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Publication No.
500-9300007876-000
Rev. C.0
System Resources, Memory Mapping, and Registers 81
7.3 Advanced Programmable Interrupt Controller
The XVR16 supports APIC. This handling of the APIC interrupt services must be
supported by the operating system. The I/O APIC handles interrupts differently
than the standard interrupt controller. These differences are:
• Method of Interrupt Transmission: The I/O APIC transmits interrupts
through processor FSB, and interrupts are handled without the need for the
processor to run an interrupt acknowledge cycle.
• Interrupt Priority: The priority of interrupts in the I/O APIC is independent
of the interrupt number. For example, interrupt 10 may be given a higher
priority than interrupt 3.
• More Interrupts: The three I/O APICs in the XVR16 support a total of
twenty-four independent interrupt sources.
7.4 Message Signaled Interrupts
The XVR16 supports Message Signaled Interrupts (MSI) on all of its PCIe links for
transporting interrupts from PCIe devices towards the CPU.