14.3.11. Ethernet does not work in Linux

Question:

Ethernet does not work on my board. But everything is fine when I use the ethernet interface in U-Boot (for example by performing a TFTP download). This is a bug in U-Boot, right?

Answer:

No. It's a bug in the Linux ethernet driver.

In some cases the Linux driver fails to set the MAC address. That's a buggy driver then - Linux ethernet drivers are supposed to read the MAC address at startup. On ->open, they are supposed to reprogram the MAC address back into the chip (but not the EEPROM, if any) whether or not the address has been changed.

In general, a Linux driver shall not make any assumptions about any initialization being done (or not done) by a boot loader; instead, that driver is responsible for performing all of the necessary initialization itself.

And U-Boot shall not touch any hardware it does not access itself. If you don't use the ethernet interface in U-Boot, it won't be initialized by U-Boot.

A pretty extensive discussion of this issue can be found in the thread ATAG for MAC address on the ARM Linux mailing list. archive 1 archive 2