Research Of Memory Protection Model Of Component-Based Elastos Operating System

As a result of rapid development of computer technique and network computing,computer has been applied to more and more areas, and the diversities in applicationsoftwares are being increased. Different application areas and softwares havedifferent requirements which are imcompatible with each other, as is obvious inembedded application areas. These request that operating systems have bettermodularity and extensibility, and obviously traditional operationg systems cannot dothis because their fixed abstraction.In order to solve the problem, based on the basic ideas of component technique,micro-kernel operating systems, dynamically extensible operating systems andapplication-specific operating systems, Elastos operating system provide support forcomponent technique in kernel, and provide coarsely granular extensibility via agilekernel technique based on components. In order to provide better support for networkcomputing, Elastos implements the mechanism of components' auto-downloadingand running, and can implement the mechanism of clicking and running in webbrowsers based on it.But agile kernel and components' auto-downloading and running bring greatthreats against information security of Elastos operating system, and these threats arebased on components. In order to solve these threats, Elastos must implementmemory protection and code-security mechanism based on components and thememory protection is more elementary. This thesis provides one kind of memoryprotection model based on components and implements one prototype based on pagetable mechanism.The research results of the thesis include:1. It introduces the static structure and the running structure of applicationsin Elastos, and gives one method of supporting it.2. Based on the static structure and the running structure of applications, itintroduces one kind of model of protection against objects based onhierarchical fine-grained protection domain. The main idea of the modelis to divide the address space of processes into fined-grained addressranges, and every range forms one protection domain, and these domainsare isolated from each other by mechanishms provided by software orhardware.3. It analyzes major problems in implementing the fine-grained protectiondomain model, and introduces solutions based on software or hardwarefor every problem, and compares them simply.4. It introduces the prototype implemented in Elastos operating system.