On Wed, 2009-03-11 at 06:23 -0700, David Miller wrote:
quoted text
> From: Wolfgang Denk <wd@denx.de>
> Date: Wed, 11 Mar 2009 10:09:38 +0100
> 
> > How do you then handle situations where this is impossible? Say, when
> > the firmware cannot write to those registers for example because  the
> > ethernet  controller is not even powered on (to reduce power consump-
> > tion), but will get powered on only in Linux  when  the  driver  gets
> > loaded (i. e. on demand only, not always)?
> 
> That's what NVRAM, CMOS, EEPROM's and other writable long-term
> storage areas are for.
> 
> To be quite honest with you, any ethernet device that doesn't
> have an EEPROM where the chip instance's ethernet address is
> stored is completely broken.

Not having persistent MAC storage makes it quite hard from userspace to
tie specific network configuration to a specific device, because
(rightly so) kernel network interface names are *not* stable.  And since
most manufacturers don't bother to put serial numbers into things like
the USB descriptors, there is now way to uniquely identify if you plug
two in.  LOSE.

Save a kitten.  Add an EEPROM.

Dan


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