[U-Boot-Users] MAC address question...

Ladislav Michl ladis at linux-mips.org
Thu Aug 26 19:10:27 CEST 2004

On Thu, Aug 26, 2004 at 06:44:10PM +0200, Wolfgang Denk wrote:
> No. For U-Boot the reference is always the  value  of  the  "ethaddr"
> envrionment variable.

Ah, I probably didn't explain it too well :( "ethaddr" envrionment
variable still exist, but it's not stored together with other variables,
but in smc's eeprom itself (so it's not stored in two different places)

That feature is configurable (eeprom is optional and smc can be told not
to use it). Are you interested in patch?

> > allow U-Boot and (for example) Linux to boot with different mac address?
> > Why?
> Normally no user is supposed to touch  or  modify  the  MAC  address.
> That's why it's value in the default configuration is read-only after
> being  set.  It  gets set once during production (or automagically at
> first boot) and then never changes.

My point is exactly the same. After board is manufactured, it is put
into automatic tester which writes mac address (basicaly it is computer
hooked to serial line and some other signals for diagnostic) by issuing
setenv ethaddr command. This command stores mac address directly into
eeprom, not into the same space as other variables are stored (NOR

> Now _if_ you configure U-Boot to allow overwriting the setting,  then
> you  are  supposed  to know what you are doing, and we will not limit
> you. You may have a special purpose of doing  exactly  this.  If  you
> don't like this, then don't do it.

Once set, overwriting mac address is allowed, but it is password protected.
That way unexperienced user is not able to change it, but service
technician is.

> "UNIX was not designed to stop you from doing stupid things,  because
> that would also stop you from doing clever things."       - Doug Gwyn



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