Do I need to abide GPLv3 if I use GPLv2 only libraries?

If all your libraries state they are "GPLv2" or "GPLv2 or later" or "GPLv2 only", then you only have to obey the GPLv2.

So basically as long as you avoid any libraries that are GPLv3, you should be fine.

You won't be able to prevent people running your application (ie. the GPL code that you release) on other hardware though. As per the terms of the GPL, any combined work can be distributed and used by anyone as long as they abide by the terms of the GPL. They can build it from source and run it wherever they want.

Just to be entirely clear, if you use GPLv2 libraries, you must release both the source code to the libraries and the source code to the application you build on top of those libraries.

(It is worth mentioned however that you are most likely breaking the spirit of the license, even though you are [probably] fully compliant legally. Different libraries will have different interpretations of what they consider the spirit of the license to be.)

I'm not a lawyer, this isn't legal advice, you should ask a lawyer if you have any doubts.

hi Joseph, thanks for the answer, what do you mean by "You won't be able to prevent people running your code on other hardware". Thanks

Kurzack 2010-09-27 05:53:00

@Kurzack: you have to release your code under GPL v2, and that says that people can modify the code for their own purposes, and then run it on their machines. If you don't like that, don't use GPL code.

Jonathan Leffler 2010-09-27 05:55:46

It's also worth noting that a lot of the additions in GPL3 were not just "new things," but things that people *thought* the GPL2 already covered, but not explicitly. For example, many people hold that GPL2 would provide the same protection against patent problems as the GPL3, it's just made clearer in the GPL3. (None of that has been tested though, so it's all just a big shouting match until it is.) This may be the case with Tivoisation too, but I'm not sure.

detly 2010-09-27 06:05:17

@Kurzack: Jonathan summarized it nicely. Just to be clear, when I say "your code" I mean the parts you have to release under the GPL. People can take that code and use it as they wish (within the confines of the GPL). I'll update my answer to make the clearer.

JosephH 2010-09-27 12:04:40

@detly Tivoisation is an odd case. It mainly (though not entirely) refers to the linux kernel, and Linus himself has explicitly stated that he feels Tivo are compliant with the GPLv2, and that he is happy for linux to be used in the way Tivo are using it.

JosephH 2010-09-27 12:06:08

@JosephH - honestly, Linus' feeling is no more important than Jane Q. Blogger's. The judge's opinion is the one that counts :) But it's a real can of worms, and I'm not arguing that it would go one way or the other — simply that just because something is explicit in GPL3 and not GPL2, it **doesn't** mean that GPL2 does not cover it anyway.

detly 2010-09-27 12:47:33

Linus's opinion is still important - no one is likely to sue over a GPL violation involving the linux kernel if Linus has said he doesn't think it's a violation... the judge's opinion only matters if the copyright holders and/or project leader(s) think it is a violation, as they're the only ones who can start legal action, and they're the ones that know their *intention* when picking the GPLv2. Intention can be as important as the actual written license in many jurisdictions. (I agree for the general GPL2 case it is much less clear)

JosephH 2010-09-27 13:23:14

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Do I need to abide GPLv3 if I use GPLv2 only libraries?

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