[U-Boot-Users] (Try 2) Please pull branch fdt-cmd from u-boot-fdt.git

Joakim Tjernlund joakim.tjernlund at transmode.se
Tue Apr 3 13:37:41 CEST 2007

On Tue, 2007-04-03 at 06:34 -0400, Jerry Van Baren wrote:
> Joakim Tjernlund wrote:
> > On Sat, 2007-03-31 at 13:43 -0400, Jerry Van Baren wrote:
> >> Dear Wolfgang,
> >>
> >> Please pull from the "fdt-cmd" branch at
> >>    git://cideas.us/pub/scm/u-boot/u-boot-fdt.git fdt-cmd
> >> currently broken, someday fixed:
> >>    git://denx.de/git/u-boot-fdt.git fdt-cmd
> >>
> >> I've resplit the patches and emailed them to the u-boot list.
> >>
> >> This change is only the starting point. :-) I've only done the
> >> mpc8360/mpc8360emds board.  Some fairly small changes need to be done
> >> to the other mpc8xxx family CPU and board subdirectories to allow them
> >> to use the libfdt/fdt command.  To see what needs adapting, see:
> >>   cpu/mpc83xx/cpu.c               |  102 +++++-
> >>   board/mpc8360emds/pci.c         |   20 +
> >>
> >> Note that I've created a new CONFIG_OF_LIBFDT that is intended to
> >> ultimately supplant CONFIG_OF_FLAT_TREE.  Use one or the other: new way
> >> CONFIG_OF_LIBFDT or old way CONFIG_OF_FLAT_TREE.  Obviously, the only 
> >> way to get the new fdt command is to use CONFIG_OF_LIBFDT.
> > 
> > This is probably a little off but I am thinking about were to
> > put my dtb on the flash and it occured to me that it could fit into the
> > environment sector as the environment doesn't use the whole sector.
> > But one can't just write it into that sector without take measures to
> > preserve the environment.
> > Is this a bad idea?
> > 
> >  Jocke
> That is an excellent idea and should be one of our goals: to better 
> coordinate the dft and env variables.  As the penultimate goal, I 
> believe we could move the env variables _into_ the dft and replace the 
> get/set env routines with dft get/set routines.  I'm still thinking 
> about this... env variables are used very early in power up (before RAM 
> is initialized), but I haven't seen any reason that it /can't/ be done.

Good, I am not totally off then :)
I think to start with one would just need an install dtb command that
places the dtb at the end of the env. sector to allow either one
to grow without trashing eachother. Also rendundant env needs to be
handled by this new command.
Secondly one needs someway of telling bootm where to find the dtb.

I have just started a board port here and there will be some time
before I get to to the dtb part.

> The downside of dfts is that the code is bigger.  My preliminary size 
> delta with the code as it stands is about +4.5K.  I don't know how much 
> we would save if we removed the env handling routines, but I'm sure 
> nowhere near that (0.5K would be my guess).  For size sensitive u-boot 
> images, we could use it read-only which would probably cut it down to 
> 1-2K, but then we would not be able to replace the env handling.
> gvb

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