Flexible Bindings for Type-Safe Embedded Operating Systems.

This paper presents the binding model implemented in Camille, an extensible operating system for resource-limited devices. Modern embedded systems need on the first hand to fully exploit the limited hardware on which they run and on the other hand to dynamically adapt themselves to changes in their runtime environment. Camille is an exokernel which support static customization of components and dynamic loading of system extensions. Dynamic kernel and application adaptation is implemented by an inter-component communication model. This model is based on flexible bindings which permit to fully customize the way components interact with each others. Bindings can be static, virtual or compiled to guarantee performances of inter-component communications. This paper shows that it is possible to build a flexible operating system without sacrificing runtime performances, even for devices as constrained as smart cards. We first present the architecture of the Camille exokernel and the intermediate language Facade into which applications and system components are translated to ease type verification. We then describe the component model implemented in Camille and the inter-component communication scheme based on embedded binding factories. We then details the binding generation process and the various verifications which can be enforced when implementing bindings. We present some experimental results we have obtained when monitoring the performances of our native code generator. Finally, we conclude and discuss the future work we plan to conduct concerning extraction of selected properties from generated code