[U-Boot] Initial environment variables

[Mike Frysinger]

On Thursday 16 July 2009 17:08:55 Ben Warren wrote:
> Ron Madrid wrote:
> > --- On Thu, 7/16/09, Mike Frysinger <vapier at gentoo.org> wrote:
> >> the board maintainer decides the default env values, not
> >> board users.  Ben's
> >> comment was probably on the assumption that you are in the
> >> latter category.
> >
> > Ah, that could be why.  Thankfully I am the maintainer for the board.  So
> > I am going to assume then that it would be OK for me to add these
> > variable settings to my board's include/configs file and submit a patch
> > for it, unless I here other objections.
>
> No, there should be no default net parameters, because you're making
> likely-bogus assumptions about the network that your board's going to go
> into.  Just because your LAN uses '192.168.0.x' doesn't mean anybody
> else's does.

i dont see why this is a problem.  providing a consistent default network 
setup doesnt cause any problems whatsoever.  if you have a different network 
layout, then it's trivial to (1) change it or (2) type "dhcp".

this is the first ive heard against letting board maintainers dictate default 
network settings.  i do it for all ADI Blackfin boards and never once have i 
heard a complaint from people who use them.

> It's even worse for MAC addresses - what if I buy two of
> your boards and plug them into the same switch?  If the addresses are
> identical all sorts of bad things can happen.  Not to mention that
> public MAC addresses are assigned (and paid for) and should be
> guaranteed to be unique.  And private (bit 41 set) addresses are used in
> many different ways.  One systems company that I worked at would program
> these dynamically based on which shelf/slot the board was plugged into.
> It's best to fail loudly (a printf stating that MAC addresses haven't
> been programmed) than to silently cause network issues.

MAC addresses are a completely different issue than IP settings.  i agree that 
there should never be a default environment value in any board in the tree.  a 
quick grep of the tree indicates that people have been very bad in this area 
(and i see that i merged two such Blackfin boards).  i'll send patches for the 
two boards i watch over.
-mike
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