Chapter 6: Control of External Interrupts

The external interrupt hardware is managed by a kernel-level device driver that is distributed with IRIX and automatically configured when the system supports external interrupts. The driver provides two abilities to user-level processes:

• the ability to change the state of an outgoing interrupt line, so as to interrupt the system to which the line is connected)

• the ability to capture an incoming interrupt signal with low latency

Note: Some software for external interrupt support is closely tied to the hardware of the system. The features described in this chapter are hardware-dependent and in many cases cannot be ported from one system type to another without making software changes. Beginning in IRIX 6.2, there is a hardware-independent way to capture incoming external interrupts: the user-level interrupt facility (ULI). To learn about ULI, see Chapter 7, "User-Level Interrupts," especially "Registering an External Interrupt Handler".

External Interrupts in Challenge and Onyx Systems