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

Jerry Van Baren gvb.uboot at gmail.com
Tue Apr 3 12:34:01 CEST 2007

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.

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.


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