How to make an Android firmware dump with your own hands

Creating a full backup of the system partitions of the device, or the so-called firmware dump, is a critical step before carrying out complex modifications to the smartphone. Unlike a regular backup of contacts or photos, a dump is a bit-by-bit copy of the contents of flash memory, including hidden sections of the bootloader and kernel. This allows you not only to save data, but also to completely restore the functionality of the Androiddevice in case of unsuccessful flashing or damage to system files.

The procedure for creating a dump may be required by developers to analyze the operation of a specific model, by enthusiasts to port firmware, or by ordinary users who want to protect yourself from “scrapping” your gadget. It is important to understand that the methods for obtaining a copy vary depending on the presence root access, unlocked bootloader and installed custom recovery. Without proper preparation, attempting to access system partitions may result in loss of warranty or unstable operation of the device.

In this guide, we will look at the most reliable and proven methods for creating backup copies of partitions boot, recovery, system and other critical memory areas. We will look in detail at working with console utilities via a computer and methods available directly on the device. Remember that any manipulations with low-level access to the file system require extreme care and understanding of the data storage structure in Android.

⚠️ Attention: You perform all actions described in the article at your own peril and risk. The author is not responsible for possible data loss or device failure. Before starting work, make sure that the battery is charged at least 70%.

Preparing the working environment and drivers

The first step towards creating a high-quality dump is the correct organization of the workplace. You will need a computer running Windows, Linux or macOS, a working USB cable (preferably an original one that supports data transfer, not just charging) and the smartphone itself. The key element of success here is the installation of the correct ADB drivers, without which the computer will not be able to correctly interact with the device in debugging mode.

You must activate developer mode on the phone itself. To do this, go to the menu Settings → About phone and quickly click seven times on the item Build number. After a notification appears that you have become a developer, go to the new menu section For developers and activate the switch USB debugging. When you connect the cable to the PC, a request to confirm debugging will appear on the smartphone screen - be sure to click “Allow” and check the box “Always allow from this computer.”

To work, we need a package of platform tools Android SDK Platform-Tools. Download it from the official website of the developers and unpack it into a convenient directory, for example C:\platform-tools. Opening a command line or terminal in this folder will allow you to run commands without having to enter the full paths to the executable files. Check the connection by entering the command adb And fastboot without the need to specify full paths to executable files. Check the connection by entering the command adb devices: the list should display your device with serial number and status device.

Method of creating a dump via ADB without root access

If your smartphone has a locked bootloader and does not have superuser rights, the possibility of creating full system image are limited. The standard protocol ADB does not allow raw data to be read directly from memory sections for security reasons. However, you can back up user data and some settings using the built-in backup utility.

Run the command in the terminal, connecting the device in normal mode:

adb backup -apk -shared -all -system -f backup.ab

The backup confirmation interface will appear on the phone screen. Here you can set a file encryption password backup.abwhich will add a layer of protection to your data. Please note that this method does not create a sector-by-sector copy of the partition boot or recovery, but only archives applications and their data in a special format, which will later need to be converted to tar to extract files.

To obtain deeper access without root access, it is sometimes used mode fastboot, but it is intended primarily for writing, not reading. Attempts to read partitions through fastboot flash are impossible. The only exception may be some manufacturer-specific engineering modes, such as Xiaomi or Motorola, where there are specific commands for dumping, but they are unique to each model and often require signed bootloaders.

Limitations of the ADB backup method

The adb backup command does not save data from protected memory areas, such as DRM encryption keys or modem settings. This method is not suitable for completely cloning a device; it only serves to migrate user data.

Receiving a dump of partitions with Root access

Having superuser rights (root) radically changes the situation, opening direct access to block devices in the directory /dev/block/. This folder contains symbolic links to the physical sections of your smartphone's memory. To create a dump, you must first determine what name in the system the desired partition is designated, for example, boot or recovery.

Connect the phone with debugging enabled and root access to the computer. Enter the command to enter the device shell:

adb shell

Then request superuser rights with the command su and confirm the request on the smartphone screen. To find the desired section, you can use the utility ls -l /dev/block/by-name/, which will display a list of all sections with their real names. Once you find the name you need (for example, boot), find out its real block device, which usually looks like /dev/block/mmcblk0pX or /dev/block/sdaX.

The copying process itself is performed by a command ddthat reads the data bit by bit. The command syntax is as follows:

dd if=/dev/block/mmcblk0p12 of=/sdcard/boot.img

Here the parameter if indicates the source (input file), and of indicates the destination (output file). After executing the command, the file boot.img will appear in the internal memory of the phone. You can download it to your computer using the command adb pull /sdcard/boot.img. This method allows you to save an exact copy of any partition to which the kernel has read access.

