ARM processor operating mode

User mode

• User mode is the working mode of user program , Running in the user state of the operating system
• Do not have permission to access and operate other hardware resources , You can only process your own data
• Cannot switch to other modes , Except through the Soft interrupt perhaps abnormal

General interrupt mode

• Also called normal interrupt mode , Used to handle general interrupt requests , This mode is usually entered automatically after the hardware generates an interrupt signal
• This mode can freely access system hardware resources

management model

• CPU Default mode after power on , It is mainly used for system initialization
• Soft interrupt processing is also in this mode , When a user program in user mode requests to use hardware resources, it enters this mode through software interrupt

Mode switch

Software , External interrupt , abnormal Can change ARM The mode of operation of

abnormal

• The execution of instructions by the processor that results in the termination of the original program
• Exception handling cannot be nested

Anomalous source

Abnormal source and mode