How to build U-Boot with a custom out-of-tree device tree

[Johannes Krottmayer]

Hello,

This question is generic and also valid for none RISC-V boards.
I think it's maybe already asked, but didn't find any useful
information this time. My question is, is it possible to pass
a specific device tree blob to the build system from U-Boot?

Example: RISC-V board Starfive VisionFive 2 8GiB variant

The default in-source-tree device tree from the VisionFive 2 has
only 4GiB RAM. I own the 8GiB (RAM-IC BiWin BMWZCX32H2A-64G-X)
variant. So therefore can I pass the device tree blob directly
to U-Boot's build system without modifying CONFIG_DEFAULT_DEVICE_TREE
in the device configuration? Exists there an environment variable?

Want to use U-Boot's EFI subsystem as loader for bare-metal
environments. And I think when I want to get the memory map
via EFI there will with the default device tree only <4GiB free
usable memory shown, although there are 8GiB.

Thanks in advance!

Kind regards,

Johannes K.
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