path: root/doc/uImage.FIT/source_file_format.txt
diff options
Diffstat (limited to 'doc/uImage.FIT/source_file_format.txt')
1 files changed, 19 insertions, 1 deletions
diff --git a/doc/uImage.FIT/source_file_format.txt b/doc/uImage.FIT/source_file_format.txt
index 3175c9f0b7..3db068d6c8 100644
--- a/doc/uImage.FIT/source_file_format.txt
+++ b/doc/uImage.FIT/source_file_format.txt
@@ -2,6 +2,7 @@ U-Boot new uImage source file format (bindings definition)
Author: Marian Balakowicz <>
+External data additions, 25/1/16 Simon Glass <>
1) Introduction
@@ -262,7 +263,24 @@ Older, 2.4 kernel and 2.6 non-FDT kernel do not use FDT blob, in such cases
not* be specified in a configuration node.
-8) Examples
+8) External data
+The above format shows a 'data' property which holds the data for each image.
+It is also possible for this data to reside outside the FIT itself. This
+allows the FIT to be quite small, so that it can be loaded and scanned
+without loading a large amount of data. Then when an image is needed it can
+be loaded from an external source.
+In this case the 'data' property is omitted. Instead you can use:
+ - data-offset : offset of the data in a separate image store. The image
+ store is placed immediately after the last byte of the device tree binary,
+ aligned to a 4-byte boundary.
+ - data-size : size of the data in bytes
+9) Examples
Please see doc/uImage.FIT/*.its for actual image source files.
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