# Memory Protection in SMM

The SMM is an isolated execution environment according to Intel® 64 and IA-32 Architectures Software Developer’s Manual [IA32SDM]. The UEFI Platform Initialization [PI] specification volume 4 defines the SMM infrastructure. Figure 1 shows the SMM memory protection. RO designates read-only memory. XD designates execution-disabled memory.

Figure 1 - SMRAM memory protection