On breaking things

On Fri, Nov 19, 2010 at 12:04:47PM -0800, Linus Torvalds wrote:
> On Fri, Nov 19, 2010 at 11:58 AM, <david@lang.hm> wrote:
> >
> > how far back do we need to maintain compatibility with userspace?
> >
> > Is this something that we can revisit in a few years and lock it down then?
>
> The rule is basically "we never break user space".
>
> But the "out" to that rule is that "if nobody notices, it's not
> broken". In a few years? Who knows?
>
> So breaking user space is a bit like trees falling in the forest. If
> there's nobody around to see it, did it really break?

so test -rc kernels and see if they break something for you.

once it's released there's far less pressure to revert something, but during the -rc series it doesn't take much to trigger a revert.