Ch'Gans random bits and bobs

The Open Source part of Android (AOSP) provides an ARM and x86 emulator based on QEMU. When you install Android SDK (via Android Studio or not), you can download a bunch of system images for the emulator. The google’s images allow you to run ARM APKs inside an x86_64 images. The technology is called Native Bridge/NDK translation.

I do not know how this works (yet), but i wanted to share with you how you can build your own emulator images with this proprietary technology.

Warning: This might not be legal, I’m just providing a Proof of Concept, for educational purpose.

The first thing to do is to boot up a Google emulator image, I have used this one:

Pkg.Desc=System Image x86 with Google APIs.
Pkg.Revision=9
Pkg.Dependencies=emulator#30.0.4                                                                                                                
AndroidVersion.ApiLevel=30
SystemImage.Abi=x86
SystemImage.TagId=google_apis
SystemImage.TagDisplay=Google APIs
SystemImage.GpuSupport=true
Addon.VendorId=google
Addon.VendorDisplay=Google Inc.

NDK translation uses the ‘binfmt_misc’ Linux capability to execute ARM binaries inside an x86 emulator. It supports ARM Android executable as well as shared object (APKs).

For ARM32 & ARM 64 support you need to pull:

bin/arm/
bin/arm64/
etc/binfmt_misc/arm_*
etc/binfmt_misc/arm64_*
etc/init/ndk_translation.rc
etc/init/ndk_translation_arm64.rc
etc/ld.config.arm.txt
etc/ld.config.arm64.txt
lib/arm/
lib/libndk_translation*.so
lib64/arm64/
lib64/libndk_translation*.so

Once you have all the files added to your tree, you then need to install them on the target and configure and enable the native bridge as shown below:

#
# ARM and ARM64 on x86_64 native bridge
# Based on proprietary binaries found in the system images of the Android SDK
#

PRODUCT_PROPERTY_OVERRIDES += \
    ro.dalvik.vm.isa.arm=x86 \
    ro.dalvik.vm.isa.arm64=x86_64 \
    ro.enable.native.bridge.exec=1 \
    ro.dalvik.vm.native.bridge=libndk_translation.so

PRODUCT_COPY_FILES += \
	$(call find-copy-subdir-files,*,$(LOCAL_PATH)/google-ndk-translation,$(TARGET_COPY_OUT_SYSTEM))

Et voilà! You can now install ARM and ARM64 APK in the emulator.

Will eventually follows up…

This post was written (quickly) for sharing with the android-x86 google group and the new AndroidEmu discord channel.