Browse Prior Art Database

Method to Bound Peripheral Component Interconnect System Configurations

IP.com Disclosure Number: IPCOM000113933D
Original Publication Date: 1994-Oct-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 54K

Publishing Venue

IBM

Related People

Merkin, CM: AUTHOR

Abstract

Disclosed is a data structure which may be programmed into the Read Only Memory (ROM) of a system to describe the organization of the Peripheral Component Interconnect (PCI) bus for the system. In the absence of such a data structure, the PCI architecture provides for up to 256 separate busses, each of which can have up to 32 separate devices. Furthermore, each device can have up to eight functions, providing for up to 65,536 individual functions. Thus, if bounds are not provided, the time required by system software to determine the configuration of a system is expected to be unsatisfactory.

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Method to Bound Peripheral Component Interconnect System Configurations

      Disclosed is a data structure which may be programmed into the
Read Only Memory (ROM) of a system to describe the organization of
the Peripheral Component Interconnect (PCI) bus for the system.  In
the absence of such a data structure, the PCI architecture provides
for up to 256 separate busses, each of which can have up to 32
separate devices.  Furthermore, each device can have up to eight
functions, providing for up to 65,536 individual functions.  Thus, if
bounds are not provided, the time required by system software to
determine the configuration of a system is expected to be
unsatisfactory.

      The data structure providing bounds for the system is an array
of information defining the PCI location of each device directly
attached to the system board and the PCI location of each connector
through which a board may be added.  Specifically, for each device in
the system, a PCI bus number, a device number, a function number, and
a system slot number, which defines where the device resides, is
defined.  If the system slot number is zero, the device is directly
attached to the system (planar) board.  The PCI vendor ID and device
ID define which device is present.  If the vendor ID value is 0FFFFh.
the entry is associated with a socket into which an additional board
is added.  Also, any system-specific PCI connection information,
which may be required to configure the device, such...