“Linus Torvalds first released the Linux Kernel in September of
1991 under a very restrictive license requiring that the source
code must always be available, and that no money could ever be made
off of it. A few months later, he switched to the GPL, or GNU
General Public License, the license that has been used for the
Linux kernel source code ever since. A recent thread on the lkml
discussed some of the gray areas of legality where it’s not
explicitly clear what the GPL allows. Alan Cox was one of many
kernel developers to offer some insights…”