android_packages_modules_Virtualization/microdroid

Microdroid

Microdroid is a (very) lightweight version of Android that is intended to run on on-device virtual machines. It is built from the same source code as the regular Android, but it is much smaller; no system server, no HALs, no GUI, etc. It is intended to host headless & native workloads only.

Building

You need a VIM3L board. Instructions for building Android for the target, and flashing the image can be found here.

Then you build microdroid. Note that the instruction below is very likely to change in the future, because this is in active development. For example, the microdroid_* modules will eventually be included in the com.android.virt APEX, which is already in the yukawa (VIM3L) target.

$ source build/envsetup.sh
$ choosecombo 1 aosp_arm64 userdebug // actually, any arm64-based target is ok
$ m microdroid_super
$ m microdroid_boot-5.10
$ m microdroid_vendor_boot-5.10
$ m microdroid_uboot_env
$ m microdroid_vbmeta
$ m microdroid_vbmeta_system

Installing

Push the built files to the device. In addition to that, some other files have to be manually created, for now. In the future, you won't need these.

$ adb push device/google/cuttlefish_prebuilts/bootloader/crosvm_aarch64/u-boot.bin /data/local/tmp/bootloader
$ adb push $ANDROID_PRODUCT_OUT/system/etc/microdroid_super.img /data/local/tmp/super.img
$ adb push $ANDROID_PRODUCT_OUT/system/etc/microdroid_boot-5.10.img /data/local/tmp/boot.img
$ adb push $ANDROID_PRODUCT_OUT/system/etc/microdroid_vendor_boot-5.10.img /data/local/tmp/vendor_boot.img
$ adb push $ANDROID_PRODUCT_OUT/system/etc/microdroid_vbmeta.img /data/local/tmp/vbmeta.img
$ adb push $ANDROID_PRODUCT_OUT/system/etc/microdroid_vbmeta_system.img /data/local/tmp/vbmeta_system.img
$ adb shell mkdir /data/local/tmp/cuttlefish_runtime.1/
$ adb push $ANDROID_PRODUCT_OUT/system/etc/uboot_env.img /data/local/tmp/cuttlefish_runtime.1/
$ adb shell mkdir -p /data/local/tmp/etc/cvd_config
$ adb shell 'echo "{}" > /data/local/tmp/etc/cvd_config/cvd_config_phone.json'
$ dd if=/dev/zero of=empty.img bs=4k count=600
$ mkfs.ext4 -F empty.img
$ adb push empty.img /data/local/tmp/userdata.img
$ adb push empty.img /data/local/tmp/cache.img

Running

Create the composite image using assemble_cvd and run it via crosvm. In the future, this shall be done via virtmanager.

$ adb shell 'HOME=/data/local/tmp; PATH=$PATH:/apex/com.android.virt/bin; assemble_cvd -protected_vm < /dev/null'
$ adb shell 'cd /data/local/tmp; /apex/com.android.virt/bin/crosvm run --cid=5 --disable-sandbox --bios=bootloader --serial=type=stdout --disk=cuttlefish_runtime/os_composite.img'

The CID in --cid parameter can be anything greater than 2 (VMADDR_CID_HOST).

ADB

$ adb forward tcp:8000 vsock:5:5555
$ adb connect localhost:8000

5 in vsock:5 should match with the CID number that was given to crosvm. 5555 must be the value. 8000 however can be any port in the development machine.

Done. Now you can log into microdroid. Have fun!

$ adb -s localhost:8000 shell