Browse Prior Art Database

Method to Provide Coprocessor Access to System Memory in a Virtual Memory System

IP.com Disclosure Number: IPCOM000061703D
Original Publication Date: 1986-Sep-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 2 page(s) / 41K

Publishing Venue

IBM

Related People

O'Quin, JT: AUTHOR

Abstract

The figure illustrates schematically a virtual memory system in which a Coprocessor is attached to the I/O bus which, in turn, is connected to system memory through an Input/Output Channel Controller (IOCC). A method is described in which the Coprocessor is allowed access to system memory in such a way as to allow both Coprocessor applications and processor applications the capability of concurrent execution out of system memory. In accordance with the this method, the Virtual Resource Manager (VRM) creates a segment at system initialization and segment register 14 is reserved for this segment. The first 16M bytes of this segment provide the processor or Coprocessor access to any system memory allocated to the Coprocessor.

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Method to Provide Coprocessor Access to System Memory in a Virtual Memory System

The figure illustrates schematically a virtual memory system in which a Coprocessor is attached to the I/O bus which, in turn, is connected to system memory through an Input/Output Channel Controller (IOCC). A method is described in which the Coprocessor is allowed access to system memory in such a way as to allow both Coprocessor applications and processor applications the capability of concurrent execution out of system memory. In accordance with the this method, the Virtual Resource Manager (VRM) creates a segment at system initialization and segment register 14 is reserved for this segment. The first 16M bytes of this segment provide the processor or Coprocessor access to any system memory allocated to the Coprocessor. The VRM service, referred to as $MAPSYS, allocates page frames to this segment, assigns the frames the appropriate address, and initializes the IOCC to allow Coprocessor access to this memory. Reserving segment register 14 allows both the Coprocessor and the processor applications the capability of concurrent operation. Executing Coprocessor applications out of system memory allows for lower machine cost since it is not necessary to buy bus memory for Coprocessor applications. Device drivers executing in the Coprocessor that use first party Direct Memory Access (DMA) need to be able to perform DMA operations to the Coprocessor address space in system memories. Thes...