Major TODO items remaining:

* Patching mechanism: where are the debian and subarch-specific patches
  going to be available and how they are going to be applied.

* Naming of the subarch-specific header packages. For that some magic
  should be done in post-install.

* Looks like it would be optimal to have a common kernel-headers package
  which would contain common headers for all arches without unmerged patches.

* Various remaining kludges (stripping and sparc32/sparc64 stuff on sparc,
  for example).

* Get rid of the /lib/modules/<version>/source symlink.