There is a known issue with the XAUI PHY IP in which the port width of the "rx_recovered_clk" signal in the generated HDL from the MegaWizard™ is the incorrect width. The width is 3-bits wide when it should be 4.
This issue was introduced in Quartus® II v11.0 and v11.0sp1, but has been fixed as of v11.1. Affected devices include all Stratix® IV, Arria® II, Cyclone® IV, and HardCopy® IV variants that include transceivers.
A workaround for Quartus II v11.0 is to manually change the width to be 4 bits. This workaround is also valid for Qaurtus II v11.0sp1. However, a patch exists that can be applied to Quartus II v11.0sp1. This patch can be downloaded using the following links:
Quartus II software version 11.0SP1 patch 1.32 for Windows
Quartus II software version 11.0SP1 patch 1.32 for Linux