Technical Q&A HW61

The AAPL, slot-name property and PCI

Q: I have a PCI device and use the AAPL,slot-name property in my code because it is geographically determined, as opposed to dynamically determined. (I did this because that is how it was done for NuBus devices.) My PCI device worked correctly until recently, but now my driver is broken. What happened?

A: The property AAPL,slot-name is a user interface property which should be used to inform your user that your card in slot "XX" needs to be removed, repaired, etc. It's designed to help the user locate a card after opening the computer's case.

The slot-name value such as "XX" will match one of the names given by the computer's design team to the slots. These names are typically silk-screened on the main motherboard next to the slot. In the past, the slots have had names like A1, B2, etc.; on the 1999 (blue and white) Power Macintosh G3, the slots are named J9 through J12.

In other words, AAPL,slot-name contains an abstract name that is only to be used for user interface reasons--not to be used by software to reference or identify your card in any other way. In fact, the property will probably be different on different machines, and the property will also be different when your card is placed in an expansion chassis.

Do not use this property for any reason other than informing the user how to locate the slot that contains your device.

As an aside, IEEE 1275 does not require any property name to start with AAPL. Any property name that starts with AAPL,... is an Apple-defined property. (AAPL is Apple's four character stock symbol, which is guaranteed to be an organizationally unique identifier (OUI) as described in Designing PCI Cards and Drivers.)