root=/dev/nfs on sbc8260

[jtm at smoothsmoothie.com]

On Thu, Dec 13, 2001 at 10:41:40AM -0500, Andrew Dixon wrote:
>
> Here is something very strange.  In PPCBoot I set the ethernet address
> to 00:a0:1e:90:15:55.
>
> ....
>
> Now, as I watch Linux try to come up I see the following:
>
> ....
>
> Has anyone else seen this before?

In the ethernet driver for the FCC, it changes the MAC address based on
the FCC number.h

In a standard 2.4.4 kernel, arch/ppc/8260_io/fcc_enet.c is the
following code (around line 1315):
       /* Set Ethernet station address.
         *
         * This is supplied in the board information structure, so we
         * copy that into the controller.
         * So, far we have only been given one Ethernet address. We make
         * it unique by setting a few bits in the upper byte of the
         * non-static part of the address.
         */
        eap = (unsigned char *)&(ep->fen_paddrh);
        for (i=5; i>=0; i--) {
                if (i == 3) {
                        dev->dev_addr[i] = bd->bi_enetaddr[i];
                        dev->dev_addr[i] |= (1 << (7 - fip->fc_fccnum));
                        *eap++ = dev->dev_addr[i];
                }
                else {
                        *eap++ = dev->dev_addr[i] = bd->bi_enetaddr[i];
                }
        }


You can here see that the ethernet port's MAC address is dependent on
the fcc number.

--
Jay Monkman	    The truth knocks on the door and you say "Go away, I'm
monkman at jump.net    looking for the truth," and so it goes away. Puzzling.
		     - from _Zen_and_the_Art_of_Motorcycle_Maintenance_

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