sis630 mac address

Ronald G Minnich rminnich at
Sun Sep 22 11:56:29 CEST 2002

On Sat, 21 Sep 2002, Steve M. Gehlbach wrote:

> My pcchips m787cl+ with the sis630e chipset started reporting a 00:00..00
> mac address.  It was working at first, but somewhere in the process of
> debugging I started getting all zeros.

I am pretty sure you won't find an eeprom. PC chips has a habit of storing
MAC address in CMOS to save the eeprom cost on the motherboard. Matsonic
ms7308e does this too. At some point your cmos probably got zerod. Bad
thing the vendors do is store MAC address in cmos. Zero cmos, zero mac

They copy the MAC address from flash to cmos if cmos is 0. The idea is, if
cmos is 0, the BIOS copies the MAC address from CMOS to flash. If the cmos
is 0 not, the BIOS doesn't do anything. Thus, MAC address is stored in
BOTH flash and CMOS.

That's why they tell you to NEVER interrupt a BIOS update ... you can lose
the MAC address. This amazingly fragile scheme is becoming more and more

It is becoming clear that we need a cmos.c for each mainboard, which does
the mainboard-specific cmos functions. too bad.

> The bios that came with the board does not seem to have a way to set it
> either.

That makes sense. Part of the flash upgrade (from what I have seen) is to
load the MAC from CMOS to BIOS ... no MAC in CMOS, no MAC address in

> BTW, I have the text mode vga going on this mobo if anyone is interested in
> the code.  I was able to use my stpc vga code with only a few changes.

Very interesting, how does it fit in to linuxbios? Is it
mainboard-independent or ...


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