Magic SysRq Key

Introduction

Excerpt from Linux's Documentation/sysreq.txt:
What is the magic SysRq key?

It is a 'magical' key combo you can hit which the kernel will respond to regardless of whatever else it is doing, unless it is completely locked up.

Usage

• Check it is enabled:

# cat /proc/sys/kernel/sysrq 
1

From Host serial console with Kermit

• Send break character (Ctrl-\ b) then the key corresponding to the wanted action. For example to reset the board you will press:

Ctrl+AltGr+8 then b then b

From any terminal on the APF

• Send the character to corresponding /proc interface. For example to reset the board:

# echo b > /proc/sysrq-trigger

From the LCD pseudo terminal with an USB keyboard

• To Be Tested...