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AXI Bridge for PCI Express v2.4
58
PG055 June 4, 2014
Chapter 3:
Designing with the Core
Additional IP is required in the Endpoint PCIe system to create the prioritization scheme for
the MSI vectors on the PCIe interface.
Legacy Interrupts
The bridge supports legacy interrupts for PCI if selected by the C_INTERRUPT_PIN
parameter. (Can only be set to 1 when C_INCLUDE_RC = 0.) A value of 1 selects INTA, as
defined in
. If a legacy interrupt for PCI support is selected and the
msi_enable
output pin indicates that the bridge has endpoint MSI functionality disabled
(
MSI_enable
= ‘0’), the
intx_msi_request
pin is defined as
intx
. When the
intx
pin
goes High, an assert
INTA
message is sent. When the
INTX
pin goes Low, a deassert
INTA
message is sent. These messages are defined in the PCI 2.1 specification. The
intx_msi_request
pin input is valid only when the bridge is operating in Endpoint mode
(C_INCLUDE_RC=0).
Malformed TLP
The integrated block for PCI Express detects a malformed TLP. For the IP configured as an
Endpoint core, a malformed TLP results in a fatal error message being sent upstream if error
reporting is enabled in the Device Control Register.
For the IP configured as a Root Port, when a malformed TLP is received from the Endpoint,
this can fall under one of several types of violations as per the PCIe specification. For
example, if a Received TLP has the Error Poison bit set, this is discarded by the MM/S master
bridge, and the MEP (Master Error Poison) bit is set in the Interrupt Decode register.
Abnormal Conditions
This section describes how the Slave side (
) and Master side (
) of the AXI
Bridge for PCI Express core handle abnormal conditions.
Slave Bridge Abnormal Conditions
Slave Bridge abnormal conditions are classified as: Illegal Burst Type and Completion TLP
Errors. The following sections describe the manner in which the Bridge handles these errors.
110
Reserved
N/A
111
Reserved
N/A
Table 3-5:
MSI Vectors Enabled in Message Control Register
(Cont’d)
Value
Number of Messages Requested
Output Signal, MSI_Vector_Width (2:0)