Plasma/Mobile/Porting

Current Architecture of Plasma Mobile

For ARM devices which requires Android binary blobs

• Kernel, either provided by vendor or thirdparty with config options enabled to support LXC containers
• AOSP/LineageOS base, built with core_tiny target, just base items
• LXC container with Neon/Ubuntu rootfs containing KWin/Wayland and Plasma Mobile

Kernel

Kernel needs to support the various config options, you can use lxc-checkconfig script provided by lxc userspace tools to check if all required features are enabled, for example:

% CONFIG=arch/arm64/configs/bullhead_defconfig lxc-checkconfig
--- Namespaces ---
Namespaces: enabled
Utsname namespace: enabled
Ipc namespace: enabled
Pid namespace: enabled
User namespace: enabled
Network namespace: missing
Multiple /dev/pts instances: enabled

--- Control groups ---
Cgroup: enabled
Cgroup clone_children flag: enabled
Cgroup device: enabled
Cgroup sched: enabled
Cgroup cpu account: enabled
Cgroup memory controller: enabled
Cgroup cpuset: enabled

[..]

Below is the list of the config options,

CONFIG_CGROUP_DEVICE=y
CONFIG_CPUSETS=y
CONFIG_CGROUP_MEM_RES_CTLR=y
CONFIG_CGROUP_PERF=y
CONFIG_UTS_NS=y
CONFIG_IPC_NS=y
CONFIG_USER_NS=y
CONFIG_PID_NS=y
CONFIG_DEVPTS_MULTIPLE_INSTANCES=y

AOSP/LineageOS base

AOSP/LineageOS base should have all non-required things removed and some changes in base to accomodate needs of libhybris and container containing Linux system. Below is list of various changes,

Export PATH and LD_LIBRARY_PATH to point to lxc userspace tools

We use prebuilt lxc userspace tools from linux containers CI. Those are installed in /data partition which by default is not in the PATH android shell looks binaries into. Modify the system/core/rootdir/init.environ.rc file to include the path of LXC userspace tools in $PATH and export LD_LIBRARY_PATH.

project system/core/
diff --git a/rootdir/init.environ.rc.in b/rootdir/init.environ.rc.in
index c32337a..9d91d60 100644
--- a/rootdir/init.environ.rc.in
+++ b/rootdir/init.environ.rc.in
@@ -1,6 +1,6 @@
 # set up the global environment
 on init
-    export PATH /sbin:/vendor/bin:/system/sbin:/system/bin:/system/xbin
+    export PATH /data/lxc/lxc/bin:/sbin:/vendor/bin:/system/sbin:/system/bin:/system/xbin
     export ANDROID_BOOTLOGO 1
     export ANDROID_ROOT /system
     export ANDROID_ASSETS /system/app
@@ -8,6 +8,7 @@ on init
     export ANDROID_STORAGE /storage
     export ASEC_MOUNTPOINT /mnt/asec
     export LOOP_MOUNTPOINT /mnt/obb
+    export LD_LIBRARY_PATH /data/lxc/lxc/lib
     export BOOTCLASSPATH %BOOTCLASSPATH%
     export SYSTEMSERVERCLASSPATH %SYSTEMSERVERCLASSPATH%
     export LD_PRELOAD libsigchain.so%TARGET_LDPRELOAD%

However, LD_LIBRARY_PATH doesn't work for AOSP based android image and needs investigation. See phabricator task for more details.

For devices which don't require Android binary blobs

• Normal Linux system with kernel and drivers supporting Wayland
• KWin/Wayland and Plasma Mobile packages