In message D61182AC8012EA4EBC531B3AF23BE109480232@tranzeo-mail2.12stewart.tranzeo.com you wrote:
I have looked at some of the u-boot code for booting up a linux kernel. It appears that the determination of whether or not to make use of flattened device tree (fdt) in the boot is a compile time selection.
No, this is not the case. You can use a FDT-enabled U-Boot to boot kernel images which use a FDT, and of course such that don't, too.
Can we determine during runtime from info in the uImage whether the linux kernel was built as arch/ppc or as arch/powerpc and then select the fdt support accordingly?
No. There is no such information available in the current image format.
It will soon be possible to build a U-Boot for one or the other (for ppc4xx family). I think I will need to implement a U-Boot that will
This is not correct. You can build U-Boot without FDT-support, and this will only work with old (arch/ppc) kernels, or with arch/powerpc kernels using the bootwrapper (cuImage). Or you can build U-Boot *with* FDT-support, which can do exactly the same, *plus* directly boot FDT enabled Linux kernels.
I think we need the U-Boot to be able to support both but detect which one the uImage was built under.
The first part of the sentence is true, and describes the current state of things, and the second part is IMO not needed.
In the image.h file, there appears to only be one selection for powerpc so there will likely be need for some other "magic" to make this work. Has anyone checked into this before, or come up with a workable solution?
I see no need for any such changes.
Best regards,
Wolfgang Denk