The Debian Kernel team aims to provide kernels for our users that are functional, free, and secure, with a minimal divergence from upstream.

Patches the kernel team like:

This applies both to unstable and stable, though we are more conservative with updates to stable.

Patches the kernel team generally reject:

The best way to get a patch into the Debian kernel is to get it accepted upstream first. Not only does this signify a certain level of quality, but it gives us a guarantee that we will be able to drop this patch from our Debian-specific tree at some point.

Note: waldi explained in <20080717224521.GA3835@wavehammer.waldi.eu.org> when someone pointed to this page "Which is only the case for the main images. We have support for additional feature sets, which have less strict rules." and nobody objected (nor explained what the lesser rules were).