[U-Boot-Users] A simple howto boot sequoia (ARCH=powerpc) using flattened device tree (FDT)

[Stefan Roese]

On Friday 23 May 2008, Jerry Van Baren wrote:
> > Correct. And when the "chosen" node exists, the "bootm" doesn't override
> > the bootargs. There are three ways to change this behavior:
> >
> > a) Delete the chosen node from the dts
> > b) Run "fdt chosen" in U-Boot before booting Linux
> > c) Change U-Boot to enable overwriting the chosen node upon Linux
> >    booting without needing to call "fdt chosen"
> >
> > Currently I usually use a) if possible. So I won't add a chosen node when
> > I create a new board port. But I would like to see c) implemented too for
> > "older" arch/powerpc board ports (like Sequoia) that have a chosen node
> > in their dts. Anyone care to send a patch for this? :)
>
> Note: the difference between b) and c) is that "bootm" doesn't set the
> "force" flag but "fdt chosen" does, so "fdt chosen" overrides all
> /chosen property settings (that u-boot knows about).

Yes, I noticed this some time ago.

> It would be relatively easy to do c) by creating Yet Another Config
> Variable that bootm used for the "force" flag rather than hardcoding it.
>   I'm not wild about creating YACV.  Adding Yet Another Parameter to
> bootm is probably as bad or worse.  Hmmmm.

I'm wondering who really wants to *not* override the chosen bootargs property? 
I'm probably missing something here, but for me it just makes no sense to not 
override the bootargs property with the U-Boot bootargs env variable.

Best regards,
Stefan

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