Why can't I create a Qsys Avalon BFM testbench of my Ethernet System?

Description

In the Quartus®  II software tool version 11.0sp1 it is not possible to generate an Avalon®  BFM Qsys testbench for the Triple-Speed Ethernet core when configured as 10/100 Small MAC or 1000 Small MAC. The following error occurs during generation:

Validation of the system failed

There were errors creating the testbench system

This issue can be resolved with the following workaround:

1. Open your current Qsys project
2. Double-click on the Triple Speed Ethernet controller and change the core variation to 10/100/1000 Ethernet MAC and click Finish. Save the project.
3. Click on the generation tab, and select the following options:
   Create simulation model: None
   Create testbench Qsys System: Standard BFMs for standard Avalon Interfaces
   Create testbench simulation model: None
   
   Then Click generate. This will produce another Qsys project containing BFM models for each of the interfaces.
4. Double-click on the tse_mac_0 and change back the core variation to it's original setting.
5. In the generation tab, set "Create testbench Qsys system" to none. This will avoid accedentally overwriting the testbench qsys system that is about to be modified. Save the project.
6. Open the generated Qsys project. This will be in the /testbench directory of your project.  When the project opens, there will be a number of errors (6) regarding missing signals. These are for the GMII part of the ethernet interface, this is a difference for the 10/100/1000 Ethernet MAC core compared to the Small MAC.
7. Open the conduit BFM core that is connected to the ethernet output, and remove the 6 GM_ signals that are not used by the Small MAC implementation. Save the project
8. In the generation tab, ensure the simulation model is set to "Verilog", no setting for "create testbench Qsys system", and uncheck "Create HDL design files for synthesis" and "Create block symbol file"
9. Generate the system. This will create a correctly configured Avalon BFM testbench.

This error shall be resolved in the next version of the Quartus II tools