[U-Boot] Rescue /alternative boot

[Wolfgang Denk]

Dear Arno Steffen,

In message <AANLkTim0KjSnkOhhm9Yst8xjtNM4yINO38S35qBxdES9 at mail.gmail.com> you wrote:
> 
> The system must be ready for updates - and they might go wrong, even by a typo.

Then you must design the system to be robust and ready for such
procedures; for example, you want to have a hardware watchdog that
resets the board if something goes wrong.

> In manual I just can see how to set commandline parameters. Everything
> ( I understand until now) is controled via environment.
> I have to put some code (before the environment is read) into uboot
> source to force a tftpboot with in-compiled parameters. And I don't
> have a clue howto and where to do this.
> It is not enough to set some default environment, as this becomes
> active only if CRC is failed. This will not help against a typo in the
> setting.

The aforementioned "env default" command would alow to manually reset
the environment to default settings, for example as last resort of
recovery after a certain number of watchdog resets has been detected.

But if your environment is really hosed, including the backup copy,
then you are probably lost anyway. Foir example, how would you
communicate over Ethernet, when there is no longer a valid MAC
address in your environment?


Best regards,

Wolfgang Denk

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DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
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