dtboverlay to U-Boot runtime dtb

[Peter Robinson]

Hi Peng,

> I did a test to do overlay for U-Boot runtime dtb, but after overlay
> finish, U-Boot DM driver not work properly because the of_node
> pointer is changed in a device.
>
> So I am thinking whether this is valid to overlay to runtime U-Boot
> dtb or not. The reason I try this is that I wanna overlay the EFI capsule
> signature to U-Boot dtb, then capsule update with authentication
> could work, otherwise I need integrate the signature in dts and
> rebuild the image. I understand current U-Boot not support
> overlay U-Boot runtime dtb, just thinking whether this is valid or
> should we support it.

Bootin did a pretty good blog post for DT overlays in U-Boot, not sure
if that's useful for this usecase but for reference:
https://bootlin.com/blog/using-the-u-boot-extension-board-manager-beaglebone-boards-example/