Enable magic SysRq key over serial

configname: CONFIG_MAGIC_SYSRQ_SERIAL

Linux Kernel Configuration
└─>Kernel hacking
└─>Generic Kernel Debugging Instruments
└─>Enable magic SysRq key over serial
In linux kernel since version 3.10 (release Date: 2013-06-30)  
Many embedded boards have a disconnected TTL level serial which can
generate some garbage that can lead to spurious false sysrq detects.
This option allows you to decide whether you want to enable the
magic SysRq key.