Intel® System Debugger - System Debug User and Reference Guide
User and Reference Guide
Debugging System Management Mode
System Management Mode (SMM) is a special-purpose operating mode provided for handling system-wide functions like power management, system hardware control, or proprietary OEM-designed code. It is intended for use only by system firmware, not by applications software or general-purpose systems software. The main benefit of SMM is that it offers a distinct and easily isolated processor environment that operates transparently to the operating system or executive and software applications.