Technical Q&A HW 59 - Why did the name of the PCI bridge change? (29-Mar-99) Q: Why did the name of the PCI bridge change from Bandit or Grackle to a generic name such as pci? A: Name is a PCI device property that tells the Open Firmware and its client, say, the Mac OS, the name of a node in the device tree. When the first Macintosh with Open Firmware (the Power Macintosh 9500) was introduced, the concept of generic names was not part of the Open Firmware bindings. Apple gave the name of Bandit to the PCI bridge. But what was Bandit? No one knew except engineers working on the 9500. This presented a bad situation, so the concept of generic names was introduced. For a PCI bridge between the host bus and the PCI bus the generic name was pci. This presented yet another bad dilemma: what to do with the devices already in use? If a driver was looking for a node name of Bandit, it would not find it since it had been changed to pci. So the compatible property was used to store the old name of Bandit while the name property had the generic name. The boot ROM code was changed to search first on the name property. If that failed, the next step was to search the compatible property. A developer should always search using the boot ROMs algorithm just described. -- Wayne Flansburg Worldwide Developer Technical Support Technical Q&As | Contents Previous Question | Next Question To contact us, please use the Contact Us page. |