Dual-Mode Operation两状态运行 Sharing system resources requires operating system to ensure that an incorrect program cannot cause other programs to execute incorrectly. 共享系统资源要求操作系统确保有误程序不会引起其他程序的运行错误 Provide hardware support to differentiate between at least two modes of operations 至少在两个运行状态之间提供硬件支持 1. User mode-execution done on behalf of a user 用户态-代表用户执行完毕 2. Monitor mode(also supervisor mode or system mode execution done on behalf of operating system 管态(特权模式或系统模式)代表操作系统执行完毕 Applied Operating System Concepts 2.16Applied Operating System Concepts 2.16 Dual-Mode Operation两状态运行 • Sharing system resources requires operating system to ensure that an incorrect program cannot cause other programs to execute incorrectly. 共享系统资源要求操作系统确保有误程序不会引起其他程序的运行错误 • Provide hardware support to differentiate between at least two modes of operations. 至少在两个运行状态之间提供硬件支持 1. User mode – execution done on behalf of a user. 用户态-代表用户执行完毕 2. Monitor mode (also supervisor mode or system mode) – execution done on behalf of operating system. 管态（特权模式或系统模式）-代表操作系统执行完毕