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Browse Prior Art Database

Granular Reclaim of System Firmware Address Space

IP.com Disclosure Number: IPCOM000110576D
Original Publication Date: 1992-Dec-01
Included in the Prior Art Database: 2005-Mar-25
Document File: 1 page(s) / 37K

Publishing Venue

IBM

Related People

Bealkowski, R: AUTHOR

Abstract

This article describes a design and method for providing reclaim and reuse of address space within a computer system.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 93% of the total text.

Granular Reclaim of System Firmware Address Space

       This article describes a design and method for providing
reclaim and reuse of address space within a computer system.

      The power-on self-test (POST) and basic input output system
(BIOS) are the primary components of personal computer system
firmware.  This system firmware is stored in a non-volatile storage
device, such as read-only memory (ROM).  The ROM occupies address
space within the computer system.  In certain computer systems, this
system firmware address space is hex E0000 through hex FFFFF spanning
128 kilobytes.  The system firmware is not required to occupy the
entire 128 kilobytes.  It is desirable to reclaim address space not
used by the system firmware.

      The system firmware address space is first divided into a
number of smaller regions.  Defining 32 smaller regions of equal size
results in 4-kilobyte subregions.  A 32-bit control register is
defined with each bit position corresponding to one of the 4-kilobyte
subregions.  When the computer system is first powered on, each bit
in the control register defaults to the enabled state.  During the
execution of POST, POST determines which 4-kilobyte subregions are
not required by the system firmware.  Those subregions that are not
required are disabled by POST.  A subregion is disabled by
programming the subregion's corresponding bit position in the control
register to the disabled state.  Accesses to an enabled subregion...