Message Signaled Interrupts (MSI)

General

The PCI spec permits a PCI function to generate an interrupt in one of three ways:

  • The method defined in the earlier versions of the PCI spec required the PCI function to assert an interrupt pin. The pin is tied to a trace that delivers the interrupt request to an input on the interrupt controller.

  • The later versions of the PCI spec defined the Message Signaled Interrupt (MSI) method.

  • The 3.0 PCI spec defined the MSI-X method.

The MSI and MSI-X methods are also supported in PCI-X and in PCI Express. In order to support the MSI method, an adapter must implement the following PCI configuration registers:

  • The MSI Address register.

  • The MSI Data register.

  • The MSI Control register.

In order to support the MSI-X ...

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