Install / Pixel 4a

Terminology

• Factory Image: This is a zip file that contains the entire CalyxOS operating system to be installed on your device.
• Flashing: On Android devices, installing a new operating system is called “flashing,” because it writes a new factory image to the device’s flash memory.
• Android Device: The device that you are installing CalyxOS on to.
• Host Computer: The Linux computer used to send commands to the Android Device. You will connect this computer to the Android device and run device-flasher to install CalyxOS.
• Fastboot: A mode of the Android device needed to install a custom Operating System. At various stages, you will be asked to put your Android device in Fastboot mode.

Prepare your Android device

There are a few things you must do to prepare your device to accept a new operating system:

Remove SIM card

On brand new devices, especially those obtained from a carrier, it’s better to remove the SIM card from the device before starting it for the first time, to help with the “OEM Unlocking” step below.

Enable Developer Options

Settings → About Phone → tap Build number 7 times

Enable USB debugging

Settings → System → Advanced → Developer Options → USB Debugging

Enable OEM Unlocking

Settings → System → Advanced → Developer Options → OEM unlocking

This step might fail if there is no internet connection. In that case, connect to a WiFi network and then try again.

Prepare your host computer

Linux packages

The device-flasher program needs certain udev rules installed. You should install one of the following packages to correctly set the udev rules.

Debian, Ubuntu, & derivatives:

sudo apt update
sudo apt install android-sdk-platform-tools-common

Fedora & derivatives:

sudo dnf install android-tools

Currently, there are issues with udev rules on Fedora, you may need to run device-flasher.linux using sudo later on the install process.

Arch Linux:

sudo pacman -S android-udev

openSUSE:

sudo zypper install android-udev-rules

NixOS:

Add the following to /etc/nixos/configuration.nix and sudo nixos-rebuild switch:

services.udev.packages = [
  pkgs.android-udev-rules
];

Create a shell.nix for temporary FHS-compatible shell:

{ pkgs ? import <nixpkgs> {} }:

(pkgs.buildFHSUserEnv {
      name = "calyxos-device-flashing";
}).env

Enter it with nix-shell.

Download device-flasher

Download device-flasher.linux

Save this executable to a new directory, where you will also later save the CalyxOS image.

Verify Digest

This is an optional step, useful for ensuring you have the correct device-flasher executable. Open a terminal on your host computer, change to the directory where you saved device-flasher, and then run:

sha256sum device-flasher.linux

And ensure the result says 90c306006c8f6ff74a6fc264b85349f9dce4f0e790f673d7c3c8b8a9e083284b. This is the unique digest of the device-flasher. If it doesn’t match, then you have a corrupted or incorrect file.

Download factory image

Download CalyxOS Image

Save this image in the same directory as device-flasher. This image will only work for Pixel 4a (sunfish). Any attempt to install this image on a different device model may brick (destroy) the Android device.

Do not extract or rename the zip, simply copy it as-is.

Once downloaded, the next step is to verify the image. This step is optional, but verification helps ensure that you downloaded the image correctly, and that you got the correct image.

Verify Digest

To verify the image, open a terminal window on the host computer where you saved the image and run the command:

sha256sum sunfish-factory-24512012.zip

And ensure the result says 1827e9b4f75b145e22fe3cc5f065ba3460dba43f697f7b5697e14bdb4f574f6b. This is the unique digest of the image file. If it doesn’t match, then you have a corrupted or incorrect file.

Verify Signature

For the highest level of confidence, you can optionally download the signature file and then verify image signature.

Install CalyxOS

Run device-flasher

Now you are ready to install. Ensure that both the CalyxOS image and device-flasher are in the same directory.

Step 1. Connect the USB cable between the computer and the Android device.

Step 2. Run device-flasher

Open a terminal, change to the directory with the firmware image, and run:

chmod +x device-flasher.linux
./device-flasher.linux

Unlock the bootloader

At some point in the installation process, it will ask you to unlock the bootloader.

NOTE: if the bootloader is already unlocked, you will not see the unlock bootloader menu and installation will proceed automatically without you needing to touch anything.

The bootloader unlock menu looks like this:

Press a volume key to select UNLOCK THE BOOTLOADER option. Then press the power key to activate that option.

Success?

Once device-flasher is finished, you should now have a fully functional CalyxOS device. If not, please see our Community page for where you can post your questions.

Troubleshooting

Error running device-flasher

If you get a mysterious error when running device-flasher, or if device-flasher hangs, it may be a USB problem. Try connecting to a different USB port on your computer (yes, not all USB ports are created equal) or a different USB cable.

How do I tell if the bootloader is locked?

In Fastboot “Device State: locked” means the bootloader is locked.

On the initial boot screen, you may also see this if the bootloader is unlocked:

The bootloader is unlocked and software integrity cannot be guaranteed. Any data stored on the device may be available to attackers. Do not store sensitive data on the device.

Back to Stock

If you would like to return to the default operating system, please see Back to Stock Android.

Security Notes