At each startup, the MAC address of eth0 is changed randomly.
This problem was found on FriendlyArm NanoPi Neo v1.1 and v1.2 boards with Armbian using a 4.x kernel. We note that this problem does not exist when using a FriendlyCore image (Xenial with kernel 4.14.0).
Version of the kernel used in this tutorial:
Linux nanopineo 4.14.18-sunxi #2 SMP Sat Feb 10 19:46:30 CET 2018 armv7l GNU/Linux
For those who have no time to lose with explanations:
sudo armbian-config
We go in System then Freeze. Then:
git clone http://github.com/epsilonrt/armbian-nanopi-ethaddr-patch
cd armbian-nanopi-ethaddr-patch
cp /boot/boot.cmd .
patch -p1 < boot.cmd.patch
mkimage -C none -A arm -T script -d boot.cmd boot.scr
sudo mv /boot/boot.cmd /boot/boot.cmd.orig
sudo mv /boot/boot.scr /boot/boot.scr.orig
sudo cp boot.* /boot
sudo dtc -I dtb -O dts -o sun8i-h3-nanopi-neo.dts /boot/dtb/sun8i-h3-nanopi-neo.dtb
sudo patch -p1 < sun8i-h3-nanopi-neo.dts.patch
sudo dtc -I dts -O dtb -o sun8i-h3-nanopi-neo.dtb sun8i-h3-nanopi-neo.dts
sudo mv /boot/dtb/sun8i-h3-nanopi-neo.dtb /boot/dtb/sun8i-h3-nanopi-neo.dtb.orig
sudo cp sun8i-h3-nanopi-neo.dtb /boot/dtb
sudo reboot
In the kernel 4.x mainline, the ethernet card driver (dwmac-sun8i), returns a random MAC address. This is probably due to a bad integration of Device Tree in this driver. On the site [linux-sunxi] (http://linux-sunxi.org/Sun8i_emac) it says:
"This driver is mainline, but DT was reverted in 4.13-rc7. DT should be back soon."
This is what the boot kernel indicates (dmesg):
[ 10.889856] dwmac-sun8i 1c30000.ethernet eth0: device MAC address 1a:b2:4a:84:f7:fc
[ 10.890960] Generic PHY 0.1:01: attached PHY driver > [Generic PHY] (mii_bus:phy_addr=0.1:01, irq=POLL)
....
[ 14.009054] dwmac-sun8i 1c30000.ethernet eth0: Link is Up - 100Mbps/Full - flow control off
The boot program of nanopi (u-boot) has a variable ethaddr but not used by the kernel! This variable can be read by accessing the command line of u-boot. To do this, connect a serial-usb adapter to the UART0 (debug) connector of the NanoPi. At boot time, press the Space key, then use printenv:
printenv ethaddr
We must have an address starting with 02: 81
This solution is the reverse engineering of the BSP FriendlyArm.
u-boot uses the file /boot/boot.scr (start script), this file
is a "compiled" version of the /boot/boot.cmd file.
In the /boot/boot.cmd file of FriendlyArm, we can see the 2 lines below:
# setup MAC address
fdt set ethernet0 local-mac-address ${mac_node}
The purpose of the line with fdt is to pass the MAC address (local-mac-address) to the kernel through device tree. It refers to ethernet0 which is used to refer to the eth0 card.
In the sun8i-h3-nanopi-neo.dts file of FriendlyArm, we can see that ethernet0 is an alias of /soc/ethernet@1c30000. In the ethernet@1c30000 block, we can see a local-mac-address parameter:
status = "okay";
local-mac-address = [00 00 00 00 00 00];
Solution found !
You have to start by freezing the kernel and u-boot updates :
sudo armbian-config
We go in System then Freeze. If we want to check:
dpkg -l | grep ^hi
hi linux-dtb-next-sunxi 5.41 armhf Linux DTB, version 4.14.18-sunxi
hi linux-image-next-sunxi 5.41 armhf Linux kernel, version 4.14.18-sunxi
hi linux-stretch-root-next-nanopineo 5.41 armhf Armbian tweaks for stretch on nanopineo (next branch)
hi linux-u-boot-nanopineo-next 5.41 armhf Uboot loader 2017.11
We clone the repository :
git clone http://github.com/epsilonrt/armbian-nanopi-ethaddr-patch
cd armbian-nanopi-ethaddr-patch
Then we patch the u-boot script:
cp /boot/boot.cmd .
patch -p1 < boot.cmd.patch
mkimage -C none -A arm -T script -d boot.cmd boot.scr
sudo mv /boot/boot.cmd /boot/boot.cmd.orig
sudo mv /boot/boot.scr /boot/boot.scr.orig
sudo cp boot.* /boot
Then we decompile the device tree, pat it and recompile it:
sudo dtc -I dtb -O dts -o sun8i-h3-nanopi-neo.dts /boot/dtb/sun8i-h3-nanopi-neo.dtb
sudo patch -p1 < sun8i-h3-nanopi-neo.dts.patch
sudo dtc -I dts -O dtb -o sun8i-h3-nanopi-neo.dtb sun8i-h3-nanopi-neo.dts
sudo mv /boot/dtb/sun8i-h3-nanopi-neo.dtb /boot/dtb/sun8i-h3-nanopi-neo.dtb.orig
sudo cp sun8i-h3-nanopi-neo.dtb /boot/dtb
Do not take into account the warnings displayed by dtc.
Here ! It only remains to reboot:
sudo reboot
You just have to hope that the people in charge of the driver solve this problem one day ...