[U-Boot] devicetree handling with chanloaded bootloader Was: [PATCH] travis: Add efi_loader grub2 test

[Stephen Warren]

On 11/18/2016 06:49 AM, Michal Suchanek wrote:
> Hello,
>
> this is like not part of this patch at all but is quite related.
>
> There is a question that bugs me for a while.
>
> I wanted to flash u-boot to an onboard memory (like a SPI NOR flash)
> alongside a devicetree for the device so I can load just bare zImage
> from anywhere the user points to and pass it the device tree from the
> flash.
>
> I could probably modify the environment to just read the devicetree
> from the flash and be done with it for bare zImage.
>
> But how do you do this when chainloading grub?

1) Ensure the previous bootloader passes the DTB pointer in a register.

2) Apply a patch to U-Boot to pick up that value, save it, and export it 
to $dtb_addr, e.g.:

http://patchwork.ozlabs.org/patch/693632/
rpi: passthrough of the firmware provided FDT blob

?