Impact of the x86 System Management Mode in Real-Time Systems

There is a tendency toward the use of personal computers (PC) in real-time systems. These computers have highprocessing capacity and reduced costs when compared to software and hardware development fordedicated platforms. However, real-time systems require latency predictability and the processors of the x86architecture have aspecial protection and correction mode known as SystemManagement Mode (SMM). This mode is not traceable by the operating system and it can cause unpredictability in thesystem. This article describes the SMM, presents tools and methods for its detection and an analysis of its impacton real-time systems.