Method for saving and restoring the state of a CPU executing code in protected mode including estimating the value of the page table base register
US5577220A · kind A · utility
147Cited by
1References
5Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Oct 3, 1995 |
| Grant date | Nov 19, 1996 |
| Priority date | — |
| Expiry date | Oct 3, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F9/4418
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.