By coming out publicly opposing the Oracle takeover of Sun Microsystems, the godfather of open source, Richard Stallman, shocked some people in the open source community when he didn't outright condemn MySQL's practice of selling license exceptions.
Anyone who's followed Stallman's open source software advocacy, could reasonably assume that Stallman would be opposed to selling anything resembling an exception to the GNU General Public License, but you'd be wrong.
In a recent blog post Stallman, the president of the Free Software Foundation, said that selling exceptions to the GNU GPL is "acceptable."
"I've considered selling exceptions acceptable since the 1990s, and on occasion I've suggested it to companies. Sometimes this approach has made it possible for important programs to become free software," Stallman wrote.
"Selling exceptions depends fundamentally on using a copyleft license, such as the GNU GPL, for the free software release. A copyleft license permits embedding in a larger program only if the whole combined program is released under that license; this is how it ensures extended versions will also be free."
For Stallman it is a question of ethics and the copyright owner's commitment to free and open software.
"When I first heard of the practice of selling exceptions," Stallman wrote, "I asked myself whether the practice is ethical. If someone buys an exception to embed a program in a larger proprietary program, he's doing something wrong (namely, making proprietary software). Does it follow that the developer that sold the exception is doing something wrong too?"
"Clearly it is possible to develop powerful and complex software packages under the GNU GPL without selling exceptions, and we do," Stallman said. "MySQL can be developed this way too."
However, for good or bad, Stallman acknowledged the reality that MySQL developers do sell exceptions to fund MySQL development.
And while Stallman doesn't offer a ringing endorsement for the practice of selling noncopyleft license exceptions, he did say that in certain situations the practice can be "acceptable."