For those of us that can read source code there are a couple of strong indications that the Linux copyright holders still believe that Linux kernel modules may not necessarily constitute derivative works:<p>1. Every Linux kernel module can tell the kernel what license regulates its use, using the MODULE_LICENSE() macro. The Linux kernel keeps track of which modules are under GPLv2 (and a few other compatible licenses). When a module under a presumably &quot;proprietary&quot; license is loaded the kernel will mark itself as &quot;tainted&quot;. (It could just as well refuse to load the module, but it doesn&#x27;t.)<p>2. There are two macros used to export Linux kernel symbols: EXPORT_SYMBOL and EXPORT_SYMBOL_GPL. The former will make the symbol available to all kernel modules, while the latter makes it available only to GPL-licensed kernel modules. The clear purpose and motivation is that a kernel module that needs access to a symbol exported with EXPORT_SYMBOL_GPL must be a derivative work, while a kernel module that only depends on symbols exported with EXPORT_SYMBOL is not necessarily a derivate work.<p>Also, IANAL, but from a purely legal perspective I think it would be difficult to get a court to agree that a user space program that talks to the Linux kernel through system calls is never a derivative work, while a kernel module (even one that accesses only symbols exported with EXPORT_SYMBOL) is always a derivative work. The system call versus dynamic loaded module distinction is simply not very relevant from a purely legal perspective.