X86体系中保护模式下的内存访问机制

Memory Accessing Mechanism of X86 Computer System In Protected Mode

保护模式是X86体系结构的一种重要的工作方式 ,为在X86平台上实现的多任务、多进程操作系统提供了相应的硬件支持。在计算机的底层开发过程中 ,了解计算机体系结构中的主要部件 -内存的工作方式是及其重要的。文章介绍了当前较流行的微机体系结构 -X86系统中的内存的组织、管理、和访问机制 ,分析了X86在保护模式下分段机制、分页机制中的一些主要的数据结构和相应的硬件支持 ,并详细描述了分段机制中逻辑地址到线性地址的转换 ,分页机制中虚拟地址到物理地址的转换过程。通过分页和分段机制 ,可以实现多进程操作系统中的进程独立地址空间 ,以及对操作系统中内存的保护措施 。

Protecting mode is on importmant working method of X86_based computer system,which provides the hardware support for multi_task and multi_process operation system on X86 platform. During the low_level development of X86_based computer system,it is very important to understand the working method of memory that is a main part of computer system. This paper discusses the data structure and hardware component of X86_based computer system which support the two mechanism of accessing memory:segmenting and paging,as well as the process of converting logical address to linear address and mapping virtual address to physical address. Througn segmenting and paging mechanism,we can realize the independent address space for every process in multi_process system,as well as the measure for protecting the system memory which can prevent the system breakup caused by illegal memory access.