Altera Cyclone V User Manual page 115

Chapter 10: Interrupts
Interrupts for Root Ports
Normally, the Root Port services rather than sends interrupts; however, in two
circumstances the Root Port can send an interrupt to itself to record error conditions:
When the AER option is enabled, the aer_msi_num[4:0] signal indicates which
■
MSI is being sent to the root complex when an error is logged in the AER
Capability structure. This mechanism is an alternative to using the serr_out
signal. The aer_msi_num[4:0] is only used for Root Ports and you must set it to a
constant value. It cannot toggle during operation.
■ If the Root Port detects a Power Management Event, the pex_msi_num[4:0] signal
is used by Power Management or Hot Plug to determine the offset between the
base message interrupt number and the message interrupt number to send
through MSI. The user must set pex_msi_num[4:0]to a fixed value.
The Root Error Status register reports the status of error messages. The Root Error
Status register is part of the PCI Express AER Extended Capability structure. It is
located at offset 0x830 of the Configuration Space registers.
November 2011 Altera Corporation
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