

We will be installing all software on the target computer and ship the entire machine to the customer.

No specific dependency will be made to the driver. Our closed source software will just open an existing COM port via standard Windows API functionality.

  • 2
    According to the file license.txt included in the com0com archive, it uses the GPL version 2.
    – Brandin
    Sep 2, 2019 at 15:33
  • How are you going to distribute the com0com software with your product? For example, will your script fetch it from sourceforge.net, will you include the installer on some medium like a disc or USB key? Etc.
    – Brandin
    Sep 2, 2019 at 15:35
  • 2
    How is your software depending on this driver? Does your software work with anything that provides a COM port, or are you depending on the specific characteristics of this particular driver? Sep 3, 2019 at 6:24
  • @Brandin We will be preinstalling it and ship the entire machine
    – helb
    Sep 5, 2019 at 7:58
  • @BartvanIngenSchenau No explicit dependency will be made, see my update.
    – helb
    Sep 5, 2019 at 7:59

1 Answer 1


There are some legal implications for using a GPLv2 licensed driver, but they are not very onerous.

The main requirement is that you inform your customers about the fact that GPLv2 licensed software is being used, tell them which software it is, tell them where to obtain the sources for the exact version you are distributing (you may have to host them yourself to ensure they are available long enough) and give them a copy of the GPL license text. As the driver is under the GPLv2 license, you are not required to make it possible that your customers are able to replace the driver on the hardware you are supplying.

As your proprietary software does not depend on this particular diver (it just needs a driver that provides serial communications) and you are only interacting with it through the normal OS APIs, your software is considered to be an independent work as far as copyright is concerned. This means that the copyright license of the driver does not affect in any way what copyright license you can use for your proprietary software.

  • Great. This largely confirms my gut feeling.
    – helb
    Sep 5, 2019 at 10:51
  • 1
    "... and give them a copy of the GPL license text" - Don't forget to give them the source code to the GPL software itself. Generally you must provide the source code to the same version that you distributed, so saying something like "go download the source from the web site" would not be sufficient.
    – Brandin
    Sep 5, 2019 at 13:36

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