One of the problems with micro-kernels is that everyone re-invents abstractions over the basic kernel services. Micro-kernels might be useful in some subset of

One of the problems with micro-kernels is that everyone re-invents abstractions over the basic kernel services. Micro-kernels might be useful in some subset of cases, but it is still useful to have an OS layer above the micro-kernel at which point maybe the micro-kernel is not so useful after-all as a general purpose OS mechanism.