Cora Boards Set MAC address

[Marty Ryba]

Hi have a couple Cora boards I plan to have in a system together. I notice when they boot (same kernel image) they come up with the same Ethernet MAC address. Once the system is up I can temporarily change one using ifconfig, but that's not ideal. The Xilinx forum mentions that uboot gets the device part of the address from something in an I2C EEPROM, at least on some of their dev boards. Is there a process for doing similar to a Cora? The reference manual says something about a sticker, what am I supposed to do with that information? Do I have to create a different Petalinux build for each board (ugh!)?

 

[Marty Ryba]

I found the answer in the README.md for the PetaLinux build blob https://github.com/Digilent/Petalinux-Cora-Z7-07S, which I initially had ignored since I'm using 2022.1

Quote

The Cora Z7 does not have onboard non-volatile memory to store the MAC address in, so it must be set another way. A globally unique MAC is provided for each Cora Z7 on a sticker next to the Zynq-7000 chip. The system can be configured to use this address two ways: (1) by creating a file called uEnv.txt on the FAT partition of the microSD card that contains the following line (replacing x's with the MAC address):

ethaddr=xx:xx:xx:xx:xx:xx

BUT, I get this error:

U-Boot 2022.01 (Apr 04 2022 - 07:53:54 +0000)

CPU:   Zynq 7z007s
Silicon: v3.1
DRAM:  ECC disabled 512 MiB
Flash: 0 Bytes
NAND:  0 MiB
MMC:   mmc@e0100000: 0
Loading Environment from FAT... *** Error - No Valid Environment Area found
*** Warning - bad env area, using default environment

In:    serial@e0000000
Out:   serial@e0000000
Err:   serial@e0000000
Net:   
ZYNQ GEM: e000b000, mdio bus e000b000, phyaddr -1, interface rgmii-id
eth0: ethernet@e000b000
Hit any key to stop autoboot:  0 
switch to partitions #0, OK
mmc0 is current device
Scanning mmc 0:1...
Found U-Boot script /boot.scr
2776 bytes read in 13 ms (208 KiB/s)
## Executing script at 03000000
Trying to load boot images from mmc0
26 bytes read in 10 ms (2 KiB/s)
Importing environment(uEnv.txt) from mmc0...
## Error: Can't overwrite "ethaddr"
himport_r: can't insert "ethaddr=00:18:3E:04:2B:1C" into hash table

 

[Marty Ryba]

OK, so there's new security settings for u-boot. To get this to work, you have to run petalinux-config -c u-boot, then go to:

Environment->Enable overwriting environment

hit the space bar to enable environment overwrite by uEnv.txt