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Difference between IO-APIC and PCI-MSI-X

In the /proc/interruptsfile I see the IO-APIC level (or edge), and in another system I see PCI-MSI-X. Both have the same device. I do not get the difference between the two. Can I change PCI-MSI-X to IO-APIC ?? Which kernel module or conf or proc file or file does it belong to?

Is it safe to propagate interrupts to all available CPU cores?

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MSI-X interrupts are message-based interrupts and are the only method available for PCIe devices to signal interrupts. Instead of approving a hardware line for an interrupt signal, the device writes one word to a preconfigured address. This address is either a control register in the CPU, or a register in the root port of the PCIe, which emulates an outdated interrupt system. You see both of these cases.

The BIOS configures the board to send its MSI traps to the root port, which emulates INTx traps that enter the CPU through routing in APIC. When the OS supports MSI directly, the device driver can reprogram the MSI destination address so that the interrupt message directly goes to the CPU interrupt registers.

MSI-X MSI ( , , TX RX).

MSI , INTx, INTx PCIe, , , . " MSI-X ".

:

http://lwn.net/Articles/44139/

http://en.wikipedia.org/wiki/Message_Signaled_Interrupts

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