Xiaomi Redmi 9

Xiaomi Redmi 9 (lancelot/galahad)

Requirements

1. PC with ADB and fastboot drivers installed.
2. Unlock bootloader with Mi Unlock or using MTK Client.
3. Flash the latest MIUI firmware: mirror 1, mirror 2, mirror 3, mirror 4, mirror 5.
4. vbmeta.img, can be obtained from the extracted MIUI firmware, it can be found in the images folder.

Download GSIs

1. Download from Generic System Image (GSI) list .
2. Extract .xz to .img

Install a GSI

1. Boot into fastboot mode.

adb reboot bootloader

Or via key combination: hold Volume Down + Power while the device is turned off.

2. Disable verified boot.

fastboot --disable-verity --disable-verification flash vbmeta vbmeta.img

3. Moving fastboot from bootloader to userspace (fastbootd)

fastboot reboot fastboot

4. Flash the GSI.

fastboot flash system system.img

Note: system.img is the extracted GSI e.g system-td-arm64-ab-vanilla.img.

5. Wipe data from MIUI recovery.

fastboot reboot recovery

Choose Wipe Data → Wipe All Data → Confirm

6. Reboot.

Return to the main menu Recovery → Reboot → Reboot to System

Update a GSI

1. Enter fastboot in userspace (fastbootd).

adb reboot fastboot

2. Flash the GSI.

fastboot flash system system.img

Note: system.img is the extracted GSI e.g system-td-arm64-ab-vanilla.img.

3. Reboot

fastboot reboot

Note: No need to wipe data as long as the image is the same e.g AOSP to AOSP or LineageOS TD-based to LineageOS TD-based NOT AOSP to LineageOS TD-based or vice versa.

Hardware support

Component	Comment
Audio	Working
Display	Working
Backlight	Working
Camera	Working but auxiliary cameras doesn't work
Bluetooth	Working
Telephony	Working
Fingerprint	Working
VoLTE	Working → Enable IMS features

General recommendations

Disable auto brightness, set brightness manually.

Reason:
Redmi 9 has scrolling (lag) issues when auto brightness is on.
I have confirmed that this also happens on MIUI.

Test:
Scrolling in a browser or other app when auto brightness is on and off.

Credits

TrebleDroid developer team for all their hard work.
All contributors for their respective contributions.