[yjftsjthsd-h]

My understanding is that it's to intentionally discourage trying to keep things out of tree, where they will inevitably break in worse ways. It also makes the GPL enthusiasts happy, but I doubt that was Linus's big goal.

[mehrdadn]

I see, thanks. I'd be curious as to why he feels it would "inevitably break in worse ways", seeing as how that's not really the case on other platforms.

[yjftsjthsd-h]

Basically, if you're going to have drivers out of tree, the driver ABI has to be perfectly stable, which restricts internal refactoring. Otherwise things break - and this does happen elsewhere; lots of drivers for Windows XP don't work on 10.