We're using a lot of different kernel configurations on our servers running Gentoo Linux and Linux VServer. Kernels' configs depend on hardware and functions of every server. Every time new kernel is released and/or we need to enable/disable some features for all servers' kernels we have to update .config's manually. This process should be automated with some diff/patch stuff that will check if current server's config should be updated as well. It's important that some common features should be activated everywhere while some specific (e.g. hardware) options should remain as they were configured for this server only.

So, what we're looking for is some automated tool for managing differents in kernel configurations. We don't think this task is something unusual but googling hasn't helped in any way.

Are there some tools for our needs?