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Interrupt Layout

The interrupt layout is determined by information in the device tree. An interrupt tree overlays the other information in the device tree to describe how the interrupts are configured. The Trampoline code traverses this device tree interrupt tree and builds data structures that are used to dispatch interrupts. The device tree interrupt tree is defined in the Open Firmware Recommended Practice: Interrupt Mapping . It is not necessary to change any of the interrupt dispatching code, either 68K or native. All the necessary information is retrieved from the device tree.

This interrupt dispatch code has drastically reduced latency times as compared to all previous PCI Macintosh computers.