So:
- A hardware device has closed-source firmware running inside it (not based on any open-source code).
- Computer software to update the hardware's firmware exists, with a GPLv3 license. It takes a binary firmware image file and writes it without any modification to the hardware.
- For the GPL software to recognize the hardware, the GPL software must be modified.
If a zip file is distributed with these things inside it:
- Binary for customer to run, compiled from the modified GPL software
- A nested zip file with source code for modified GPL software, to meet GPL requirements
- Binary firmware image for the hardware, without any source code
Is that legal?
Does the GPL license "infect" the binary firmware image, so that the entire zip file is considered a derivative work, and therefore requires that the hardware's source code also be distributed under GPL?
Or is the binary firmware image considered a separate work and can be distributed alongside it without any licensing issues?