[TOOL][DOCS] LG Download Mode (LAF)

Introduction
Hi folks,

While trying to get CM on a LG G3 (D855), I found people recommending Newest Root Method for LG devices (by digital-bug). Unfortunately this tool is Windows only and does not really describe what happens under the hood. For this reason I started reverse engineering the Download Mode protocol and created a Python tool that can replace the Send_Command.exe binary.

This project is aimed at users who would like to dump or restore partitions and developers who need some power in download mode.

Source code: https://github.com/Lekensteyn/lglaf
(Protocol documentation: https://github.com/Lekensteyn/lglaf/...er/protocol.md)

Features

• Should work on any LG device.
• Dump and restore partitions.
• Dump individual files.
• Run any shell command as root in Download Mode.
• Works on Linux.
• Works on Windows.
• Opensource code and protocol documentation.

Installation instructions
See the README for details. Basically:

1. Install Python (www.python.org)
2. Install PyUSB (Linux) or LG drivers (Windows)
3. Ensure phone is connected and started in Download Mode (poweroff, hold Volume Up and insert USB cable in a PC).
4. Run the tool of your choice (lglaf.py, partitions.py, etc.)

Examples
Some examples are listed in the README, here are additional ones:

List partitions, dump the userdata partition (/data) to a local "data.bin" file (may take a while):
Dump all partitions (except ones larger than 64 MiB: cache, userdata, system, cust):
Backup the contents of the data partition (assuming it to be small enough to fit in /) and retrieve it:
Get more usage information on these tools:
Q&A
Q: What devices are supported?
A: In principle all LG devices as they all use the same download mode. Tested with G2, G3, G4 (see README).

Q: How can I root a device with this?
A: This depends on your currently installed ROM. Feel free to post a guide.

Q: How can I install a custom ROM using this?
A: With older bootloader versions, you should be able to write a "bumped" recovery image:
Newer versions (such as my G3 (D855 with 20T)) do not support the "bump" method and will refuse to boot ("ERROR: Boot certification verify").
In that case, wipe the recovery partition and you will end up in the fastboot mode where you can boot your custom images:
XDA:DevDB Information
LG Download Mode utility (LGLAF.py), Tool/Utility for all devices (see above for details)

Contributors
Lekensteyn
Source Code: https://github.com/Lekensteyn/lglaf


Version Information
Status: Beta

Created 2016-01-04
Last Updated 2016-01-04