> is there any reason other than promoting the GPL [...]
Isn't that reason enough?
> why even have a syscall exception?
Because Linus is more pragmatic than RMS.
Also, syscalls are generally not Linux-specific, so it would be hard to argue that programs that use them are "works based on" Linux. Making the syscall exception explicit is, IMO, mostly a historic reassurance for proprietary driver/program vendors that code they wrote for AIX/Solaris/HP-UX/etc... can be recompiled for Linux without risking any compliance issues.
he probably is, but that is not the reason here. even RMS fully agrees that using it in the normal USING fashion does not trigger copyleft. This is why you can compile proprietary software with gcc, and similarly, when gcc had a java class library project, it was GPL+classpath exception
Isn't that reason enough?
> why even have a syscall exception?
Because Linus is more pragmatic than RMS.
Also, syscalls are generally not Linux-specific, so it would be hard to argue that programs that use them are "works based on" Linux. Making the syscall exception explicit is, IMO, mostly a historic reassurance for proprietary driver/program vendors that code they wrote for AIX/Solaris/HP-UX/etc... can be recompiled for Linux without risking any compliance issues.