root@ATK-IMX6U:~# ifconfig eth0 down
root@ATK-IMX6U:~# ifconfig eth0 up
/soc/aips-bus@02000000/ethernet@020b4000: could not find phandle
SIOCSIFFLAGS: No such device
root@ATK-IMX6U:~# ifconfig eth1 down
root@ATK-IMX6U:~# IPv6: ADDRCONF(NETDEV_UP): eth1: link is not ready
root@ATK-IMX6U:~# ifconfig eth1 up
fec 2188000.ethernet eth1: Freescale FEC PHY driver [SMSC LAN8710/LAN8720] (mii_bus:phy_addr=20b4000.ethernet:00, irq=-1)
root@ATK-IMX6U:~#
root@ATK-IMX6U:~# IPv6: ADDRCONF(NETDEV_UP): eth1: link is not ready
fec 2188000.ethernet eth1: Link is Up - 100Mbps/Full - flow control rx/tx
IPv6: ADDRCONF(NETDEV_CHANGE): eth1: link becomes ready