Linux 0.12: Task Switching 条件

1.  The current task executes a JMP or CALL that refers to a TSS  descriptor.

2.  The current task executes a JMP or CALL that refers to a task gate.

3.  An interrupt or exception vectors to a task gate in the IDT.

4.  The current task executes an IRET when the NT flag is set.

To cause a task switch, a JMP or CALL instruction can refer either to a TSS descriptor or to a task gate.

The effect is the same in either case: the 80386 switches to the indicated task

也就是说，想要发生任务切换，就要去访问TSS描述符 或者 访问 任务门。 这个任务门可以放到 IDT中。