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Rendering Context Manager Exploiting the RISC/System 6000 IOCC

IP.com Disclosure Number: IPCOM000107708D
Original Publication Date: 1992-Mar-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 1 page(s) / 56K

Publishing Venue

IBM

Related People

Flurry, GA: AUTHOR [+2]

Abstract

Disclosed is an implementation of the Rendering Context Manager (RCM) that exploits the RISC System/6000* I/O Channel Controller (IOCC) (*) protection mechanisms to improve the performance of the RCM.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 60% of the total text.

Rendering Context Manager Exploiting the RISC/System 6000 IOCC

       Disclosed is an implementation of the Rendering Context
Manager (RCM) that exploits the RISC System/6000* I/O Channel
Controller (IOCC) (*) protection mechanisms to improve the
performance of the RCM.

      The Rendering Context Manager manages access to graphics
adapters by multiple graphics processes. To perform this function,
the RCM depends on the system hardware and software to provide a
means of authorizing access to a graphics adapter for individual
graphics processes, and to provide a means of detecting unauthorized
accesses of a graphics adapter by graphics processes, and finally a
means of invoking the RCM when unauthorized attempts (called graphics
faults) take place.  A standard technique uses the virtual storage
page tables to provide the protection required; the RCM can map
storage pages that correspond to an adapter into and out of the
address space of a graphics process; the normal page fault mechanism
can invoke the RCM in the case of a graphics fault.

      To use the I/O Channel Controller, the Rendering Context
Manager assigns a set of Translation Control Words (TCWs) to each
adapter, assigns a TCW protection key to each adapter, and finally
loads the TCWs for the adapter with the appropriate key. The RCM also
assigns the bit in the authority mask of Channel Status Register 15
(CSR15) that corresponds to the TCW protection key to an adapter.
Thus it is possible to autho...