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Providing Addressability for New Address Space

IP.com Disclosure Number: IPCOM000079382D
Original Publication Date: 1973-Jun-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Brinck, GM: AUTHOR [+3]

Abstract

Providing Addressability for a New Virtual Address Space Dynamic creation of new virtual address spaces in a multiple virtual memory environment creates an unusual programming problem, if the translation tables for the new address space are to be virtually addressable only in the new space. The technique described herein allows a host address space (memory) to create a new memory easily, and without changing from virtual to real-addressing mode.

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Providing Addressability for New Address Space

Providing Addressability for a New Virtual Address Space Dynamic creation of new virtual address spaces in a multiple virtual memory environment creates an unusual programming problem, if the translation tables for the new address space are to be virtually addressable only in the new space. The technique described herein allows a host address space (memory) to create a new memory easily, and without changing from virtual to real-addressing mode.

The amount of space necessary to contain the minimum hardware and software control information required for an address space, is calculated and rounded up to a multiple of the virtual-page size. This amount of space is obtained in the host memory and backed with real storage, thus providing addressability to the area. Skeleton translation tables are placed in the area by copying those parts of the host's tables that are the same as the new memory's, and initializing the balance of the table entries to unused status.

Next, the virtual address at which the new memory's control information will reside is decided and the corresponding entries in the skeleton tables are initialized, to point to the same real storage that is being used to back the area being set up in the host memory. This has the effect of making the area common, i.e., addressable, to both memories although via different virtual addresses. Since all the addresses stored into the area so far have been real addresses, they are independent of which memory is addressing the area. To make the new memory usable to the software System Co...