interrupt handler

- 5 steps of interrupt handler execution

content/OS/Interrupt/Interrupt Handler.md

@@ -7,18 +7,21 @@ tags:
   - OS
   - c
 Creation Date: 2023-11-20T20:40:44
-Last Date: 2024-04-27T21:28:15+08:00
+Last Date: 2025-01-30T23:35:03+08:00
 References: 
+description: An Interrupt Service Routine (ISR) manages interrupts by saving CPU state, handling tasks, invoking process scheduling, restoring CPU state, and returning. Use volatile for variables in C. The Interrupt Handler Pointer holds the memory address for ISR instructions.
 ---
 ## Abstract
 ---
 - Also known as **Interrupt Service Routine (ISR)**
 - A set of [[Instruction]] at a fixed address within [[Kernel]], responding to the [[Interrupts (中断)]] like [[System Call (系统调用)]] by performing the following 3 items
 
->[!important] 3 Steps
+>[!important] 5 Steps
 > 1. [[interrupt_handler_saving_state.png|Saves the state of the CPU]] for the [[Process (进程)]] into the process's [[Process Control Block (PCB)]]. The [[Register#Program Counter]] of the process is saved to a different [[Register]]. So the interrupted process can be resumed later
 > 2. Does its other business
 > 3. Invokes the [[Process Scheduling#Process Scheduler]]
+> 4. Restore register/CPU 
+> 5. Return from interrupt
 
 
 >[!caution] C Implementation