Interrupt Service Threads (Compact 2013)
3/26/2014
When an interrupt service routine (ISR) notifies the kernel of a specific logical interrupt value, the kernel examines an internal table to map the logical interrupt value to an event handle. The kernel wakes the associated interrupt service thread (IST) by signaling the event. This event is a standard synchronization object that wakes a thread in response to an event.
The IST runs in a user mode process called the User Mode Driver Host. For more information about the User Mode Driver Host, see User Mode Driver Framework.
The IST performs the following tasks:
- Loads the ISR if the driver uses an installable ISR
- Creates an event, registers this event in the kernel for the logical interrupt identifier that is associated with the ISR, and waits for the event
- Performs all interrupt processing when it wakes on the event
Service Interrupts describes how the IST interacts with other interrupt handling components to service an interrupt.