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School of Computer Science & Engineering
University of New South Wales
 Advanced Operating Systems 
 COMP9242 2002/S2 

Interrupts and Interrupt Handlers

• Each hardware interrupt is modelled as a virtual (hardware) thread.
• (At most) one user-level interrupt-handler thread is associated with each hardware interrupt.
• If an interrupt occurs, the kernel generates an IPC from the interrupt thread to the interrupt handler.
• The interrupt handler is in general (part of) a device driver.
  • It will need access to device registers.
  • This is done via a special mapping protocol of the root pager (covered later).

The kernel handles some interrupts internally (timer interrupt).