Wolfgang, Grant, and gentle readers,
A while back I submitted a patch for a new command "oftdump". http://comments.gmane.org/gmane.comp.boot-loaders.u-boot/24664 While it was good in principle, it probably is premature and short sighted in implementation.
The command was hacked on top of ft_dump_blob() (common/ft_build.c) and required some changes to the same. Grant objected to the changes as suboptimal - I contend they are locally optimal, but that ft_build.c is suboptimal.
The linux kernel has its own library functions for handling flat device trees. In addition, David Gibson has proposed another library (advertised as easier to use): http://ozlabs.org/pipermail/linuxppc-dev/2006-November/028596.html
My RFC has two parts: 1) Peoples' opinion of the relative merits of the current u-boot support library vs. the kernel's library vs. David Gibson's library. My limited experience with ft_build.c is that it is suboptimal. I don't have any experience with the linux or David's libraries to form an opinion of them.
2) I see more commands than just dumping the tree, allowing the user to manipulate the tree as well. My current thoughts are to make a new command "fdt" (flattened device tree - the Open Firmware genesis appears to be depricated) with subcommands like the existing "mii" command.
fdt read <node> - does what my "oftdump" command does fdt write <node> <value> - allow patching the fdt * Writing could get pretty complex with creating nodes * Initial implementation would be simply to change existing values
Related to the above discussion, the current ft_build.c/"bootm" code takes the blob and augments it with board configuration and env stuff as part of the "bootm" command. The implementation is suboptimal (ft_build.c again) in that it is only done as a last thing before "bootm" transfers to linux, making it (almost) impossible to dump and definitely impossible to interactively poke around in the resulting fdt. I would like to see this integrated done better in u-boot rather than simply pasted onto the fdt at the last moment before jumping into linux.
So, in conclusion, 1) I'm not sure if this is truly a RFC or just a brain dump of my current thoughts. Either way, advice is welcome.
2) Wolfgang: Please don't apply my "oftdump" command patch yet.
gvb