How to change MAC address on RPI-B?

[John W. Kitz]

Ian,

On Sat, 2016-11-26 at 00:07 +0100, diffusae wrote:
> Hi John,
> 
> On 25.11.2016 20:56, John W. Kitz wrote:
> 
> > 
> > So when doing so the locally administered MAC address is passed on 
> > from uEnv.txt to the O/S during boot and is then used to override 
> > the globally
> I didn't think, that it will be passed from the U-Boot Enviroment 
> settings. You can set the MAC address, but the FreeBSD kernel shows 
> always the unique MAC address.
> 
> > 
> > unique MAC address or does the O/S check both the information found 
> > in its configuration files and what is configured in uEnv.txt before 
> > configuring and activating the network interface(s)?
> Which configuration files do you mean? AFAIK there is only the FDT 
> blob.
> I guess it ignores the setting in uEnv.txt.
> 
> > 
> > Makes me wonder which of the two (i.e. locally administered through 
> > uEnv.txt or locally administered through the O/S) takes precedence.
> Only the unique MAC address and the locally administered MAC address, 
> will take affect.
> 
> > 
> > In addition this might affect configuration decisions when one would 
> > want to configure a device for net booting (at least when browsing 
> > through what can be configured by means of uEnv.txt I believe that 
> > was one of the options I
> > saw) through uEnv.txt?
> Personally, I like u-boot. It has various options, runs on a lot of 
> devices and it's also nice to handle.
> 
> Best regards,
> _

I looked into this tonight, and there is some code missing in u-boot to
handle passing a mac address set in the u-boot environment into the kernel
via the fdt data.

It would be pretty simple to fix.  We need to add an ethernet0 alias
pointing to the /axi/usb/hub/ethernet node to our rpi dts, and the attached
patch needs to replace the current one in the u-boot-rpi port.

This lets you set usbethaddr in the u-boot environment (via uEnv.txt or
saved directly using saveenv), and it will get used by both u-boot and
freebsd.

Having gotten it this far, I don't really have time right now to get the
patch committed to ports.  Hopefully somebody else can help with that.

JKi: I was just curious, but have no immediate use for the features
discussed in this particular thread at this time. So please don't make the
effort to get mentioned changes implemented because of this thread.