[Letux-kernel] Udoo neo and Ethernet MAC address (letux-4.19)

H. Nikolaus Schaller hns at goldelico.com
Wed Mar 27 15:25:48 CET 2019

it is a while that I observed some trouble with the Ethernet IP
address of the Udoo neo.

It did apparently change each time I did boot the board.

Deeper analysis shows that the board also has a different
MAC address each time, so that the DHCP server assigns a
new IP address...

Now I found this in the dmesg:

[    1.310700] libphy: Fixed MDIO Bus: probed
[    1.318614] fec 2188000.ethernet: 2188000.ethernet supply phy not found, using dummy regulator
[    1.327631] fec 2188000.ethernet: Linked as a consumer to regulator.0
[    1.346678] fec 2188000.ethernet (unnamed net_device) (uninitialized): Invalid MAC address: 00:00:00:00:00:00
[    1.356794] fec 2188000.ethernet (unnamed net_device) (uninitialized): Using random MAC address: 82:a9:2a:b1:2b:37
[    1.368115] libphy: fec_enet_mii_bus: probed

The code that produces this message is:


So the MAC can either be set

by the cmdline: fec.macaddr=0x00,0x04,0x9f,0x01,0x30,0xe0
or by some FUSE (where I don't know if that exists on the Usoo neo / i.MX6)
or by device tree (which would be a bad idea to give all devices the same MAC address)

So what I don't know in detail is the U-Boot of the Udoo neo and if that one should
handle device specific MAC addresses.

makesd simply uses a variant of U-Boot that I did pull from a working SD card provided
by the Udoo neo makers.

Another option would be to add that to the /etc/network/interfaces so that the MAC
address is stored on the SD card (and can be kept different between boards). But that
is user-space code which would be unique to the Udoo neo and not needed for e.g.

Generally this topic is not urgent, but has to be addressed in the future.


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