The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Feb. 16, 1999
Filed:
May. 03, 1996
Michael Seward Harvey, Hollis, NH (US);
Karen Lee Noel, Pembroke, NH (US);
Digital Equipment Corporation, Maynard, MA (US);
Abstract
A system for accessing page table entries is disclosed. The system provides access to a page table entry mapping a predetermined physical page of memory. The system includes a physical page data base having an entry for each physical page of memory. Each physical page data base entry contains backlink information regarding an associated physical page of memory. The present system obtains a physical page data base entry associated with the predetermined physical page of memory from the physical page data base. The system uses a reserved page table entry, for example mapped by shared space, to build a virtual window. The virtual window provides a virtual address that may be used to access the page table entry mapping the predetermined physical page of memory. The virtual address provided by the virtual window is mapped to physical memory by the reserved page table entry. In a further aspect of the invention, the present system determines whether the page table entry mapping the predetermined physical page of memory is accessible in the current process context. If the page table entry mapping the predetermined physical page of memory is not currently accessible, a virtual window is built using the reserved page table entry. If the page table entry mapping the predetermined physical page of memory is currently accessible, no virtual window is built. An organization of the page table into a tree structure is further disclosed.