Writing Device Drivers

System Topology

To identify where a fault might have occurred, diagnosis engines need to have the topology for a given software or hardware system represented. The fmd(1M) daemon provides diagnosis engines with a handle to a topology snapshot that can be used during diagnosis. Topology information is used to represent the resource, ASRU, and FRU found in each fault event. The topology can also be used to store the platform label, FRUID, and serial number identification.

The resource payload member in the fault event is always represented by the physical path location from the platform chassis outward. For example, a PCI controller function that is bridged from the main system bus to a PCI local bus is represented by its hc scheme path name:


The ASRU payload member in the fault event is typically represented by the Solaris device tree instance name that is bound to a hardware controller, device, or function. FMA uses the dev scheme to represent the ASRU in its native format for actions that might be taken by a future implementation of a retire agent specifically designed for I/O devices:


The FRU payload representation in the fault event varies depending on the closest replaceable component to the I/O resource that has been diagnosed as faulty. For example, a fault event for a broken embedded PCI controller might name the motherboard of the system as the FRU that needs to be replaced:


The label payload is a string that gives the location of the FRU in the same form as it is printed on the chassis or motherboard, for example next to a DIMM slot or PCI card slot:

Label: SLOT 2