Critical Issue
If you enable local loopback on the MAC functions’s MII, GMII, or RGMII, the Quartus II software displays the following warning messages when you compile the designs:
Critical Warning: "mixed_port_feed_through_mode" parameter
of RAM atom altera_tse_mac:altera_tse_mac_inst|altera_tse_top_gen_host:top_gen_host_inst|altera_tse_top_w_fifo_10_100_1000:U_MAC_TOP|altera_tse_loopback_ff:U_LBFF|altera_tse_a_fifo_24:U_LBFF|altera_tse_sdpm_altsyncram:U_RAM|altsyncram:altsyncram_component|altsyncram_o4e1:auto_generated|ram_block1a8 cannot
have value "old" when different read and write clocks are used.
Critical Warning: "mixed_port_feed_through_mode" parameter of RAM
atom altera_tse_mac:altera_tse_mac_inst|altera_tse_top_gen_host:top_gen_host_inst|altera_tse_top_w_fifo_10_100_1000:U_MAC_TOP|altera_tse_loopback_ff:U_LBFF|altera_tse_a_fifo_24:U_LBFF|altera_tse_sdpm_altsyncram:U_RAM|altsyncram:altsyncram_component|altsyncram_o4e1:auto_generated|ram_block1a7 cannot
have value "old" when different read and write clocks are used.
You may safely ignore the warning messages.
This issue affects all designs with local loopback enabled on the MAC’s MII, GMII or RGMII.
No workaround.This issue will be fixed in a future version of the Triple-Speed Ethernet MegaCore function.