Re: Getting a stable MAC address for a RPI CM3+ with ue0 interface

On Sep 25, 2023, at 10:10, Patrick M. Hausen <pmh@hausen.com> wrote:

>> Am 24.09.2023 um 23:05 schrieb Patrick M. Hausen <pmh@hausen.com>:
>> 
>> Hi all
>> 
>>> Am 23.09.2023 um 21:28 schrieb Ronald Klop <ronald@FreeBSD.org>:
>>> 
>>> Would this work?
>>> 
>>> diff --git a/sys/dev/usb/net/if_smsc.c b/sys/dev/usb/net/if_smsc.c
>>> index 0a0268bfa1a2..4a7983a20717 100644
>>> --- a/sys/dev/usb/net/if_smsc.c
>>> +++ b/sys/dev/usb/net/if_smsc.c
>>> [...]
>> 
>> After building and installing the kernel with this patch and reboot I
>> lost access to the node I used. I will try to set up console access
>> somehow ...
> 
> The development board I use for flashing etc. has got a serial port
> connector and even a USB to serial converter so you can just plug in
> USB to your laptop - I did not get any console output, though.
> 
> https://www.waveshare.com/wiki/Compute_Module_PoE_Board#Serial_port
> 
> I did get console output via HDMI, but my Apple keyboard seems not
> to work when plugged in to USB so I could not really examine what
> is wrong or boot into kernel.old - only diagonistic I can provide:
> 
> The new kernel prints the "No MAC address found" message, then panics.
> 
> I'm reflashing the module now ...
> 
> From reading your source code, what are you really trying to achieve?
> More diagnostic messages are a good thing, but from where are you
> trying to read that MAC address?
> 
> As far as I understand for the Pi you are supposed to use the RPi
> foundation OUI B8:27:EB plus the lower three octets of the Pi's
> serial number - regardless of the Ethernet adapter plugged in.

Definately not, in multiple ways.

0) Having multiple Ethernet adapters plugged in can all be used
   over the same time frame. The MAC addresses need to be distinct.

1) RPi4B's and the like are not set up to have such MAC addresses.
   Only older RPi*'s are.

> All Pis running Linux do this.

Quoting: https://www.raspberrypi.com/documentation/computers/remote-access.html#ethernet-mac-address

QUOTE
On Raspberry Pi 4 the MAC address is programmed at manufacture and there is no link between the MAC address and serial number. Both the MAC address and serial numbers are displayed on the bootloader HDMI diagnostics screen.
END QUOTE

I doubt that Linux overrides that.

I doubt that Linux is limited to having only one Ethernet
adapter present.

The USB3 Ethernet dongles that I have access to had their own
MAC addresses preset before I opened the packaging. I have
used such dongles on RPi2B v1.1, RPi2B v1.2, RPi3B, and
various RPi4B, both udner FreeBSD and under various vintages
of the official RPi* OS.

Perhaps you are referencing a much more limited/special
context.


===
Mark Millard
marklmi at yahoo.com