sonic-buildimage/device/quanta/x86_64-quanta_ix7_bwde-r0/Quanta-IX7-BWDE-32X/platform-def.json

{
    "fec-mode": {
        "Ethernet0-127": {
            "1": {
                 "10000":  [ "none", "fc" ],
                 "25000":  [ "none", "rs" ]
            },
            "2": {
                 "20000":  [ "none", "fc" ],
                 "50000":  [ "none", "rs" ]
            },
            "4": {
                 "40000":  [ "none", "fc" ],
                 "100000": [ "none", "rs" ]
            }
        }
    },
    "default-fec-mode": {
        "Ethernet0-127": {
            "4": {
                 "40000":  "none",
                 "100000": "rs"
            }
        }
    },
    "native-port-supported-speeds": {
        "Ethernet0-127": {
            "4": ["100000","40000"]
        }        
    }
}