On Mon, Feb 22, 2016 at 11:15:09AM -0800, Doug Anderson wrote:

> Note that historically I remember that Linus Torvalds has stated that
> there is no stable API within the Linux kernel and that forcing the
> in-kernel API to never change was bad for software development.  I
> tracked down my memory and found
> <http://lwn.net/1999/0211/a/lt-binary.html>.  Linus is rabid about not
> breaking userspace, but in general there's no strong requirement to
> never change the driver API inside the kernel.  That being said,
> changing the driver API causes a lot of churn, so presumably changing
> it in a backward compatible way (like adding to the API instead of
> changing it) will make things happier.

You do need to fix the users though, change is fine but you can't cause
people's systems to break.