# Guide of Lindroid
## What is Lindroid?
Lindroid is an Android app that lets you run Linux in a container, with support for hardware-acceleration.
Official group: https://t.me/linux_on_droid

## How to Compile Lindroid?
1. Ensure your device has the necessary configurations:
   - Obtain a usable device configuration, kernel source, and ROM source code for your device.

2. Clone the necessary repositories [Linux-on-droid repository](https://github.com/Linux-on-droid):
   - Clone `vendor_lindroid` from to `$ANDROID_BUILD_TOP/vendor/lindroid`.
   - Clone `external_lxc` to `$ANDROID_BUILD_TOP/external/lxc`.
   - Clone `libhybris` (use the staging/lindroid-20 branch) to `$ANDROID_BUILD_TOP/libhybris`.
   - Cherry-pick or am/apply the patch from [this commit](https://github.com/Linux-on-droid/platform_system_core/commit/cb644190eeb9fefc3959a01dbdb83d89873e0b73) to `$ANDROID_BUILD_TOP/system/core`.

3. Modify device configurations:
   - Add `$(call inherit-product, vendor/lindroid/lindroid.mk)` to your device's mk file.
   - Add `BOARD_KERNEL_CMDLINE += androidboot.selinux=permissive` or `BOARD_BOOTCONFIG += androidboot.selinux=permissive` for GKI devices to BoardConfig.mk.
   - Ensure SELinux is set to permissive mode for Lindroid.

4. Kernel configuration:
   - For non-GKI devices, refer to kernel configurations for enabling LXC/Docker support.(Search keywords 'lxc docker android' in GitHub)
Make sure to add `CONFIG_VT=y`.
   - Example kernel configurations provided by Lindroid developers include:
     ```
     +CONFIG_SYSVIPC=y
     +CONFIG_UTS_NS=y
     +CONFIG_PID_NS=y
     +CONFIG_IPC_NS=y
     +CONFIG_USER_NS=y
     +CONFIG_NET_NS=y
     +CONFIG_CGROUP_DEVICE=y
     +CONFIG_KERNEL_CGROUP_FREEZER=y (likely `CONFIG_CGROUP_FREEZER`)
     ```
   - For GKI 5.10, refer to this [source](https://github.com/lateautumn233/Common-Android-Kernel-Tree/tree/lxc) and ensure `CONFIG_VT=y`. For 5.15 and 6.1, explore the configurations accordingly.
   - I recommend that compile KernelSU simultaneously for root access (use v0.9.5 tag for non-GKI). Or use magisk etc.

5. Build your ROM using the userdebug variant:
   - Avoid using user variant for now. 
   - If FCM (Framework Compatibility Matrix) errors occur, leading to OTA package build failure, manually build images (make systemimage vendorimage productimage bootimage ...) and flash them using fastboot in fastbootd.

## How to Use Lindroid?
1. Download and prepare the root filesystem
   - Download the pre-packaged Debian image from [Lindroid website](https://lindroid.org/lindroid.tar.gz).
   - Push it to /data/data/org.lindroid.ui/files/rootfs.tar.gz (rename to rootfs).
   - Open Lindroid and follow the prompts to create the container.

2. Configure your device
   - Ensure network connection, disable auto-rotate, set screen timeout to 30 minutes, and grant root access to shell in developer options.
   - Use adb shell or terminal to enter:
     ```shell
     su
     lxc_ls
     lxc_attach default
     /bin/bash -c "source /etc/profile && exec su - root"
     ```
   - Optionally, change Debian source mirrors for CN users: `sed -i 's/deb.debian.org/mirrors.bfsu.edu.cn/g' /etc/apt/sources.list`
   - Then upgrade all packages (Especially Kwin etc. from lindroid)
     ```shell
     apt update && apt-get -o Dpkg::Options::="--force-overwrite" full-upgrade
     ```
3. Test and configure the graphical interface:
   - Test graphics with `test_hwcomposer`.
   - Start or restart SDDM service:
     ```shell
     systemctl restart sddm
     ```
   - If touch doesn't work, try:
     ```shell
     sudo setcap cap_dac_read_search+ep /usr/bin/startplasma-wayland
     sudo setcap cap_dac_read_search+ep /usr/bin/kwin_wayland
     sudo setcap cap_dac_read_search+ep /usr/bin/sddm
     ```
   - Use evtest to check for Lindroid virtual input devices. Adjust /dev/uinput permissions if needed and restart Lindroid in adb shell.
     ```shell
     chmod 777 /dev/uinput
     am force-stop org.lindroid.ui
     ```
## Notes:
- Subsequent usage may encounter touch issues; restart Lindroid and SDDM as needed.
- Use `plasma-settings` instead of `system-settings` for now.
- External keyboard/mouse is recommended. KDE Connect can help with remote control.
- Strongly suggest SSH for better terminal experience.

This guide is a compilation of my personal exploration and guidance from Lindroid developers [Erfan Abdi, Luka, Nick].

Expect some initial issues, but it’s a promising start. Explore further on your own.