Writing Device Drivers

Response Agents

An agent is a software component that takes action in response to a diagnosis or repair. For example, the CPU and memory retire agent is designed to act on list.suspects that contain a fault.cpu.* event. The cpumem-retire agent will attempt to off-line a CPU or retire a physical memory page from service. If the agent is successful, an entry in the fault manager's ASRU cache is added for the page or CPU that was successfully retired. The fmadm(1M) utility, as shown in the example below, shows an entry for a memory rank that has been diagnosed as having a fault. ASRUs that the system does not have the ability to off-line, retire, or disable, will also have an entry in the ASRU cache, but they will be seen as degraded. Degraded means the resource associated with the ASRU is faulty, but the ASRU is unable to be removed from service. Currently Solaris agent software cannot act upon I/O ASRUs (device instances). All faulty I/O resource entries in the cache are in the degraded state.

# fmadm faulty
-------- ----------------------------------------------------------------------
degraded mem:///motherboard=0/chip=1/memory-controller=0/dimm=3/rank=0
-------- ----------------------------------------------------------------------

The primary purpose of a retire agent is to isolate (safely remove from service) the piece of hardware or software that has been diagnosed as faulty.

Agents can also take other important actions such as the following actions: