extract-dtb

Tool to split a kernel image with appended dtbs into separated kernel and dtb files.

A Device Tree is a data structure for describing hardware. They are used in a lot of ARM devices (e.g. Android), otherwise these would not be able to boot.

This tool is similar to split-appended-dtb but it is written in Python and its code is simpler and almost 3x shorter.

If you want to learn more about DTB you can have a look at the Device Tree Reference.

Usage

$ ./extract-dtb.py --help
usage: extract-dtb.py [-h] [-o OUTPUT_DIR] [-n] [-V] filename

Extract dtbs from kernel images.

positional arguments:
  filename       Android kernel image

optional arguments:
  -h, --help     show this help message and exit
  -o OUTPUT_DIR  Output directory
  -n             Do not extract, just output information
  -V, --version  show program's version number and exit

Example:

$ ./extract-dtb.py -n /tmp/postmarketOS-export/vmlinuz-motorola-titan
Found 9 appended dtbs

$ ./extract-dtb.py /tmp/postmarketOS-export/vmlinuz-motorola-titan -o /tmp/dtb
Dumped kernel, start=0 end=7534024
Dumped dtbdump_01_Motorola_QC-MSM8226_Titan.dtb, start=7534024 end=7728853
Dumped dtbdump_02_Motorola_QC-MSM8226_Titan.dtb, start=7728853 end=7923682
Dumped dtbdump_03_Motorola_QC-MSM8226_Titan.dtb, start=7923682 end=8118511
Dumped dtbdump_04_Motorola_QC-MSM8226_Titan.dtb, start=8118511 end=8313340
Dumped dtbdump_05_Motorola_QC-MSM8226_Titan.dtb, start=8313340 end=8508169
Dumped dtbdump_06_Motorola_QC-MSM8226_Thea.dtb, start=8508169 end=8700762
Dumped dtbdump_07_Motorola_QC-MSM8226_Thea.dtb, start=8700762 end=8894086
Dumped dtbdump_08_Motorola_QC-MSM8226_Thea.dtb, start=8894086 end=9087470
Dumped dtbdump_09_Motorola_QC-MSM8226_Thea.dtb, start=9087470 end=9280854
Extracted 9 appended dtbs + kernel to /tmp/dtb

$ ls -l /tmp/dtb/
total 9088
-rw-rw-r-- 1 pablo pablo  194829 Aug 21 01:48 dtbdump_01_Motorola_QC-MSM8226_Titan.dtb
-rw-rw-r-- 1 pablo pablo  194829 Aug 21 01:48 dtbdump_02_Motorola_QC-MSM8226_Titan.dtb
-rw-rw-r-- 1 pablo pablo  194829 Aug 21 01:48 dtbdump_03_Motorola_QC-MSM8226_Titan.dtb
-rw-rw-r-- 1 pablo pablo  194829 Aug 21 01:48 dtbdump_04_Motorola_QC-MSM8226_Titan.dtb
-rw-rw-r-- 1 pablo pablo  194829 Aug 21 01:48 dtbdump_05_Motorola_QC-MSM8226_Titan.dtb
-rw-rw-r-- 1 pablo pablo  192593 Aug 21 01:48 dtbdump_06_Motorola_QC-MSM8226_Thea.dtb
-rw-rw-r-- 1 pablo pablo  193324 Aug 21 01:48 dtbdump_07_Motorola_QC-MSM8226_Thea.dtb
-rw-rw-r-- 1 pablo pablo  193384 Aug 21 01:48 dtbdump_08_Motorola_QC-MSM8226_Thea.dtb
-rw-rw-r-- 1 pablo pablo  193384 Aug 21 01:48 dtbdump_09_Motorola_QC-MSM8226_Thea.dtb
-rw-rw-r-- 1 pablo pablo 7534024 Aug 21 01:48 kernel

This tool can also be run directly on boot.img images.