root@phyCORE-iMX31:~ ifconfig eth0|grep HWaddr
eth0      Link encap:Ethernet  HWaddr 2E:3B:47:69:3F:14  
root@phyCORE-iMX31:~ ifconfig eth0 down; ifconfig eth0 hw ether 00:50:C2:80:A8:33; ifconfig eth0 up
root@phyCORE-iMX31:~ ifconfig eth0|grep HWaddr
eth0      Link encap:Ethernet  HWaddr 8A:EF:AD:DC:5C:53  
root@phyCORE-iMX31:~ ifconfig eth0 down; ifconfig eth0 hw ether 00:50:C2:80:A8:33; ifconfig eth0 up
root@phyCORE-iMX31:~ ifconfig eth0|grep HWaddr
eth0      Link encap:Ethernet  HWaddr 2E:28:11:22:2D:EF  
root@phyCORE-iMX31:~ ifconfig eth0 down; ifconfig eth0 hw ether 00:50:C2:80:A8:33; ifconfig eth0 up
root@phyCORE-iMX31:~ ifconfig eth0|grep HWaddr
eth0      Link encap:Ethernet  HWaddr 5A:55:2B:DA:08:20  
root@phyCORE-iMX31:~ dmesg|tail
eth0: link down
eth0: link up, 100Mbps, full-duplex, lpa 0x45E1
eth0: SMSC911x/921x identified at 0xc7060000, IRQ: 129
eth0: SMSC911x MAC Address: 2e:28:11:22:2d:ef
eth0: link down
eth0: link up, 100Mbps, full-duplex, lpa 0x45E1
eth0: SMSC911x/921x identified at 0xc7060000, IRQ: 129
eth0: SMSC911x MAC Address: 5a:55:2b:da:08:20
eth0: link down
eth0: link up, 100Mbps, full-duplex, lpa 0x45E1