Slightly off topic, but I think related: what's the legality of linking to a GPL library from a non-GPL binary, if you aren't distributing both together? (Or even if you do distribute both)
Lawyers representing ffmpeg/x264 seem to actively look to sue anybody that links to x264 from non-GPL binaries (x264 sell a commercial licence based on the fact that you can't link to x264 from non-GPL code). Yet statements like this, and the similar comments from Richard Stallman, seem to indicate that they won't have a case: using their headers does not subject you to the GPL since the headers are not covered by copyright, and if you don't include the library with your program but make it separate then you aren't distributing. At most you are asking your users to create a derivative work at runtime which may be covered by the terms of the GPL, but the GPL explicitly allows users to do what they like, as long as they don't distribute the result.
As far as I know this "no linking" aspect of the GPL has never been tested in court and appears to be very shaky.
This situation is different from ffmpeg. Kernels do not link to your program in the way that libraries do. When using a library, even a dynamically linked one, the memory image of your program is a combined work. As the CPU is evaluating your program, it does not see the library or treat it differently than any other functions in your program.
System calls can be thought of like RPC. The two programs (yours and the kernel) communicate but do not link together in a single memory image.
Yes, as I said the issue are slightly different. My question is: what legal basis does the developer of a GPL library have to sue somebody who released a program linked with that library. If the two only come together to form a combined work on the users machine, at the users command, then how does the GPL apply to me, the distributor of the the non-GPL program? I am not distributing a combined or derivative work. At most I am using the headers and distributing the symbol names, which are not covered by copyright. When I make no copies, how does copyright law affect me?
If the headers were covered by copyright, that would have provided a way for a developer to prevent use of their GPL library by non-GPL programs.
Your argument applies in the case where you do not distribute the GPL'd library - as zerohp points out, opinions differ on this case, and it hinges on whether your compiled program would be considered a "derivative work".
However, if you distribute the GPL'd library, then it's a lot more clear-cut. "Derivative work" doesn't enter into it anymore - to distribute the GPL'd library itself you must have a license to do so. If the license you're relying on there is the GPL, you must abide by its terms, including those about linking.
Lawyers representing ffmpeg/x264 seem to actively look to sue anybody that links to x264 from non-GPL binaries (x264 sell a commercial licence based on the fact that you can't link to x264 from non-GPL code). Yet statements like this, and the similar comments from Richard Stallman, seem to indicate that they won't have a case: using their headers does not subject you to the GPL since the headers are not covered by copyright, and if you don't include the library with your program but make it separate then you aren't distributing. At most you are asking your users to create a derivative work at runtime which may be covered by the terms of the GPL, but the GPL explicitly allows users to do what they like, as long as they don't distribute the result.
As far as I know this "no linking" aspect of the GPL has never been tested in court and appears to be very shaky.