"The GPL is Not Compatible with Itself"

A recent press conference of the Free Software Foundation confirmed the rumours that the GNU General Public License was found to be incompatible with itself. This newly discovered fact may actually cause a lot of disorder in the free software world in which most programs and libraries are licensed under this license.

Richard Stallman, chairman of the FSF, called upon developers to immediately exempt GPL-licensed software from the GPL, as far as linking them with GPL programs is concerned. "We have already made sure all GNU software and every other software that is licensed to the Free Software Foundation would be ad-hoc compatible with itself. However we need other developers to do the same for their software", Stallman said.

Eben Moglen, the FSF's attorney outlined the subsequent steps that his organization will take to overcome this crisis. The first step would be releasing a Modified General Public License (or MGPL for short) that will be compatible with the GPL and with itself as well as with all other licenses that the GPL is already compatible with. It will be labeled the GPL version 2.1, thus allowing developers to convert their software to it. He noted that care would be taken to make sure the upcoming GPL version 3.0 will be compatible with itself, as well as the MGPL.

For the time being, though, there is an explosion of commentary, confusion and otherwise bad temper about the newly formed situation. Eric S. Raymond, the famous Open Source Guru notes: "This is one of the greatest blows to the Open Source world, I have yet encountered. I have already exempted all of my own software from the GPL in this regard, but there is a lot of other software out there, and many of its authors are not very communicative.

Bill Gates, Microsoft's co-founder, on the other hand, seems to find the situation very amusing: "I said times and again, that viral licenses such as the GPL are a bad idea, and many open-source advocates disagreed. Now they see that even making sure one's license is compatible with itself, is hard to do when you open that can of worms."

The integrity of many software projects whose license is the GPL and yet contain works licensed by several developers is in jeopardy. The Linux kernel is a prominent example of such a case. In a post to its mailing list, Linus Torvalds commented that, in their case, it was not an issue. "My interpretation of the GPL is already quite unusual, so I'll simply rule that I also interpret the GPL as compatible with itself."

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This bit was originally published on 1 April on the iglu.org.il site.