Last modified: Sat Apr 9 03:11:32 2016 GMT.
In this paper, we present a novel language-based account of abstraction layers and show that they correspond to a strong form of abstraction over a particularly rich class of specifications which we call deep specifications. Just as data abstraction in typed functional languages leads to the important representation independence property, abstraction over deep specification is characterized by an important implementation independence property: any two implementations of the same deep specification must have contextually equivalent behaviors. We present a new layer calculus showing how to formally specify, program, verify, and compose abstraction layers. We show how to instantiate the layer calculus in realistic programming languages such as C and assembly, and how to adapt the CompCert verified compiler to compile certified C layers such that they can be linked with assembly layers. Using these new languages and tools, we have successfully developed multiple certified OS kernels in the Coq proof assistant, the most realistic of which consists of 37 abstraction layers, took less than one person year to develop, and can boot a version of Linux as a guest.