OK6410A development board (eight) 64 linux-5.11 OK6410A linux exception analysis

In ARM, exception A is a hardware concept. 

In Linux, exception B is a software concept

Linux exception classification 

Whether the arm exception is used

yes

Some of them take advantage of arm exceptions

Page fault exception

no

Some are not used

Division by 0 exception

Can users feel

yes

Some abnormal users can feel

Division by 0 exception

no

Some can't feel

Page fault exception

Which space is abnormal?

User Space

The application code caused an exception and an error

Kernel Space

Kernel code caused an exception and an error occurred

Are exceptions necessarily errors?

yes

When using the floating point software library, a division by zero exception occurs

no

Page fault exception

When using vfp, a division by zero exception occurs

Linux does not correspond to exception A in arm one by one, as shown below

Page fault exception

Division by 0 exception

But in most cases, in arm-linux, exception B in linux is implemented by exception A in arm

The exception in the application space is caused by the application code, and an error occurs. The kernel will help the process dump // so that we can use the dump file to debug the program

The exception in kernel space is caused by the kernel code, and an error occurs. At this time, the kernel generally helps us debug in the following ways

1. Print oops, but no panic // In this way, we can view the complete information through dmesg

2. Print oops and panic  // At this point we only have oops and panic information to view

// This sometimes causes loss of scene

// There are the following means to automatically save the scene

// 1. kdump

// 2. pstore