User guide

84 www.xilinx.com Virtex-5 FPGA Integrated Endpoint Block
UG197 (v1.5) July 22, 2009
Chapter 4: Integrated Endpoint Block Operation
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Access to Unimplemented Configuration Space
According to PCI Express Specification 1.1, an Endpoint should treat access to an
unimplemented configuration space as an unsupported request. The integrated Endpoint
block responds with a successful completion that is non-compliant.
Workaround
There are no workarounds for this issue. However, as an upstream component is not
expected to access an unimplemented configuration space, this has no impact on safe
operation.
No workarounds are implemented in LogiCORE Endpoint Block Plus or LogiCORE
Endpoint Block for PCI Express Designs.
Receive TLPs with Illegal Payload Length
According to PCI Express Specification 1.1, any TLP with a payload length that is not a
multiple of 1DW is illegal. The integrated Endpoint block does not send an ERR_FATAL
message when it receives a TLP with an illegal payload length. Instead, the block detects
this TLP as a bad LCRC and sends back a NAK.
Workaround
There are no workarounds for this issue. However, such an occurrence is very rare.
No workarounds are implemented in LogiCORE Endpoint Block Plus or LogiCORE
Endpoint Block for PCI Express Designs.
Receiving PM_PME or PME_TO_Ack Messages
According to PCI Express Specification 1.1, an Endpoint should not receive a PM_PME or
a PME_TO_Ack message. If it receives such a message, it should respond by sending an
ERR_NON_FATAL message. The integrated Endpoint block does not respond with any
error message and silently drops the received messages.
Workaround
There are no workarounds for this issue. However, this issue is expected to have minimal
or no impact on safe operation.
No workarounds are implemented in LogiCORE Endpoint Block Plus or LogiCORE
Endpoint Block for PCI Express Designs.
Loopback Slave Mode Considerations
The integrated Endpoint block supports Loopback Slave mode operation as described in
the PCI Express Base Specification 1.1. When the integrated Endpoint block is operating as
a Loopback slave, all data received is looped back to the upstream component. The
upstream component can initiate an exit from Loopback by transmitting an Electrical Idle
ordered set followed by transitioning the serial lines to Electrical Idle. The integrated
Endpoint block is expected to loopback all data including the Electrical Idle ordered set
before transitioning its TX serial line to Electrical Idle. The block does not loopback all data.