Install GSI (Generic System Image) on Android
Can't find a custom ROM for your device? Thanks to Project Treble, you might not need one. GSIs let you run generic Android ROMs on almost any modern device.
What is a GSI?
GSI (Generic System Image) is a pure Android implementation that works on any Treble-compatible device.
How It Works
Traditional custom ROMs:
ROM built specifically for your device
includes: system + device-specific code
GSI approach:
Generic ROM → Your device's vendor/HAL
Works on any Treble device
Project Treble
Google's Project Treble (Android 8.0+) separated:
- System: Android OS (can be replaced with GSI)
- Vendor: Hardware-specific code (stays on device)
This means one GSI works on thousands of devices!
Is Your Device Compatible?
Check Treble Support
Method 1: Treble Info App
1. Install "Treble Info" from Play Store
2. Open app
3. Check if "Treble" shows ✓
Method 2: Terminal
adb shell getprop ro.treble.enabled
# true = supported
Not All Treble Devices Are Equal
| Property | Meaning |
|---|---|
| A/B Partitions | Seamless updates support |
| A-only | Traditional partitions |
| System-as-Root (SAR) | Modern partition layout |
| Legacy | Old partition layout |
Check with Treble Info app - it shows your exact type.
GSI Types Explained
When downloading GSI, you'll see naming like:
system-quack-arm64-aonly-vanilla.img
Architecture
| Type | Devices |
|---|---|
| arm64 | Most modern phones (64-bit) |
| arm | Older 32-bit devices |
| x86_64 | Some tablets, VMs |
Most users need arm64.
Partition Type
| Type | Check With |
|---|---|
| aonly | A-only partitions |
| ab | A/B partitions |
Use Treble Info to determine yours.
GApps Inclusion
| Type | Meaning |
|---|---|
| vanilla | No Google Apps |
| gapps | Google Apps included |
| floss | Free/open source alternatives |
Where to Get GSIs
Official/Trusted Sources
PHH-Treble (Most Popular)
- GitHub: phhusson/treble_experimentations
- Well-maintained, frequently updated
- Best compatibility
Other Popular GSIs
- LineageOS GSI
- Pixel Experience GSI
- Evolution X GSI
- crDroid GSI
Checking Compatibility
Before downloading:
- Note your device's architecture (arm64, arm)
- Note your partition type (A, A/B)
- Note if SAR or Legacy
- Download matching GSI type
Step-by-Step Installation
Step 1: Backup Everything
1. TWRP → Backup → Boot, System, Vendor, Data
2. Store backup safely
Step 2: Unlock Bootloader
If not already:
adb reboot bootloader
fastboot flashing unlock
# Confirm on device
Step 3: Disable Verity & Verification
# Boot to fastboot
adb reboot bootloader
# Disable verification (if required)
fastboot flash vbmeta vbmeta.img --disable-verification --disable-verity
You may need vbmeta.img from your stock firmware.
Step 4: Flash GSI
Via Fastboot (Recommended)
# Boot to fastboot
adb reboot bootloader
# Delete existing system content
fastboot erase system
# Flash GSI
fastboot flash system your-gsi-file.img
# Wipe data
fastboot -w
# Reboot
fastboot reboot
Via TWRP
1. Wipe → Advanced → System, Data, Cache, Dalvik
2. Install → Install Image
3. Select GSI .img file
4. Select System partition
5. Swipe to flash
6. Reboot
Step 5: First Boot
First boot takes 5-10 minutes. Be patient!
If stuck on boot animation after 15 minutes:
- Boot to fastboot
- Reflash GSI
- Try different GSI version
PHH Treble Settings
PHH GSIs include special settings for device compatibility:
Access PHH Settings
Settings → Phh Treble Settings
Common Fixes Here
| Issue | Setting |
|---|---|
| Fingerprint not working | Enable vendor fingerprint |
| TouchScreen issues | Force alternate touchscreen |
| Display issues | Various display options |
| Audio issues | Audio settings section |
| Buttons not working | Button overrides |
Troubleshooting
Bootloop After Flash
1. Boot to fastboot
2. Flash different GSI version
3. Try fastboot -w before flash
No Mobile Data
PHH Settings → IMS features → Enable
Reboot
Fingerprint Not Working
PHH Settings → Fingerprint → Enable various options
Try each and reboot
Camera Not Working
Common issue with GSIs:
1. Try different camera app (Open Camera, GCam)
2. Check PHH Settings for camera options
3. Some features may not work on GSI
Display Issues
PHH Settings → Display
- Try different color profiles
- Enable/disable display options
- Force specific refresh rate
GSI Limitations
What Usually Works ✅
- Basic phone functionality
- WiFi
- Bluetooth (mostly)
- Display
- Audio
- Basic camera
What Often Has Issues ⚠️
- Fingerprint (device-specific)
- Advanced camera features
- NFC (sometimes)
- Specific hardware features
- VoLTE/VoWiFi
What Typically Doesn't Work ❌
- Vendor-specific features
- Some sensors
- Device-specific hardware
- IR blaster (usually)
Updating GSI
Method 1: Flash New Version
adb reboot bootloader
fastboot flash system new-gsi.img
fastboot reboot
No wipe needed for minor updates (usually).
Method 2: OTA (Some GSIs)
PHH GSI supports OTA updates via Settings.
Rooting GSI
With Magisk
Method 1: Patch Boot
1. Extract boot.img from GSI
2. Patch with Magisk
3. Flash patched boot
Method 2: Flash Magisk in TWRP
1. Boot to TWRP
2. Flash Magisk.zip
3. Reboot
Recovery on GSI
TWRP often works:
1. Download TWRP for your device
2. Flash via fastboot
3. Flash GSI, then flash Magisk
Custom Kernels with GSI
GSIs use your device's stock kernel. Custom kernels:
- May or may not work
- Must be for your specific device
- Not for the GSI itself
Best GSIs by Use Case
| Purpose | Recommended GSI |
|---|---|
| Stability | PHH Treble |
| Pixel features | Pixel Experience GSI |
| Customization | crDroid GSI |
| Minimal | LineageOS GSI |
| Testing | PHH Treble |
My GSI Experience
I've used GSIs on devices without official ROM support:
Pros experienced:
- Running latest Android on "unsupported" device
- Updates available faster than OEM
- Good basic functionality
Cons experienced:
- Camera never as good as device-specific ROM
- Some quirks require workarounds
- Fingerprint took effort to enable
Verdict: GSIs are amazing for devices without custom ROM support. For devices with good ROM support, device-specific ROMs are better.
When to Use GSI
Good Candidates ✅
- Device with no custom ROM support
- Testing latest Android features
- Old device you want to update
- Developers testing app compatibility
Not Ideal ❌
- Device has excellent ROM support
- Need perfect camera quality
- Need all hardware features
- Primary daily driver (unless comfortable troubleshooting)
Summary
Installing GSI:
1. Check Treble compatibility
2. Determine partition type (A/B vs A-only)
3. Download matching GSI
4. Flash to system partition
5. Boot and configure PHH settings
GSIs democratize custom ROM experience. Even if your device manufacturer abandoned it, Project Treble keeps it alive.
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