In the GFP v1.2 64-bit VHDL version of the loopback module, when configured for parallel hunting mode, the loopback module is incorrect. It might create an invalid data stream if EOF is followed on the next cycle by another EOF. In this case, the incorrect REM value is used for the second EOF. This issue does not affect the Verilog example design, and it does not affect designs that use either "idle only" or "no hunting".
You can fix this issue in the <component_name>/implement/vhdl/gfp_loopback.vhd module by changing the line number 199 from the following:
if (M_LINE_EOF_N = '0') then
to the following:
if (m_line_eof_n_d1 = '0') then
This issue will be fixed in the next GFP release, scheduled for Q1 2005.