1# Microdroid Demo app in C++
2
3This app is a demonstration of how to create a VM and run payload in it, in C++.
4
5## Restriction
6
7This is for VMs that are part of the platform itself. Specifically, this C++ example is for cases
8like creating and using a VM from a HAL process.
9
10For non-system-level VMs, you must use the Java APIs from an Android app. See the [Java demo
11app](../demo/README.md).
12
13## Building
14
15```sh
16source build/envsetup.sh
17choosecombo 1 aosp_arm64 userdebug
18m MicrodroidTestApp
19m vm_demo_native
20```
21
22`MicrodroidTestApp` is the application what will be running in the VM. Actually, we will run a
23native shared library `MicrodroidTestNativeLib.so` from the APK.
24
25`vm_demo_native` runs on the host (i.e. Android). Its job is to start the VM and connect to the
26native shared lib and do some work using the lib. Specifically, we will call an AIDL method
27`addInteger` which adds two integers and returns the sum. The computation will be done in the VM.
28
29## Installing
30
31```sh
32adb push out/target/product/generic_arm64/testcases/MicrodroidTestApp/arm64/MicrodroidTestApp.apk \
33  /data/local/tmp/
34adb push out/target/product/generic_arm64/system/bin/vm_demo_native /data/local/tmp/
35```
36
37## Running
38
39```sh
40adb root
41adb shell setenforce 0
42adb shell /data/local/tmp/vm_demo_native
43```
44
45Rooting and selinux disabling are required just because there's no sepolicy configured for this demo
46application. For production, you need to set the sepolicy up correctly. You may use
47`system/sepolicy/private/composd.te` (specifically, the macro `virtualizationservice_use`) as a
48reference.
49
50## Expected output
51
52```sh
53[2023-05-10T23:45:54.904181191+09:00 INFO  crosvm] crosvm started.
54[2023-05-10T23:45:54.906048663+09:00 INFO  crosvm] CLI arguments parsed.
55...
56The answer from VM is 30
57[    1.996707][   T57] microdroid_manager[57]: task successfully finished
58...
59[2023-05-10T23:45:58.263614461+09:00 INFO  crosvm] exiting with success
60Done
61```
62