NOTE: OneLineage is just a proof of concept, this repo should provide you with enough to port other roms to bootloader locked devices, the lineageos with this repo is just a demo of this capability, and therefore does not fully work. Have fun!

Hot-switch between stock One UI and a LineageOS 23.2 (Android 16) GSI on a rooted Samsung phone, with no reflashing and no second partition. OneLineage stages the GSI under /data/local/tmp, pivots into it as a container with its own zygote and system_server, and can hand the screen back to One UI.

Disclaimer

This has been tested on only a handful of devices, and it seems if you want to install it without making modifications, it has to be on Android 16 It may not work on other Samsung models, other One UI versions, or other devices at all. It is experimental, it replaces core parts of a running system, and it can crash, hang or soft-brick your phone, fill /data, or break radio/SMS. Back up everything first. Use at your own risk. Also, I did use AI a fair bit in this project, it would have taken a LOT longer without it.

• A rooted Samsung phone (the tested one is an S26 Ultra on One UI 8.5)
• Enough free space on /data for the extracted GSI
• Internet access for the GSI download (LineageOS 23.2 GSI, EXT4, VANILLA or GAPPS builds from SourceForge)

• services_patched.jar over system/framework/services.jar
• framework_patched.jar over system/framework/framework.jar
• PermissionController_patched.apk: removes the android.permission.RANGING reference so runtime-permission dialogs stop crashing (Samsung's PermissionController needs a permission the LineageOS 23.2 platform doesn't define)
• Optional bind-mounts when present: framework-res_patched.apk, libaudio_aidl_conversion_common_cpp_patched.so, libaudioclient_aidl_conversion_patched.so

1. APEX paths in the container. Host /system/apex and /system_ext/apex are bound into the rootfs after the GSI payloads are extracted, so PackageManagerService stops dying in scanApexPackages.
2. SELinux labels on the staged /data. The tree is relabeled like a real /data (system_data_file, per-package app_data_file) instead of shell_data_file. Also setenforce 0 during the takeover and setenforce 1 on return.
3. Audio hang. Host audioserver/cameraserver are left running (they used to be stopped/frozen, which deadlocked AudioService). Only the host zygote is suppressed.
4. Runaway sf.log. SurfaceFlinger output goes to /dev/null (it was growing to hundreds of MB in minutes).
5. App data ownership. fix_app_dirs.sh re-owns app data dirs to the uid PackageManager assigned, strips write bits from dex/apk/jar files (ART refuses writable dex), and creates missing dirs such as /data/misc/bluedroid.
6. No installd. ensure_app_storage.sh plus a 15 s sweeper create /data/user/0, /data/user_de/0 and shared-storage dirs for new installs, so apps installed inside Lineage can launch.
7. Gesture navigation. Overlay idmaps are generated with idmap2 --ignore-overlayable before zygote starts.
8. Bluetooth crash loop fixed by creating /data/misc/bluedroid before boot.
9. adb. Settings.Global.ADB_ENABLED is pre-seeded, host adb_keys are copied into the guest, and adb_watchdog.sh keeps adbd and the USB gadget alive.
10. Networking. The preferred APN is switched to IPV4V6, and net_fix.sh maintains a private routing table (4242) because the guest's ConnectivityService can't program the host's netd.
11. SMS. ims_watchdog.sh keeps One UI's imsd running and switch_to_lineage.sh waits for voice registration before pivoting.
12. Boot diagnostics. Each boot writes /data/boot_failures.log.

• Returning to One UI may still need a manual reboot.
• The guest binds the host's media.codec, whose AIDL hash differs from the GSI's, which can cause high CPU during codec enumeration.
• No IMS stack in the guest, so voice calls don't work (data and SMS depend on One UI's imsd).
• Developer options crash (the guest registers no adb service).
• DTMF tones glitch, and deep-buffer audio hangs, so it stays disabled.
• Never kill the host netd while Lineage is running.

Edit the paths at the top of build_apk.sh (JDK 17, Android SDK build-tools 34, android-34 platform), provide your own signing keystore, then run ./build_apk.sh.

LineageOS GSI builds by MisterZtr (SourceForge). LineageOS and Android are trademarks of their respective owners. Not affiliated with Samsung, Google or LineageOS.