In Lenovo systems, SMM BIOS Write Protection is used to prevent writes to SPI Flash. While this provides sufficient protection, an additional layer of protection is provided by SPI Protected Range Registers (PRx). After resuming from S3 sleep mode in various versions of BIOS for some Lenovo ThinkPad systems, the PRx is not set. This does not impact the SMM BIOS Write Protection, which keeps systems protected.