language-agnostic - 是否必须有模式切换才能有资格作为上下文切换？

Question

是否必须有模式切换，即来自 user mode至 kernel mode为了将 Action 称为 context switch ?

Answer 1

不是。并不是所有的处理器都有 privilege levels .

上下文切换通常意味着从 Process Control Block 恢复执行状态.然而，上下文的概念是实现定义的。来自 Wikipedia :

What constitutes the context is determined by the processor and the operating system.
...
When a transition between user mode and kernel mode is required in an operating system, a context switch is not necessary; a mode transition is not by itself a context switch. However, depending on the operating system, a context switch may also take place at this time.