International Business Machines Corporation

William H Schwartz

Richard Alan Dayan

James Franklin Macon, Jr

Scott G Kinnear

Douglas R Geisler

Suresh Yanamadala

A method and system for allowing multiple tasks to share virtual memory areas, in a memory management system for a computer, uses a data structure which maintains a list of address spaces shared by more than one task. For each entry in this list, a list of slots in virtual address space is maintained in the data structure, where each slot contains indications that said shared memory was mapped into a task. An offset table of directory pages is also maintained, and each entry in this directory points to a directory page for a task. The directory page entries for all of such directory pages points to a page table entry. An entry in each of the offset tables points to the entry in the list of shared address spaces for this set.

System and method for providing shared memory using shared virtual

A method and system for allowing multiple tasks to share virtual memory areas, in a memory management system for a computer, uses an independent address space created such that it can be 'attached' to multiple address spaces. Any change to the shared address space is reflected in all attached address spaces with just one operation to the shared address space. Entities in the shared address space require only one set of system resources. Since the same powerPC virtual segment ID is used for all attached address spaces, only one set of powerPC page table entries is needed. A feature is attaching shared memory with and without control privileges to provide protection; tasks with privilege can manipulate the address space using the same operations and base addresses as in the non-shared normal address space, and tasks with normal attachment can only reference the memory objects in the overlaid shared address space--memory objects can not be created or destroyed.

System and method for providing efficient shared memory in a virtual

A data processing system has a microprocessor, a memory system and a plurality of system devices the operation of which is controlled by BIOS routines. The BIOS routines are accessed through protected entry points. When an application program attempts to access one of the routines by using a hard coded instruction for jumping to such entry point, a BIOS signaling routine is executed which provides a signal to an operating system allowing the operating system to control the access without being bypassed.

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Delray Beach, FL, United States of America

William H Schwartz