Intel
®
81341 and 81342 I/O Processors
December 2007
Developer’s Manual
Order Number: 315037-002US
743
Interrupt Controller Unit—Intel
®
81341 and 81342
11.3.4
Software Requirements For Exception Handling
To use the processor’s exception handling facilities, user software must provide the
following items in memory:
• Exception Handler Routines
• Software handler to nest certain exceptions (i.e., FIQ and IRQ)
These items are established in memory as part of the initialization procedure.
11.3.4.1 Nesting FIQ and IRQ Exceptions
Hardware does not provide support for nesting of any particular exception, including
the FIQ and IRQ exceptions.
In order to provide support for nested interrupts, a software handler must be provided
to save the Link Register (R14) and the SPSR (Saved Program Status Register) before
reenabling the FIQ or IRQ exception.