MAC fixed

Hi,
i read a lot of documentazion on internet but there isn’t a clear answer…

I have two serial on my beagleboard eth0 and eth1 that works well.

Now:

  1. I must set a two fixed mac address on uEnv.txt, HOW?
  2. I need that the two interface are ready after boot (now i must make an ifcongi ethx up) . How?

Thank you in advance