Altera Stratix V Avalon-ST - Manual (Page 127)

Interrupts
The Hard IP for PCI Express offers the following interrupt mechanisms:
• Message Signaled Interrupts (MSI)— MSI uses the Transaction Layer's request-acknowledge
handshaking protocol to implement interrupts. The MSI Capability structure is stored in the Configu‐
ration Space and is programmable using Configuration Space accesses. MSI interrupts are only
supported for Physical Functions.
• MSI-X—The Transaction Layer generates MSI-X messages which are single dword memory writes. In
contrast to the MSI capability structure, which contains all of the control and status information for
the interrupt vectors, the MSI-X Capability structure points to an MSI-X table structure and MSI-X
PBA structure which are stored in memory. MSI-X interrupts are supported for Physical and Virtual
Functions.
• Legacy interrupts—The
app_int_sts
port controls legacy interrupt generation. When
app_int_sts
is
asserted, the Hard IP generates an Assert_INT<n> message TLP.
• MSI interrupts are only supported for Physical Functions.
PIPE
The PIPE interface implements the Intel-designed PIPE interface specification. You can use this parallel
interface to speed simulation; however, you cannot use the PIPE interface in actual hardware.
• The Gen1, Gen2, and Gen3 simulation models support PIPE and serial simulation.
• For Gen3, the Altera BFM bypasses Gen3 Phase 2 and Phase 3 Equalization. However, Gen3 variants
can perform Phase 2 and Phase 3 equalization if instructed by a third-party BFM.
Related Information
PIPE Interface Signals on page 4-36
Data Link Layer
The Data Link Layer is located between the Transaction Layer and the Physical Layer. It maintains packet
integrity and communicates (by DLL packet transmission) at the PCI Express link level (as opposed to
component communication by TLP transmission in the interconnect fabric).
The DLL implements the following functions:
• Link management through the reception and transmission of DLL packets (DLLP), which are used for
the following functions:
• Power management of DLLP reception and transmission
• To transmit and receive
ACK
/
NACK
packets
• Data integrity through generation and checking of CRCs for TLPs and DLLPs
• TLP retransmission in case of
NAK
DLLP reception using the retry buffer
• Management of the retry buffer
• Link retraining requests in case of error through the Link Training and Status State Machine
(LTSSM) of the Physical Layer
UG-01097_sriov
2014.12.15
Interrupts 9-3
IP Core Architecture Altera Corporation
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