[U-Boot] Problem with stand-alone apps

[ANDY KENNEDY]

> From: James Chargin [mailto:jimccrown at gmail.com]
> On 08/28/2013 08:07 AM, ANDY KENNEDY wrote:
> > All,
> >
> > In an effort to play by the rules, we created a stand alone app that
> > handles breaking the boot process with bootdelay set to 0.  We require
> > a special key sequence to break into the boot process to ensure security,
> > and to ensure we do not interrupt the boot process with stray key strokes.
> > We are seeing strange behavior from our applet.  There are several API
> > calls that we make from within the app that seem to make our processor
> > go into a code violation error (even something as simple as a printf).
> 
> I'm using a much older version of U-Boot (2010.12) for the P1022. I was
> seeing some flakiness a while back. My problems were solved when I
> started using "bootm" to start my stand alone application, rather than
> "go". I don't know if this might be your problem but I thought it better
> to provide an attempt at help rather than nothing.

Jim, thanks that works.  There are some annoyances about using the bootm.
For example, we are trusting in the return code of our app.  Bootm obscures
this from us so we had to get creative on it and use env vars to pass
around return codes.  Somewhat a pain in the rear, but still, we have
something that works now.

So, another question back to the group is this:  When one builds a
stand-alone application and wraps it into a uImage, the Image has some
cool features added to it (e.g. CRC32).  What else does the mkimage header
provide?  My theory is that the code being copied out of the NOR flash
needs to be zeroed for some space AFTER the image.  Is this correct?

Andy