powerpc/p1010rdb: add readme document for p1010rdb

[karo-tx-uboot.git] / doc / README.fdt-control

diff --git a/doc/README.fdt-control b/doc/README.fdt-control
index 3f8bb5a670175088c0147e7d6d57cefc36c1a32d..5963f78e96117113f03ea86acb8911b987d078a1 100644 (file)
--- a/doc/README.fdt-control
+++ b/doc/README.fdt-control
@@ -142,7 +142,31 @@ join the two:
 
 and then flash image.bin onto your board.
 
-You cannot use both of these options at the same time.
+If CONFIG_OF_HOSTFILE is defined, then it will be read from a file on
+startup. This is only useful for sandbox. Use the -d flag to U-Boot to
+specify the file to read.
+
+You cannot use more than one of these options at the same time.
+
+If you wish to put the fdt at a different address in memory, you can
+define the "fdtcontroladdr" environment variable. This is the hex
+address of the fdt binary blob, and will override either of the options.
+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).
+
+To use this, put something like this in your board header file:
+
+#define CONFIG_EXTRA_ENV_SETTINGS      "fdtcontroladdr=10000\0"
+
+Build:
+
+After board configuration is done, fdt supported u-boot can be build in two ways:
+1)  build the default dts which is defined from CONFIG_DEFAULT_DEVICE_TREE
+    $ make
+2)  build the user specified dts file
+    $ make DEVICE_TREE=<dts-file-name>
 
 
 Limitations