Creating a system image via TWRP Recovery

The most convenient and safe way to create a full firmware dump is to use a custom recovery, such as TWRP (Team Win Recovery Project). This tool has a graphical interface and a built-in backup feature that automatically detects all the necessary partitions to keep the system running. To use this method, the bootloader must be unlocked on the device and the recovery itself must be installed.

Boot into recovery mode, usually this is done by pressing the volume and power keys when turning on the device. In the TWRP main menu, select Backup. Before starting the process, you will see a list of available sections for selection: Boot, System, Data, Vendor, EFS and others. It is critical to check the sections EFS or Persist, as they contain unique hardware identifiers (IMEI, MAC addresses), the loss of which can make the phone unusable for communication.

After selecting the sections, swipe the slider to begin the process. TWRP will create archives of images in the format .win or raw images .img in a folder /TWRP/BACKUPS/ on the internal drive or SD card. The advantage of this method is the integrity of the data: the recovery works outside the main operating system, which guarantees that there are no errors in reading files that may be blocked by the working one. The finished files can be copied to a PC via an MTP connection or ADB. Android. Finished files can be copied to a PC via an MTP connection or ADB.

⚠️ Attention: The EFS/Persist section contains unique calibration data for your device. Never flash an EFS dump from another phone, even the same model - this will lead to loss of network and unique identifiers.

Analysis of partition structure and partition tables

Understanding how data storage is organized helps to avoid fatal errors when working with dumps. Modern devices use a partition table that describes the beginning and end of each logical volume on the physical memory chip. The command cat /proc/partitions or fdisk -l (in a Linux environment on a PC for a connected block device) allows you to see this structure.

Below is an example table of the correspondence of partition names and their purpose in a typical architecture Android:

Partition name	Description of contents	Criticality
boot	Linux kernel and ramdisk (initial file system)	High (the phone will not boot without it)
recovery	Recovery and update environment	Medium (needed for resetting and flashing)
system	Main operating system and pre-installed applications	High (contains OS)
userdata	User data, applications, photos, settings	Critical (loss of personal data)
misc	Different switch settings and update flags	High (errors can cause a cyclic reboot)

It is important to note that in devices with support Project Treble and implementation dynamic partitions structure may differ. Here, system images can be stored in logical volumes on top of a physical partition super. In such cases, creating a dump through a simple command dd requires knowledge of the exact offsets or the use of utilities like lpdump to correctly extract data from the container super.

Restoring a device from a created dump

Having a dump is useless without the ability to restore it correctly. The return process depends on the file format you received and the method you used. If you have a raw image .imgobtained via dd or TWRP, you can write it back to the partition via mode fastboot or a terminal with root access.

To restore via fastboot switch the device to the appropriate mode and run the command:

fastboot flash boot boot.img

Replace boot with the name of the target partition, and boot.img with the name of your dump file. If the recovery is performed from the TWRP environment, use the function Restore, selecting the previously created backup folder. The system will automatically offer to restore the selected partitions. After completing the procedure, be sure to clear the cache (Wipe Cache/Dalvik) to avoid conflicts between the restored system files and temporary data.

In cases where the device does not turn on at all (“bricked”), you may need to use specialized software from the manufacturer, such as Odin for Samsung, SP Flash Tool for processors MediaTek or QFIL for Qualcomm. These tools work at a lower level than fastboot and allow you to write dumps directly to memory, bypassing the bootloader, but require Scatter files or specific configurations.

⚠️ Attention: The interfaces of the firmware apps (SP Flash Tool, Odin) and drivers are updated frequently. The functionality of the buttons and the location of options may differ in new versions. Always check the official documentation for the specific version of the utility before starting recording.

Frequently asked questions (FAQ)

Is it possible to make a firmware dump without unlocking the bootloader?

Full sector-by-sector dump of system partitions (boot, recovery) without Unlocking the bootloader and rooting is almost impossible to do due to Android security limitations. Only backup of user data is available via adb backup, which is not a full system image.

Where are the dump files stored after creation via TWRP?

By default, TWRP saves backups in the internal memory of the device along the path /TWRP/BACKUPS/[device_serial_number]/[date_time]. If an SD card is selected in the recovery settings, then the files will be located on it in a similar folder structure.

What to do if, after restoring a dump, the phone goes into a cyclic reboot?

This often occurs due to incompatibility of the recovered data with the current kernel or damaged cache files. Try going into recovery and cleaning partitions Cache and Dalvik / ART Cache. If the problem persists, the dump may have been made from a different firmware version, and a complete flashing of the stock image will be required.

What is the difference between a system partition dump and a full firmware?

A partition dump system contains only operating system and application files. Full firmware (ROM) usually includes images of all partitions: boot, recovery, system, vendor, modem and others, necessary for the full operation of the hardware and communications.