Failsafe bootloader

Wolfgang Denk wd at
Wed Jun 4 07:51:15 EST 2003

In message < at> you wrote:
> Check out U-Boot
> The project page on sourceforge is pretty much non-existant other than the
> CVS link.  Pull down the source -- there _is_ a good README file in it that
> explains a lot about u-boot.
> Wolfgang Denk of Denx Computer Systems runs the project.  He doesn't appear

Actually this is Wolfgang Denk of DENX Software Engineering :-)

> to have anything on U-Boot on his web site either.

Well, we do have some documentation about PPCBoot at

which can be used directly for U-Boot, too.

> The predecessor was ppcboot, which at least has a home page on sourceforge
> Pretty much everything said for ppcboot goes for u-boot as well, only
> better :-).

Right :-)

> U-boot has some scripting capabilities as well as variables that can be
> used for rudimentary decision making.  I'm sure Wolfgang will welcome
> improvements to the scripting :-).

The "some scripting capabilities" includes a more  or  less  complete
bourne   shell   (the   "hush"   shell  from  busybox).  Things  like
if/then/else/fi,   for/do/done,   while/do/done,   until/do/done   or
operators like && and || are available.

For a trivial example: to recover from corrupted images (bad checksum
etc.) you could use

	setenv bootcmd 'bootm $addr_primary || bootm $addr_secondary'


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
"A fractal is by definition a set for which the Hausdorff Besicovitch
dimension strictly exceeds the topological dimension."
- Mandelbrot, _The Fractal Geometry of Nature_

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