Research And Design Of Embedded Micro-Kernel Operating System Based On Multi-Core Architecture

With the fast development of embedded system industry, the performance of the operating systems on the embedded devices is more and more important. Reliability, real-time and security are the three most wanted feature of embedded operating system and on these three aspects, micro-kernel operating systems have a better performance comparing to traditional monolithic-kernel operating systems. L4, as the representative of second generation micro-kernel operating system, not only greatly improves its IPC efficiency, but also fits the requirements of embedded systems very well. However, current micro-kernel operating system cannot support multi-core architecture, while multi-core architecture is becoming more and more popular in the embedded system field. The task of this paper is to design a micro-kernel operating system which is suitable for multi-core embedded platform based on the current L4 micro-kernel.Based on the characters of the embedded systems, this paper adopts the concept of split model, which deploys a micro-kernel on each processor core, as the general design. There is also synchronization between these kernels to make them work together. For memory management, the design of this paper allows different threads of the same task running on different processor cores, which means that the address space of the task can be across the kernel boundary. On the other hand, the structure used to save address space mapping relationship, MapDB, will have only one instance and shared by all kernels. For thread schedule, the design of this paper limits the fine-grain schedule inside the processor core and provides a thread migration mechanism for cross-core schedule. For inter thread communication, this paper designs a mailbox system for cross-core communication and transparency is realized through proxy threads. For service applications running on micro-kernel, the design of this paper provides independent mode, master-slave mode and distributed mode.This paper provides a design of micro-kernel operating system based on multi-core architecture, which fits embedded environment very well. The mailbox system design fully leverages the shared L2 Cache character of multi-core architecture and has a good performance on cross-core communication. The idea of using split model in the general design provides the operating system a lot of application scenarios that fit embedded system's reliability, real-time and security requirements. The design in this paper is not only used in the project cooperated with Intel: Enhanced Virtualization Based on Micro Kernel Architecture (Intel university sponsored project), but also provides a reference design for other micro-kernel operating systems.