fit: fdt overlays doc

[oweals/u-boot.git] / doc / uImage.FIT / source_file_format.txt

diff --git a/doc/uImage.FIT/source_file_format.txt b/doc/uImage.FIT/source_file_format.txt
index 32825eda8d571b1d3eca1e100aec394ed0a3ec63..6f727a1e8a2fe7d91f4af7d7ed4a9170a9369e01 100644 (file)
--- a/doc/uImage.FIT/source_file_format.txt
+++ b/doc/uImage.FIT/source_file_format.txt
@@ -235,7 +235,7 @@ o config@1
   |- description = "configuration description"
   |- kernel = "kernel sub-node unit name"
   |- ramdisk = "ramdisk sub-node unit name"
-  |- fdt = "fdt sub-node unit-name"
+  |- fdt = "fdt sub-node unit-name" [, "fdt overlay sub-node unit-name", ...]
   |- fpga = "fpga sub-node unit-name"
   |- loadables = "loadables sub-node unit-name"
 
@@ -249,7 +249,9 @@ o config@1
   - ramdisk : Unit name of the corresponding ramdisk image (component image
     node of a "ramdisk" type).
   - fdt : Unit name of the corresponding fdt blob (component image node of a
-    "fdt type").
+    "fdt type"). Additional fdt overlay nodes can be supplied which signify
+    that the resulting device tree blob is generated by the first base fdt
+    blob with all subsequent overlays applied.
   - setup : Unit name of the corresponding setup binary (used for booting
     an x86 kernel). This contains the setup.bin file built by the kernel.
   - fpga : Unit name of the corresponding fpga bitstream blob