A lot of software is written specifically to run on Linux, but that
doesn't mean it's derived from Linux. In the case of user-space code
it's widely understood that no licence restrictions are conferred. The
argument relating to kernel modules is that a module is somehow
different because it runs in kernel mode. I can't see it, and in view
of the status of user-space code, strong arguments would have to be made.
No. Holders of Linux copyrights would have to prove that the
proprietary code is derived from the kernel. They have the burden of
proof, and defence needs merely show that their arguments are wrong.
(So if the proof is faulty, the case fails even if the code is derivative.)
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