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I have just bought a new motherboard, and all the expansion slots on it are PCI-Express. So, with the advent of message signalled interrupts, it occurs to me to wonder whether the APIC has a future as the chip through which ISA interrupts are routed, and little more besides. To put it another way, is the APIC about to become "legacy" before its time?

The (Local) APIC is the part of the processor handling the interrupts from built-in devices, IRQ lines, MSIs and other processors. Even if you remove IRQs as a source, it still handles all interrupts and you rendered only a minority of its functionality unused.

It won't go anywhere.

I assume you were talking about the IOAPIC instead (which is actually a dumb thing that converts interrupt lines to interrupt messages)?

Combuster wrote:The (Local) APIC is the part of the processor handling the interrupts from built-in devices, IRQ lines, MSIs and other processors. Even if you remove IRQs as a source, it still handles all interrupts and you rendered only a minority of its functionality unused.

It won't go anywhere.

I was thinking more of the i/o APIC. In spite of the similarity of their names, their functionality is very different.