Intel
®
81341 and 81342—Address Translation Unit (PCI Express)
Intel
®
81341 and 81342 I/O Processors
Developer’s Manual
December 2007
238
Order Number: 315037-002US
3.2
PCI Express* Link Characteristics
The PCI Express** port supports x8, x4, x2, and x1 operation. Lane reversal and
polarity inversion automatically occur in an attempt to successfully train the link.
The PCI Express* port is configured to ease adapter card implementations. The lane
number and lane polarity should enable straight routing between the component and
the PCI Express* card edge connector. The lane reversal feature can be utilized to
simplify applications where this component is connected to the upstream device in a
planar fashion. For example integrating the device on a motherboard with direct
connection to the I/O Hub.
Supported Lane Reversal Modes
x8
7:0, 0:7
x4
3:0, 0:3
x2
1:0, 0:1
x1
0, 7
Port bifurcation is not supported. This component supports a single x8 PCI Express port
and can not be split into multiple x4 ports.
The PCI Express interface supports a maximum payload size of 512 Bytes and returns
completions with minimum of 128 byte payloads.