[coreboot - Bug #579] (New) MAC address programmed by coreboot to onboard RTL8111F does not persist

[Keith Hui]

Issue #579 has been reported by Keith Hui.

----------------------------------------
Bug #579: MAC address programmed by coreboot to onboard RTL8111F does not persist
https://ticket.coreboot.org/issues/579

* Author: Keith Hui
* Status: New
* Priority: Normal
* Category: chipset configuration
* Target version: none
* Start date: 2025-03-01
* Related links: https://review.coreboot.org/c/coreboot/+/86172
* Affected hardware: Asus P8Z77-V LE PLUS w/ RTL8111F
* Affected OS: Linux kernel 6.12.7
----------------------------------------
I am producing a coreboot port on Asus P8Z77-V LE PLUS on which this issue is observed. It has a RTL8111F ethernet controller without EEPROM for vital product data.

I enabled the rtl8168 driver in coreboot so I can configure the LEDs and MAC address. Lights work great, but the MAC address always revert to `00:00:00:00:00:05` by the Linux r8169 kernel module. I would then have to reassign its proper MAC address using `ip link change eno0 address <mac>`.

The device appears to be taking the address I programmed, but r8169 reverts it both on init and teardown, insisting that `00:00:00:00:00:05` is its permanent MAC address.

Survival of coreboot programmed MAC address before r8169 driver is confirmed by a debug read back I inserted in the coreboot rtl81xx driver, as well as by temporarily blacklisting r8169.

Vendor firmware is unaffected.