It's not so simple

> This is true -- i.e. it's possible to do that modification, even without the patches, and the information is available elsewhere for those who invest the time to do the detective-work.

In theory, there is one kind of modification which is helped by the presence of the patch list, namely reverting a patch. In practice, riel said above that on a modern kernel this is made much harder by the fine-grained structure of the patches. I'll take his word for it.

But if you agree with me that you can do the same work with an upstream clone, you're not talking about _that_ modification, you're talking about _another kind_ of modification. You're talking about one of the following:

1) backporting a patch into the Red Hat kernel from stable, or upstream, or from another distro kernel. In this case the patch wouldn't obviously be in the Red Hat SRPM, so the patches wouldn't help.

2) backporting a patch from the Red Hat kernel to stable, or to the Debian kernel (it is not a coincidence that the problem was raised by a Debian kernel maintainer). In this case the patches obviously help, but in this case you're not talking about modifications to the Red Hat kernel! And the GPL talks about "preferred form for modification" of what you're distributing, not modification of something else.

Besides, I would rather avoid talking about the spirit of the GPL, since it is a very multifaceted spirit. For example, unlike other licenses it includes the "right" for you to make money on Free Software (for example from support), and Red Hat is obviously exercising it.