METHOD FOR SAVING AND RESTORING THE STATE OF A CPU EXECUTING CODE IN PROTECTED MODE

摘要

A method of saving and restoring the state of a CPU operating code in protected mode on a computer system. The save method makes use of BIOS operating in shadow RAM located in a region where linear addresses equal physical addresses while saving the state of the CPU. The registers that cannot be directly saved to memory are determined by searching the system memory for data structures that correspond to the particular register. The restore method uses dummy page tables that point to the shadowed BIOS to allow the CPU to reenter protected mode without generating a protection fault.