Heard of a deconstructed kernel project?

I recall seeing a project for assembling a kernel out of parts that were deliberately factored/deconstructed so as to maximize separation. Does anyone know of such a开发者_JS百科 project? It goes without saying I need it to be Open Source.

That sounds roughly like a microkernel. Obvious examples that are available for download include Minix and Mach. Note that while CMU no longer develops Mach, it is in active development and use elsewhere (e.g., as the core of Apple's Darwin).