Executive Overview - Compaq 108164-003 - ProLiant - 800 Integration Notes

PCI Bus Numbering in a Microsoft Windows NT Environment

Executive Overview

The term Peripheral Component Interconnect, commonly known as PCI, refers to the bus
architecture standard. The PCI bus technology has become an industry standard; today's servers
provide a large number of expansion slots and can be populated with a greater number of PCI
disk and network controllers. PCI buses provide fast access between controllers and/or system
memory and the host processor. PCI buses offer a significant performance advantage over EISA
buses.
The PCI Special Interest Group (SIG) is an unincorporated association of members of the
microcomputer industry set up for the purpose of monitoring and enhancing the development of
the PCI architecture. The PCI Steering Committee is a group of nine companies that oversees SIG
activities and reviews formal recommendations for changes to PCI Specification(s). Compaq is a
member of the SIG Steering Committee and actively proposes and contributes new design
functions for future revisions to the PCI Specification.
Later in this document, examples
are provided in two test scenarios,
illustrating what happens to PCI
bus numbering when configuration
changes occur.
during system start up. Windows NT uses these numbers to identify bridged controllers. If
controllers are added to an existing system, the PCI bus numbering might change. This change
might affect the operation of your system.
This white paper provides information to help systems professionals understand how the PCI
Specification addresses server bus numbering assignments. This document discusses:
How the PCI BIOS detects and numbers PCI buses and bridges.
What happens to PCI Bus numbering at each system start up.
How adding or removing PCI devices might cause a renumbering of PCI buses.
How Windows NT handles bus numbering in the Windows NT Registry.
How to prevent PCI bus numbering mismatches from occurring.
This document contains several examples to demonstrate PCI bus numbering. After reading this
document, you should be able to properly configure and/or reconfigure a Windows NT system when
PCI bus numbers are reassigned with minimal interruption to the network.
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PCI bus technology development continues to advance at a rapid pace to
meet customer's business requirements. Server technology includes
equipment, such as the ProLiant 8000 with multiple PCI buses. The
computing capabilities of these servers can be further expanded through
PCI controllers and PCI bridged devices such as the Smart Array 4250ES
Controller. Each PCI bus in the system is numbered by the PCI BIOS
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