config return values

The config callout may return zero or more of the following flags:

Normally, an interrupt is masked off until a routine attaches to it via InterruptAttach() or InterruptAttachEvent(). If CPU fault indications are routed through to a hardware interrupt (not recommended!), the interrupt would, by default, be disabled. Setting this flag causes a "dummy" connection to be made to this source, causing this level to become unmasked.
Prevents user code from attaching to this interrupt level. Generally used with INTR_CONFIG_FLAG_PREATTACH, but could be used to prevent user code from attaching to any interrupt in general.
Identifies the vector that's used as the target of an inter-processor interrupt in an SMP system.