GPL and linking
Posted Feb 16, 2006 8:19 UTC (Thu) by khim
In reply to: GPL and linking
Parent article: On the dual-license model
Can we consider the latest Oracle investments as a confirmation that the linking clause in GPLv2 would likely hold in the court of law?
No. This clause is almost totally irrelevant to dual-licensing model.
I think you are mixing issues. Consider two samples.
1. I created nice MegaPuperProgram - and it can use libreadline if it's already installed on target system. I do not distribute libreadline itself. Can I distribute my work legally ? Who knows. It's not clear if my work is derived work of libreadline or not. Especially if my program is perfectly functional (but without command-line editing, of course) without libreadline.
2. I've created my SuperPuperProgram and have put MySQL in the same package (may be on the same CD or merely in the same box) and claim that even if my SuperPuperProgram is not usable without MySQL it's not GPL-violation (since I've used old LGPL'ed mysqlclient drivers or something). Hmm... Interesting. Box with SuperPuperProgram and MySQL is clearly derived product of MySQL. And you can only distribute MySQL in package if it's "mere aggregation". But if your program is not functional without MySQL... then how the hell can you call it "mere aggregation" ?
Think about it: when dual-licensed MySQL (or QT, or something else) is used you are firmly in situation number 2 for 99% cases. Where "linking clause" of GPLv2 is irrelevant. If you are distributing box with two totally unrelated packages (Apache and Bash, for example) - you are still distributing something derived from Apache and Bash (think about verses collection - you need specific permissions from all copyright holders and if poet B is loathing poet A and does not want to see such collection - you are stuck; no linking - verbs are totally independent from each other). Then. How the hell you can distribute RedHat Linux at all ? Oh, it's easy. With GPLv1 - you can not. With GPLv2 - you can since "mere aggregation" exception clause was added fifteen years ago. But it's kinda hard to claim that MySQL and your SuperPuperProgram are merely aggregated on the same media if your SuperPuperProgram is unusable without MySQL...
In short: dual-licensing model depends on differerent part of GPLv2. On limits for "mere aggregation" clause - and that's totally different story. This is why clarification about inability to use dynamic linking to avoid GPL requirements is in appendix: it's just explanation, not something required by GPLv2 machine - it'll work just fine without any appendix at all.
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