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Self Mapping for a Variably Configured Nucleus

IP.com Disclosure Number: IPCOM000079715D
Original Publication Date: 1973-Aug-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 30K

Publishing Venue

IBM

Related People

Brannon, TL: AUTHOR

Abstract

The location of the control sections (CSECTS) in the nucleus of a virtual storage control program cannot be predetermined, if the configuration of that nucleus is dependent upon factors which are variable at the time of nucleus initialization. For example, the addresses of pageable nucleus CSECTs (located in the high end of the virtual address space) depend upon the size of the virtual address space, which can be changed during nucleus initialization. This program, when included as part of the nucleus data set, provides a map of CSECT names and addresses which can be optionally generated during the initialization process. The map is available shortly after the final CSECT locations are determined and before the reconfiguration actually takes place.

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Self Mapping for a Variably Configured Nucleus

The location of the control sections (CSECTS) in the nucleus of a virtual storage control program cannot be predetermined, if the configuration of that nucleus is dependent upon factors which are variable at the time of nucleus initialization. For example, the addresses of pageable nucleus CSECTs (located in the high end of the virtual address space) depend upon the size of the virtual address space, which can be changed during nucleus initialization. This program, when included as part of the nucleus data set, provides a map of CSECT names and addresses which can be optionally generated during the initialization process. The map is available shortly after the final CSECT locations are determined and before the reconfiguration actually takes place. Therefore, the code and data necessary to provide the map can be excluded from the final nucleus configuration, eliminating any requirement for permanent storage space.

Map data entries consist of an eight-byte character representation of the CSECT name, and a four-byte address constant (ADCON). The fact that the ADCONs are relocatable expressions is the basis of the self-mapping concept. The figure shows how the mapping program fits into the nucleus initialization process. After the nucleus is loaded into real storage, the final configuration is determined and recorded by setting address assignments in an address table which has one entry for each CSECT. Various factors m...