Support random MAC address generation in AXI Ethernet driver

[venodela]

Summary

The AXI Ethernet driver(eth_xilinx_axienet.c) in Zephyr currently requires the local-mac-address property to be specified in the device tree. If it's not present, the driver fails to build due to the DT_INST_PROP(inst, local_mac_address) reference. This limits flexibility and requires each board/platform to provide a unique MAC manually, even during development and testing.

This enhancement proposes improving the AXI Ethernet driver to support random MAC address generation using Zephyr’s existing gen_random_mac() API if local-mac-address is not defined.

Describe the solution you'd like

Enhance the AXI Ethernet driver to detect if local-mac-address is missing from the device tree and generate a MAC address at runtime using Zephyr's gen_random_mac() function. The generated address should be stored in the driver’s runtime data structure and configured into the hardware as usual.

This change would eliminate the need for explicitly defining local-mac-address in all DT overlays, while still supporting it if present.

Driver file to update:
drivers/ethernet/eth_xilinx_axienet.c

[github-actions]

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[venodela]

FYI: @WorldofJARcraft

[maass-hamburg]

@venodela feel free to submit a PR implementing it. Take a look f.e. at the stm32_ethernet driver how to implement it.

[maass-hamburg]

a random address should only be used if zephyr,random-mac-address is set, a random address should not be a fallback if there is no other mac address.

[venodela]

@maass-hamburg Noted, i will plan to send the changes accordingly.

[venodela]

@maass-hamburg i sent a pull request for this enhancement : #92411