[U-Boot-Users] My first embedded project

Roger Larsson roger.larsson at norran.net
Fri Feb 11 14:57:39 CET 2005

On Friday 11 February 2005 00.11, Wolfgang Denk wrote:
> In message <OF148F35BA.97D68C7A-ON07256FA4.007D54A4 at mck.us.ray.com> you 
> > 1. Is there a way to use U-boot without an EEPROM. Can we use U-b oot
> > with
> U-Boot does not need any EEPROM at all.
> Ummm... maybe you meant flash memory when you wrote EEPROM?
> Even then, U-Boot does not need any flash at all,  either.  [Although
> it makes some things much easier.]
> > its environmental variables on the Compactflash card?
> Short answer: no, this is not possible.
> In the current code there is no support for storing  the  environment
> in  CF;  adding this feature is non trivial and not possible withouit
> major reorganization of the U-Boot code.
> Remember that the environment must be  accessable  very  early,  even
> before  the  system  RAM  has  been  initialized,  i.  e.  in  a very
> restricted environment with just a minimal stack,  no  writable  data
> segment,  etc.  Compact  Flash  (or  more  generally: IDE) support is
> enabled much, much later in the boot sequence.

Shouldn't it be possible to do this in two stages.
1) Have environment variables in flash/EEPROM so you can mount the CF disk
2) Run an autoscript(?) from that disk to change the variables (do not save)
3) Boot


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