[U-Boot] Rescue /alternative boot

[Arno Steffen]

Dear Wolfgang Denk,

> Well, you can provide measures for a reset to a sane state, then.

This sounds even more complicated to me. In fact - I don't have any
clue, what and howto measure and reset the environment. This system
doesn't even had a reset buttom... so it is always a cold boot.

>> I don't have any connection to uboot at all, as in my final system
>> there is no serial interface to change it back.
>
> You could eventually use netconsole.

Netconsole requires (afaik) a linux kernel, that is working.

> If just the environment is hosed, it would be sufficient to provide
> some means to perform a "manufacturer reset" and restore the
> environment to a known good state. You could - for example - act on
> certain key presses / key combinations when the board is
> reset/powered on. Several boards do that.

I would do so, in fact that was my first idea. But I just have
network, nothing else.
But here I am at the beginning. How to listen on a network port ( I
know what to don in linux, but in uboot?) and howto make this change
in uboot environment to a certain state. (this can boot a system via
tftp then instead of a flash file system)

Best regards
Steffen