[U-Boot] Rescue /alternative boot

[Arno Steffen]

Dear Wolfgang Denk,

thanks for your mail.

2010/6/8 Wolfgang Denk <wd at denx.de>:
> Why should "flashing of uboot-environment" fail? If you configure for
> redundant environment, you should always at least have the previous
> copy of the settings).

Right, but what happens if user is doing something stupid?
I don't have any connection to uboot at all, as in my final system
there is no serial interface to change it back.
If linux is not booting anymore I am lost, as this is my only known
way to reflash uboot env, kernel, filesystem.

> updates from TFTP server etc. - Have a look at the manual for details.

I would see tftpboot as a chance - but there are a few questions to me:
- howto call this (and where?) in uboot code? It must be executed
before reading the uboot-environment, as this can misconfigured. So it
cannot be part of environment.
- howto handle boot/kernel parameters? I only know the way via
environment variables
- the timeout has to set to be very small (as this otherwise in 99%
slow down the boot process to much)

This tftpboot look smart - if I could manage this (see above).

Best regards
Arno