Originally Posted by stress_junkie
People have generally taken a broad view toward what may or may not be installed on a Linux system. That is why restricted hardware drivers are allowed. If Linux were truly restricted to using only GPL software then it would have less chance of gaining market share.
A restriction that is not enforced is like not having the restriction.
This is utter nonsense.
The FSF and the Linux kernel team take their licenses very seriously, as do most open source projects. A copyright license on an operating system has absolutely no power to limit what programs you can run on the operating system, nor does the GPL try to reach to such absurd lengths.
The GPL is a copyright license and as such, it only covers things that one could consider derivative works. The issue with linking to a software library or using a kernel driver is tricky because different people will disagree on whether these things constitute a derivative work.
Using a software library probably does constitute a derivative work. The FSF certainly takes the view that it does. The argument is that when you link your program to a library, part of that library actually goes into your program and your program is tied to that library to make a new joint work. That's why there are libraries like the LGPL, which explicitly allow this type of linking without requiring that the linked program be released as LGPL.
The issue with drivers is similar, but more tricky. In a very real sense, a driver is tightly bound to the kernel. A kernel driver is compiled as part of the kernel, similar to a library, and you can argue that the result is a single joint object which falls under the range of copyright law. Other people disagree with this and opine that a driver is an object of its own, and not affected by the copyright license of the kernel. The only way to really settle this issue would be to go to court over it and have a judge decide whether writing a kernel driver constitutes a derivative work or not.
Notice how all this discussion is *very* far away from your suggestion that running a program on top of an operating system should be covered by the GPL. I'd like you to take a few moments to think about the absurdity of this. Consider this: Linux is not the only operating system with a copyright on it... *EVERY* *SINGLE* operating system has a copyright on it... That includes Windows and Mac OS for example... Microsoft has a copyright on Windows. If running a program on Windows constitutes making a derivative work that can be covered by copyright law, then Microsoft would have copyright claims over every single freakin program running on Windows... Microsoft would be able to sue Adobe for making Photosop. They could sue Mozilla for making Firefox. They could sue Skype, Kazaa, IBM, and everyone who has ever written a program that runs on Windows.
Do you see how absurd this is? Well, this is the implication of thinking that running a program on top of an OS is an action covered by copyright law.