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Configuration Tasks

Macintosh Open Firmware code performs the following tasks to help the PCI system support the devices previously found by the Open Firmware startup process:

• It programs certain configuration bits in the 64-byte standard PCI header portion of PCI configuration space.
• It determines the resource requirements (memory and I/O space) of each device, based on the device's reg property. The reg property is created either by executing the FCode in the card's expansion ROM, or if FCode is not present, the system Open Firmware code creates a reg property for the device by querying the device's PCI configuration base registers.
• After accumulating the resource requirements for all devices in the system, the system Open Firmware code constructs a conflict-free address map and adds the resulting assigned-addresses property to each PCI device's node in the device tree.