The Unabridged Pentium 4 IA32 Processor Genealogy

The Spurious Interrupt Vector

The Problem

Assume that an interrupt is detected on the LINT0 input and, as a result, the Local APIC generates an interrupt to the processor. Also assume that, at this moment, the processor may raise its task priority (see “Task and Processor Priority” on page 1551) to be >= the level of the interrupt for which the processor is being interrupted. In the interval between the dispatch of the interrupt to the processor core and the core requesting the vector from the Local APIC, software may have masked that particular interrupt. What vector will the Local APIC supply to the processor core?

The Solution

In the scenario just described, the Local APIC delivers a spurious interrupt vector to the processor core. Refer to ...