The device methods for an adapter card are essentially the same as for any other device. They need to perform roughly the same tasks as those described in "Writing a Device Method" in AIX Kernel Extensions and Device Support Programming Concepts. However, there is one additional important consideration. The Bus Configure method, or Bus Configurator, is responsible for discovering the adapter cards present in the system and for assigning bus resources to each of the adapters. These resources include interrupt levels, DMA arbitration levels, bus memory, and bus I/O space.
Adapters are typically defined and configured at boot time. However, if an adapter is not configured due to unresolvable bus resource conflicts, or if an adapter is unconfigured at run time with the rmdev command, an attempt to configure an adapter at run time may occur.
If an attempt is made, the Configure method for the adapter must take these steps to ensure system integrity:
Additional guidelines must be followed when adding support for a new adapter card. They are discussed in:
ODM Device Configuration Object Classes.
The rmdev command.
Understanding Direct Memory Access (DMA), Understanding Interrupts in AIX Kernel Extensions and Device Support Programming Concepts.