How to force Android application to use either 32bit or 64 bit libraries

Question

On a Android device with 64bit ARM, would have two variants of many libraries, 32bit and 64 bit, and their performance could be different. I want to know if there is a way to force the application to use either 32bit or 64bit libraries.

Answer 1

1. If your apk is written in pure java (without jni), on 64-bit-primiary/32-bit-secondary Android OS, your app will always run in 64 bit mode by default, but if you want your app to run in 32 bit mode, you can create a dummy *.so file and put it under <your apk name>/libs/armeabi/ to force AndroidRuntime to create a 32 bit VM for your app

2. If some function of your apk is written in jni (there's any *.so file in <your apk name>/libs/ folder), you can use following command to make it run in 64 or 32 bit VM：

   • To run in 32 bit mode, because only 32 bit native libs will be installed

   adb shell install --abi armeabi-v7a <path to your apk>

   • To run in 64 bit mode, because only 64 bit native libs will be installed

   adb shell install --abi arm64-v8a <path to your apk>

Answer 2

ABI can be specified when the apk is installed.

adb install --abi <path to apk>

In case ARM device,

To run in 32 bit mode install using,

adb install --abi armeabi-v7a <path to apk>

To run in 64 bit mode install using,

adb install --abi arm64-v8a <path to apk>

Answer 3

https://source.android.com/source/64-bit-builds.html

Try this in you Android.mk

LOCAL_MULTILIB := 32 // or 64