Why do rx_st_err signal continues to drive an unknown value ('X') during Stratix V PCIe core simulation?

Description

Due to a bug in the Stratix V PCIe Hard IP core the rx_st_err signal is incorrectly assigned in the file "altpcie_sv_hip_ast_hwtcl.v".

Resolution

To workaround this issue open the file "altpcie_sv_hip_ast_hwtcl.v" then find and change the following line:
From:

   assign rx_st_err = |rx_st_err_int[3:0];

To:
   assign rx_st_err = rx_st_err_int[0];

This issue will be fixed in a future version of the Quartus® II software release.