Intel Corporation

Doug Moran

Kenneth C Creta

D Michael Bell

David W Archer

Steve Pawlowski

Vasudevan Shanmugasundaram

Methods and apparatus for inbound PCI configuration cycles are disclosed. By definition, PCI bridges block upstream progress of configuration cycles initiated by a PCI bus master on their secondary buses. In the described embodiments, a PCI bus master can execute a configuration cycle despite this limitation, by converting the configuration cycle command to Memory Read and Write commands that a PCI bridge will forward upstream. The PCI bus master writes the address of a target configuration register to a first predefined address, and pushes or pulls data from that target register by subsequently initiating a memory access to a second predefined address. A platform chipset is designed to recognize Memory Read and Write accesses to the predefined addresses as relating to an inbound configuration cycle. When a memory access to the second address is received, the chipset uses the information stored at the first address to form and execute a configuration cycle on behalf of the downstream PCI bus master.

Mechanism for PCI I/O-initiated configuration cycles

A computer system includes a host processor coupled to a host bus. A bridge controller is coupled to the host bus and to a plurality of first buses. The computer system also includes one or more bus bridges, each coupled to the bridge controller via one or more of said first buses. Each bus bridge is connected to one or more second buses. Either the first buses or the second buses are each configurable in either an independent mode in which the bus operates independently, or a combined mode in which two or more of said first buses or said second buses are combined to create a single bus.

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Folsom, CA, United States of America

Doug Moran