[U-Boot-Users] Warning for mpc8360emds users: fdt-cmd from u-boot-fdt.git

[Jerry Van Baren]

Timur Tabi wrote:
> Jerry Van Baren wrote:
> 
>> As a result, if you pull an update from the master u-boot repository, 
>> you will get the new fdt command, libfdt support, *and modified bootm* 
>> command.  While this shouldn't be a bad thing, it *is not* backward 
>> compatible with CONFIG_OF_FLAT_TREE.
> 
> I'm a little confused.  CONFIG_OF_FLAT_TREE is needed to boot any 
> powerpc kernel.  Are you saying that the two options are mutually 
> exclusive?  Shouldn't CONFIG_OF_LIBFDT be a subset (instead of an 
> alternative) to CONFIG_OF_FLAT_TREE?  That is, you need to define 
> CONFIG_OF_FLAT_TREE in order for CONFIG_OF_LIBFDT to be recognized?
> 
> Maybe I should have been paying more attention to your libfdt work, but 
> I was assuming you were just going to alter the back-end handling of OF 
> trees, not break existing code.

Hi Timur,

Using CONFIG_OF_FLAT_TREE results in an unchanged u-boot image, no 
libfdt, no "fdt" command, backwards compatibility.

The incompatibility with CONFIG_OF_LIBFDT is that "bootm" does *not* 
auto-generate nodes ("chosen", "u-boot-env", and "bd_t") when it runs. 
With CONFIG_OF_LIBFDT, I expect the boot script or the user to use the 
sequence:
* "fdt addr" command to set the blob address
* "fdt chosen" to generate/augment the chosen node
* "fdt env" to generate the u-boot-env node (optional)
* "fdt bd_t" to generate the bd_t node (optional)

I view autogenerating fdt entries inside "bootm" as being evil. 
Obviously, if there are enough people on the Dark Side to overwhelm me, 
that can be changed.

NOTE: I've probably screwed up the multi-image.  Note to self, fix it - 
need to find the fdt blob in a multi-image and implicitly set the "fdt 
addr" to it.

Best regards,
gvb