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Dynamic Linkage Between Modules of a Stand Alone Program in a Virtual Storage Environment

IP.com Disclosure Number: IPCOM000079848D
Original Publication Date: 1973-Sep-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Kern, RM: AUTHOR [+2]

Abstract

Programs fetched by an operating system for execution are relocated by the operating system, to the virtual address which has been assigned to the program. In a stand-alone environment, this relocation must also be performed. However, if the program is to execute in a virtual environment where the virtual storage address to which it is to be relocated is unknown, when the program is loaded, the relocation must take place dynamically at execution time.

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Dynamic Linkage Between Modules of a Stand Alone Program in a Virtual Storage Environment

Programs fetched by an operating system for execution are relocated by the operating system, to the virtual address which has been assigned to the program. In a stand-alone environment, this relocation must also be performed. However, if the program is to execute in a virtual environment where the virtual storage address to which it is to be relocated is unknown, when the program is loaded, the relocation must take place dynamically at execution time.

When individual modules making up the stand-alone program are assembled, relocation is performed within each module by the assembler relative to the beginning of the module. When individual modules are combined to form the complete stand-alone program, relocation relative to some known load point may be done for the entire program by the program performing the combination. Following the combination, the location of each module is known to the other modules only relative to the load point. The virtual storage location of each module remains unknown. Therefore, direct module linkage in a virtual environment is difficult.

Linkage in the virtual environment may be performed by a centralized linkage supervisor, which does not execute in a virtual environment. The virtual storage location to be associated with the beginning of the stand-alone program may be determined by the linkage supervisor. This location, when added to the locati...