Abstract: Two or more distinct operating systems (OSs) are loaded simultaneously and run on an x86 computer system. Each OS is booted serially and in such a way that the OS resides in a separate memory footprint than the other OSs by partitioning the memory map. The partition of the memory map includes a low memory region, dedicated memory partitions for storing each OS, and dedicated regions for storing shadows of the low memory region and the ACPI for each OS. Switching between the two or more resident OSs is performed by sleeping the current OS and then resuming the desired OS using the shadow previously stored for the desired OS. None of the resident OSs require any modification in order to run in this fashion.

Abstract: Firmware in a UEFI-compliant computing device is used to administer and alter a Secure Boot process for the computing device while continuing to provide protection from unauthorized third-party code.

Abstract: A mechanism for controlling the execution of Option ROM code on a Unified Extensible Firmware Interface (UEFI)-compliant computing device is discussed. A security policy enforced by the firmware may be configured by the computing platform designer/IT administrator to take different actions for different types of detected expansion cards or other devices due to the security characteristics of Option ROM drivers associated with the expansion card or device. The security policy may specify whether authorized signed UEFI Option ROM drivers, unauthorized but signed UEFI Option ROM drivers, unsigned UEFI Option ROM drivers and legacy Option ROM drivers are allowed to execute on the UEFI-compliant computing device.