Notifier Chain
NuttX provides a callback list mechanism called Notifier Chain. Notifier chain is essentially a list of callbacks used at certain times, such as system asserting, powering off and restarting.
Notifier chain is very much like the Linux notifier chains, except for some implementation differences.
Classes of Notifier Chain
There are currently two different classes of notifier.
Atomic notifier chains
Atomic notifier chains: Chain callbacks run in interrupt/atomic context. In Nuttx, callouts are allowed to block(In Linux, callouts in atomic notifier chain are not allowed to block). One example of an Atomic notifier chain is turning off FPU when asserting.
Blocking notifier chains
Blocking notifier chains: Chain callbacks run in process context. Callouts are allowed to block. One example of a blocking notifier chain is when an orderly powering off is needed.
Common Notifier Chain Interfaces
Notifier Block Types
struct notifier_block. Defines one notifier callback entry.