Add dumpimage, a tool to extract data from U-Boot images

Given a multi-file image created through the mkimage's -d option:

  $ mkimage -A x86 -O linux -T multi -n x86 -d vmlinuz:initrd.img:System.map \
  multi.img

  Image Name:   x86
  Created:      Thu Jul 25 10:29:13 2013
  Image Type:   Intel x86 Linux Multi-File Image (gzip compressed)
  Data Size:    13722956 Bytes = 13401.32 kB = 13.09 MB
  Load Address: 00000000
  Entry Point:  00000000
  Contents:
     Image 0: 4040128 Bytes = 3945.44 kB = 3.85 MB
     Image 1: 7991719 Bytes = 7804.41 kB = 7.62 MB
     Image 2: 1691092 Bytes = 1651.46 kB = 1.61 MB

It is possible to perform the innverse operation -- extracting any file from
the image -- by using the dumpimage's -i option:

  $ dumpimage -i multi.img -p 2 System.map

Although it's feasible to retrieve "data files" from image through scripting,
the requirement to embed tools such 'dd', 'awk' and 'sed' for this sole purpose
is cumbersome and unreliable -- once you must keep track of file sizes inside
the image. Furthermore, extracting data files using "dumpimage" tool is faster
than through scripting.

Signed-off-by: Guilherme Maciel Ferreira <guilherme.maciel.ferreira@gmail.com>
Signed-off-by: Simon Glass <sjg@chromium.org>

1 files changed, 9 insertions, 0 deletions

diff --git a/README b/README
index 8f0b38c..895fef3 100644
--- a/README
+++ b/README
@@ -5252,6 +5252,15 @@ when your kernel is intended to use an initial ramdisk:
 	Load Address: 0x00000000
 	Entry Point:  0x00000000
 
+The "dumpimage" is a tool to disassemble images built by mkimage. Its "-i"
+option performs the converse operation of the mkimage's second form (the "-d"
+option). Given an image built by mkimage, the dumpimage extracts a "data file"
+from the image:
+
+	tools/dumpimage -i image -p position data_file
+	  -i ==> extract from the 'image' a specific 'data_file', \
+	   indexed by 'position'
+
 
 Installing a Linux Image:
 -------------------------