Browse Prior Art Database

Sharing Read-Only Memory among Multiple Logical Partitions

IP.com Disclosure Number: IPCOM000104145D
Original Publication Date: 1993-Mar-01
Included in the Prior Art Database: 2005-Mar-18
Document File: 2 page(s) / 54K

Publishing Venue

IBM

Related People

Marron, A: AUTHOR

Abstract

Disclosed is a method for sharing real memory between logical partition is a PR/SM environment.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 53% of the total text.

Sharing Read-Only Memory among Multiple Logical Partitions

      Disclosed is a method for sharing real memory between logical
partition is a PR/SM environment.

      When multiple copies of an operating system run in logical
partitions under PR/SM, it is desirable to share some of the memory
allocated to the operating systems.

      In addition to the segment and page table which control virtual
address mapping, the hardware has an additional level of indirection
to REAL memory addressing.  This indirection provides for flexible
memory reconfiguration between partitions.

      For purposes of this disclosure a SEGMENT is the most granular
unit of reconfiguration and real address indirection (Also called
"subincrement").  This segment may or may not be related to the
concept of segment in virtual storage management.

      This capability is used for memory sharing in the following
manner:

1.  A system running in a logical partition optionally places some
    "read-only" data in fixed areas in real storage, which are fully
    contained in segments.  Such data can be portions of the nucleus
    (kernel) of the system, other object modules, or read-only
    tables.  In addition to the actual data, directories and indices
    which list the objects to be shared, are imbedded in fixed
    locations inside the segment at hand.

2.  The system then optionally issues a hardware command or signal,
    requesting "MAKE THIS SEGMENT SHARABLE AND READ ONLY".

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