HyperTransport Bridges Uses PCI Configuration

HyperTransport bridges use the PCI configuration method and the 256 byte configuration space to set up and manage one primary bus and one or more secondary buses. The primary and secondary interfaces of a HyperTransport bridge may both be HyperTransport, or either one could bridge to another PCI-compatible protocol such as PCI or PCI-X. Because the configuration header contains bits to manage two different interfaces, there are two things to keep in mind when describing bridges between HyperTransport and another protocol:

1. For the HyperTransport interface, the meaning of some bits in the configuration header depends upon the particular interface (primary or secondary) that is implemented as HyperTransport.

2. For the interface that is not HyperTransport, bit field definitions revert back to the bus protocol being supported (e.g. PCI or PCI-X).