[U-Boot-Users] builtin OF tree dtb gone

Joakim Tjernlund joakim.tjernlund at transmode.se
Sun Dec 17 15:23:30 CET 2006

> -----Original Message-----
> From: wd at denx.de [mailto:wd at denx.de] 
> Sent: den 17 december 2006 01:38
> To: Joakim Tjernlund
> Cc: u-boot-users at lists.sourceforge.net
> Subject: Re: [U-Boot-Users] builtin OF tree dtb gone 
> In message <007701c7214c$a1c6f430$1e67a8c0 at Jocke> you wrote:
> >
> > Don't like this idea, its not a runtime/kernel load feature, IMHO.
> > What devices that is supported should be provided by firmware.
> Then store the DTB in flash, probably as part of  your  production  /
> update mechanism. Nobody prevents you from doing this.

Well, newer versions of U-boot prevents me from embedding the OF tree
inside the u-boot image.

> > > I disagree here.
> > 
> > Clearly, but you don't say why. You are saying that a 
> multi-file image
> > might work but that won't work in a system where you need 
> different OF trees.
> Of course not.
> > I am supposed to supply X multi-file images, one for each 
> board where only the
> > DTB differ?
> No.
> For a complete system you need U-Boot  plus  DTB  plus  Linux  kernel
> [plus  root file system ...]. You may find, that for different boards
> any of these components may be different or the same,  so  no  matter
> which  you  bundle  together it will work fine in some setups, and be
> unconvenient in others. The best flexibility is when  all  three  are
> separate,  so  that's  the  default option we provide. If you want to
> combine U-Boot plus DTB, fine, you define your [flash] memory map. If
> you want to combine Linux and DTB, ok, use a multifile image.

"in some setups", that's the point. Our setup works fine with
an embedded OF tree in u-boot. If I am to adapt to this new
method of supplying the OF tree, not only will I have to repartion
the flash to fit the tree in there, I also need to make sure
that some 15-20 people learns this new concept for no real gain.

It is nothing wrong with having the ability provide a OF tree
at boot time, but forcing everyone to do so is. The
most flexible way is to have both.

> Best regards,
> Wolfgang Denk

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