Reads from this location return queued interrupt messages. Data from each read follows the format shown in Table: Root Port Interrupt FIFO Read Register 2 . For MSI interrupts, the message payload is presented in this register, while the header information is presented in the Root Port Interrupt FIFO Read 1 register. The interrupt-handling flow should be to read the Root Port Interrupt FIFO Read 1 register first, immediately followed by this register. For non-Root Port cores, reads return 0. For INTx interrupts, reads return zero.
Note: Reads are non-destructive. Removing the message from the FIFO requires a write to either this register or the Root Port Interrupt FIFO Read 1 register (write value is ignored).