I know that editing GPL source code is considered as a "modification", which means all the copyleft rules apply.

However, most software includes configuration files and makefiles which you can tweak before rebuilding. Does that count as modification?

For example, I am using the swupdate package through Yocto. I override the meta-swupdate layer to specify specific configurations (e.g. CONFIG_LUA_PARSER=y to enable LUA parser), and then build swupdate.

1 Answer 1


Section 1 of the GPLv3 states:

The “Corresponding Source” for a work in object code form means all the source code needed to generate, install, and (for an executable work) run the object code and to modify the work, including scripts to control those activities.

The Corresponding Source need not include anything that users can regenerate automatically from other parts of the Corresponding Source.

So Makefiles are clearly included if they exists.

The point of the GPL is to let the user be free to modify the code. A lot of projects are very hard to modify without the scripts used to fetch dependencies & build the executable so not providing means to build the code would go against the license spirit.

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    For makefiles, that make sense. But for build configurations, that's a gray area for me. On one hand, the developer exposed configuration flags for us to create builds that include or exclude certain features in the final binary, so it feels like not a modification, but simply an "option" or variant that is offered by the original code. On the other hand, we are rebuilding the code, so it's not really the same as the "official" build (if exists), so it feels like a modification to me. I'm lost on this one.
    – Ryuu
    Oct 25, 2019 at 3:01
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    @Ryuu Note that when redistributing a GPL software you have to provide the sources whether or not you modified them!. You cannot just say "it's the same as the original, look it up on the author website. That's against the license .You must, yourself, provide the source code, whether you modified it or not. So it doesn't really matter whether changing the build setup is a modification or not, if you are distributing the binary result you have to also provide the sources used to build that binary.
    – Bakuriu
    Oct 28, 2019 at 20:13
  • Agree, and I have no issues providing the source and config changes for that third party item. The concern is whether I've violated the modification part, which then due to copyleft, my own program becomes GPL as well.
    – Ryuu
    Oct 28, 2019 at 23:30

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