To access the RS-FEC only from the 100G Ethernet Hard IP, select the Enable RS-FEC Transcode Bypass option and also select the appropriate CMAC Core Selection from the RS-FEC Transcode Bypass tab.
In this mode, the RS-FEC IP present inside the 100G Ethernet Hard IP core can be accessed and used. In this case, the 100G Ethernet IP core and GT functionalities are not available, and the other tab options are disabled.
If you deselect the Enable RS-FEC Transcode Bypass option, the other tab options are enabled with the default values.