[U-Boot-Users] boot control concept
wd at denx.de
Thu Feb 17 17:01:23 CET 2005
In message <4214AD81.5010007 at mc.com> you wrote:
> Our ppc440gx-based project needs to develop a "boot control" mechanism
> without any operator intervention. We have a customer PCI interface
> where "special jumper settings" will indicate if an OS should be booted
> from Flash or via TFTP.
There are several examples in the U-Boot code how to handle this; see
for example the LWMON, R360 or TRAB boards. See also
board/lwmon/README.keybd (in German).
> We also desire that once U-Boot has been installed in Flash, the user
> will ONLY be allowed to update OS and application components. This
Just tell him in the documentation. You cannot really prevent it
> I was hoping to construct a U-Boot application (similar to hello_world
> example) and do all of our "boot control" processing their. This
Should be straightforward.
> It seems there are several ways to perform this. This app could use
> native U-Boot calls to setup the environment before returning to U-Boot
> where the OS load/boot would be completed. Would this work or is their a
> better approach?
Just call you standalone application as one step in the boot
sequence. This is preferrable, as no changes to the U-Boot code are
You may have to export some additional functions - see
doc/README.standalone for instructions how to extend the jump table.
> I've looked thru the docs and email list and have not seen anything done
> like this. Any observations and suggestions about this are very welcome.
There are several examples - see above. Actually this is just another
are where U-Boot's flexibility ourperforms nearly any other boot
loader I know of.
See us @ Embedded World, Nuremberg, Feb 22 - 24, Hall 10.0 Booth 310
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
If something is different, it's either better or worse, and usually
both. - Larry Wall
More information about the U-Boot