Learn about context switching on Arm Cortex

在这个过程中，操作系统会保存上一个进程的执行状态，然后恢复下一个进程的执行状态，这个过程这称为context switch， 那么context switch的过程中，都保存和恢复了哪些东西呢，如下所示：

We will discuss how the hardware was designed to support this operation, features that impact the context switching implementation such as the Floating Point Unit (FPU), and common pitfalls seen when porting an RTOS to a platform.

This example demonstrates simple real-time kernel context switching operations between two threads using MPU regions that are available in Arm Cortex-M processors.

This is an introductory topic for software developers who would like to learn about context switching operations on Cortex-M processors in a bare-metal environment.

Basically save the registers for one context, and restore the registers/state of a prior context and continue running. call it context, thread, task, whatever you want from a higher level programmers perspective

曾經我對 PendSV 中斷的存在意義感到疑惑，比如說，為什麼我們不能像 mini-arm-os 一樣在 systick_handler 裡面進行 Context Switch 呢？