On Wed, Apr 13, 2016 at 07:42:11PM +0200, Andreas Färber wrote: [snip]
$fdtfile needs to be the Linux filename. It does not always follow the same pattern as the U-Boot variables you suggest here. CONFIG_DEFAULT_DEVICE_TREE ".dtb" might work better, and that was my question to you.
It's part of the generic mechanism, so not just select boards. Yet I was told that all boards are expected to set their cacheline size (although that is not a board but CPU property), so similarly we can (yes, newly) desire all boards to provide DT related settings as well.
If you would supply a feature-complete DT in the first place, we wouldn't need $fdtfile here, but it seemed that that was not realistic to expect for the upcoming U-Boot release.
So here's the thing. Figuring out what the device tree to load is, and where it's going to reside is a sucky problem. For most of the complex cases we do this today with "run findfdt". Why? Well, check out the implementations in "git grep -l findfdt=" right now. It sounds like we need to figure out how to get EFI in line with everything else that U-Boot does/supports rather than to re-invent the wheel here.