[coreboot] Gigabyte M57SLI-S4 MAC address

Fredrik Tolf fredrik at dolda2000.com
Sat May 17 05:48:49 CEST 2008

Hi list!

This mail is justa noteworthy observation I've made. I've got two
separate M57SLI-S4 motherboards on which I've installed Coreboot, and
I've noticed an interesting thing with the onboard Ethernet chip. It
seems it contains one MAC address in hardware, which is changed by the
factory-shipped BIOS during boot. The hardwired address begins with
00-E0-81, which seems to be registered to Tyan[1], and the address which
it is replaced with begins with 00-1D-7D, which seems to be registered
to Gigabyte. This is noteworthy for two reasons:

1. It confused me a lot at first. Since udev assigns a new interface
name for every MAC address it discovers, it made my DHCP client fail
since it couldn't find the interface it was configured for, so at first
I thought that Coreboot couldn't initialize the NIC. I got past that
pretty quickly, though.

2. More importantly, the hardwired address is actually the same for both
motherboards! More precisely, it is 00-E0-81-54-32-66. Thus, running
several of these board on the same physical link is a bad idea if one
does not change the address manually.

I don't know if anything should (or can) be done about this in Coreboot.
I just thought I'd mention it.

Fredrik Tolf

[1] <http://standards.ieee.org/regauth/oui/oui.txt>

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