2 System Board

Assigned Device Interrupts

 

Virtual wire mode: This mode is implemented with APIC controllers in the

 

ICH and P64H and used during boot time. The virtual wire mode allows the

 

transition to the “symmetric I/O mode”. In the virtual wire mode, only one

 

processor executes instructions.

 

Symmetric I/O mode: This mode is implemented with APIC controllers in

 

the ICH and P64H, and allows for multiple processor operations.

 

 

NOTE

In “PIC mode” and “virtual wire mode”, the PCI interrupts are routed to the

 

INT line. In the “symmetric I/O mode”, the PCI interrupts are routed to the

 

I/O APIC controllers and forwarded over an APIC bus to the processors.

 

 

PCI Interrupt Request Lines

PCI devices generate interrupt requests using up to four PCI interrupt request lines (INTA#, INTB#, INTC#, and INTD#).

PCI interrupts can be shared; several devices can use the same interrupt. However, optimal system performance is reached when minimizing the sharing of interrupts. Refer to page 68 for a table of the PCI device interrupts.

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