2. 计算机
  3. The following scenario applies to questions 30, 31, and 32. Operating systems have evolved and changed over the years. The earli

The following scenario applies to questions 30, 31, and 32. Operating systems have evolved and changed over the years. The earli

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问题 The following scenario applies to questions 30, 31, and 32.
Operating systems have evolved and changed over the years. The earlier operating systems were monolithic and did not segregate critical processes from noncritical processes. As time went on operating system vendors started to reduce the amount of programming code that ran in kernel mode. Only the absolutely necessary code ran in kernel mode, and the remaining operating system code ran in user mode. This architecture introduced performance issues, which required the operating system vendors to reduce the critical operating system functionality to microkernels and allow the remaining operating system functionality to run in client/server models within kernel mode.
Which of the following best describes the last architecture described in this scenario?
选项 A、Hybrid microkernel
B、Layered
C、Monolithic
D、Hardened and embedded
答案A
解析 A正确。混合式微内核体系结构是单片集成和微内核体系结构的综合。关键的操作系统功能是在微内核结构中执行的，而其他的功能则是由运行在内核模式中的客户端／服务器模型中执行的。这种体系结构考虑到关键操作系统功能在内核模式中运行，而不会遇到前面体系结构中的性能问题。
B不正确。因为分层的操作系统体系结构的重点在于将操作系统的功能构建成分层结构。这种体系结构并不关注什么在内核模式中运行，什么不在内核模式中运行。
C不正确。因为这个行业起始于单片集成的操作系统，并由此演变。单片集成的操作系统并不隔离特权进程与非特权进程，也不使用内核。MS—DOS就是单片集成的操作系统的例子。
D不正确。因为稳定的嵌入式操作系统不是主要的体系结构。术语“稳定”仅意味着安全，而“嵌入式”意味着将操作系统的功能削减成仅提供安装软件的硬件所需要的基本而必须的功能。手机和定制的硬件通常都拥有嵌入式操作系统。
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