+local function swdev_from_board_json()
+ local boardinfo = jsc.parse(nfs.readfile("/etc/board.json") or "")
+ if type(boardinfo) == "table" and type(boardinfo.network) == "table" then
+ local net, val
+ for net, val in pairs(boardinfo.network) do
+ if type(val) == "table" and type(val.ifname) == "string" and
+ val.create_vlan == true
+ then
+ return val.ifname
+ end
+ end
+ end
+ return nil
+end
+