sis630 mac address

Steve M. Gehlbach steve at
Mon Sep 23 00:43:00 CEST 2002

> This is probably because the MAC address in flash is 0 too. Consider a
> flash update. You have to:
> - write the new flash
> - write "permanent" parameters from CMOS to flash
> then, next time CMOS gets wiped, you copy the MAC etc. from FLASH to CMOS.
> If you load linuxbios and then zero flash, boom! -- no record of the MAC
> address of the board. If you then load the original flash, it will copy
> the all-zero mac address to flash.
> we're going to need a way to record this kind of nonsense in FLASH images
> of linuxbios.

Hmm... well I never touched the original flash BIOS.  I use an EMP-30 and
program different chips to test and run linuxbios.  I guess I thought the
mac would be in the original bios flash, and I  guess I don't understand how
it got changed.  The board came with the cmos jumper in the "clear"
position, which threw me since it wouldn't come up at first until I spotted

Anyway, the user space program to set a new MAC address in cmos is attached
to this email; it is pretty simple, but has to run as root of course.  Maybe
we should put this in linuxbios, as an option or something.  I wonder how
you pick a MAC address?  At one time they were assigned in blocks by
manufacturer, I thought.  I realize they only have to be unique on the
subnet, but if you start assigning them randomly and shipping them to
customers, what are the odds? Mathematically 1 in 2^48 but by Murphy
probably 1 in 2 of a collision :-/ .


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