A Case for Nano-Kernels

Abstract

The / Choices operating system splits the microkernel into a machine-independent part and a machinedependent sub-microkernel. The sub-microkernel, called the nano-kernel in tChoices, encapsulates the hardware and presents an idealized machine architecture to the rest of the system. Higher levels of the system access the nano-kernel through a single interface. Nano-kernels are useful because they significantly enhance portability of the entire microkernel. The interface provided by the idealized machine architecture of the t Choices nano-kernel is a good match for constructing higher-level abstractions in the machine-independent microkernel. In the t Choices nano-kernel, we have fully decoupled the nano-kernel from all higher-level abstractions. Thus, it should be possible to construct many different operating systems on top of the nano-kernel. The t Choices nano-kernel is built as an object-oriented framework. The framework guides porting to new hardware platforms, and allows the specialization of its components for efficient, machine-specific implementation.