[U-Boot] NAND bad environment block handling

[Schlaegl Manfred jun.]

Hi!
Am Sonntag, den 11.01.2009, 05:26 -0800 schrieb Frans Meulenbroeks:
> Manfred,
> 
> Thanks for your suggestions.
> Did you modify u-boot to search from the last block of the device backwards?
> I feel putting the env at the end is quite a good idea.
> 
Yes. First I wanted to implement the openmoku-solution: putting the
address of env-block in first block oob.
But then I thought it would be much simpler to put the env at the second
distinctive position on a nand device - the end.

Yes, I had to do some modification on uboot. But I had to do this on
uboot-1.1.3(delivered by our hardware-supplier) which is quite old. I'm
currenty on work to port our architecture to 2009q1.

> 
> Unfortunately in our system we need to modify the env at runtime.
The solution to put the environment at end of device may also be
combined with redundant environment.

> For software upgrade we aim to go for a ping pong strategy (so having two kernels and two rfs-es in flash, and upgrade the non active kernel, then modify u-boot env so the next time we boot from the upgraded kernel).
> Unless of course there is a better strategy for this.
Yes. Its a very common strategie. We also use two kernel-partitions.

- Manfred