How to handle USB CDC driver randomly assigned MAC

[test name <tuksgig gmail com>]

Hi,

I'm busy with a new embedded design, and I'd really like to use the
USB gadget CDC EEM driver for connectivity to the device. On the PC
side I get a random MAC address for the usb0 interface each time the
usbnet and cdc_eem driver is reloaded.

What would be the best way to handle this in NM? I want to use ipv4
link local addressing on the usb0 interface, but NM forgets this each
time the MAC is reset.

Teach usbnet/cdc_eem to give the same MAC every time?
Use udev/systemd to rename device based on USB VID/PID?
Handle locally assigned MACs differently in NM?