Be aware that this environment variable is checked prior to relocation,
when only the compiled-in environment is available. Therefore it is not
possible to define this variable in the saved SPI/NAND flash
-environment, for example (it will be ignored).
+environment, for example (it will be ignored). After relocation, this
+variable will be set to the address of the newly relocated fdt blob.
+It is read-only and cannot be changed. It can optionally be used to
+control the boot process of Linux with bootm/bootz commands.
To use this, put something like this in your board header file: