path: root/doc
diff options
Diffstat (limited to 'doc')
2 files changed, 28 insertions, 1 deletions
diff --git a/doc/mkimage.1 b/doc/mkimage.1
index 036b095c1b..e0f210ab52 100644
--- a/doc/mkimage.1
+++ b/doc/mkimage.1
@@ -112,6 +112,15 @@ Provide special options to the device tree compiler that is used to
create the image.
+.BI "\-E
+After processing, move the image data outside the FIT and store a data offset
+in the FIT. Images will be placed one after the other immediately after the
+FIT, with each one aligned to a 4-byte boundary. The existing 'data' property
+in each image will be replaced with 'data-offset' and 'data-size' properties.
+A 'data-offset' of 0 indicates that it starts in the first (4-byte aligned)
+byte after the FIT.
.BI "\-f [" "image tree source file" " | " "auto" "]"
Image tree source file that describes the structure and contents of the
FIT image.
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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