[U-Boot-Users] Field upgrade

[Wolfgang Denk]

In message <3FCCA417.9020500 at 2net.co.uk> you wrote:
> 
> One of my requirements is that the firmware be field upgradeable. The 
> problem at the moment is that if something goes wrong while erasing and 
> programming a new u-boot there is no recovery without a jtag/bdm 
> debugger. Does anyone have a solution, or is it not a problem in 

There is no solution in software alone. If you have hardware  support
which for example detects a failing boot (by waiting with timeout for
a signal to be set by a successfully booting system) and then toggles
for example boot devices you can do something like that.

But there is no simple way to do this in software alone.

> practice? I was playing with the idea of having a backup u-boot and some 
> method of falling back to it if the primary copy is corrupt.

You can create a backup copy of U-Boot - but how will  you  boot  it?
U-Boot  is  linked for a fix address so you cannot easily shift it in
memory. And even if you could - your board will still  start  from  a
fix reset vector - if it does not find valifd code there you may have
a working image somewhere else but it will not help you.

Best regards,

Wolfgang Denk

-- 
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-4596-87  Fax: (+49)-8142-4596-88  Email: wd at denx.de
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