For information, I've come to flash 6 kirkwood (3 dockstar and 3 GoflexNet) with default archlinux uboot: pacman -S uboot-dockstar|goflexnet
On one of them, the ethaddr was flashed as: mvNetConfig XX:XX:XX:XX:XX:XX instead of XX:XX:XX:XX:XX:XX (MAC address).
So I have used an asix USB to Ethernet key
$this->bbcode_second_pass_code('', 'lsusb
Bus 001 Device 004: ID 0b95:1790 ASIX Electronics Corp. AX88179 Gigabit Ethernet')
On the alarm boot USB key, I had just to copy /etc/systemd/network/eth0.network to /etc/systemd/network/eth1.network and edit the file as:
$this->bbcode_second_pass_code('', 'Name=eth1
[Network]
DHCP=yes')
Then I defined the USB to Ethernet key MAC address in my dhcp server (get the MAC address by ip link on another computer)
Reboot with only a net cable plugged in the USB to Ethernet key and voilà.
I could ssh to the Dockstar and redefine properly the embeded eth0 ethaddr parameter with fw_setenv ethaddr 'go:od:ma:ca:dd:re'