Interprocessor Interrupts

Windows NT requires the ability to send an interrupt from one processor to another, in order to get the attention of the target processor. Inter-processor interrupts (IPI) are the only interrupts one processor sends to another.

Ideally, the hardware allows sending an interprocessor interrupt to any one other processor, or any mask selected set of other processors, or all processors except the sender.

The inter-processor interrupt must be at a priority higher than any I/O device.