Running CMake from command line within an Android NDK project

Question

How might one run an NDK Cmake build independently from the rest of an Android project, ideally from the command line, external to Android Studio?

The equivalent of running ndk-build from the jni directory for slightly older Android NDK projects.

I need to investigate exactly what the calls to the compiler look like, and I can't seem to get this information when building the whole project from within Android Studio

My first attempt was just to run cmake from the project/app directory containing CMakeLists.txt, but this informs me that cmake is not installed - so how is Android Studio managing to build it then?

ok - have now found the Android/Sdk/cmake/3.6.3155560/bin directory - making progress.. — bph
– bph, Commented Jun 21, 2017 at 9:58
This is a relevant and useful resource -> developer.android.com/ndk/guides/cmake.html#build-command — bph
– bph, Commented Jun 21, 2017 at 11:11
This may be relevant to what you're trying to do, although it's not the same as your question: stackoverflow.com/questions/46530158/… — James Moore
– James Moore, Commented Nov 14, 2017 at 20:16

Dan Albert · Accepted Answer · 2017-06-22 19:11:14Z

15

If your goal is to just run from the command line (as opposed to trying to do exactly what gradle is doing), just use cmake the way you normally would:

$ cmake -DCMAKE_TOOLCHAIN_FILE=$NDK/build/cmake/android.toolchain.cmake \
    -DANDROID_ABI=whatever $YOUR_SOURCE_DIR

Alternatively, you can just run ./gradlew from the command line.

answered Jun 22, 2017 at 19:11

Dan Albert

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2 Comments

bph Over a year ago

this is correct, but I discovered that the way to inspect the clang compiler calls was to step one level deeper and run the build.ninja files with the -v option

Alex Cohn Over a year ago

-DANDROID_PLATFORM=android-XXX may also be necessary, where XXX is 21, or 16, or whatever you need.

Sai · Accepted Answer · 2025-03-19 18:27:23Z

5

Your original problem is that you cannot see the command-line invocation when building with Android Studio.

You can get the command line arguments to the compiler by editing your app/build.gradle file.

defaultConfig {
    ...
    externalNativeBuild {
        cmake {
            ...
            arguments "-DCMAKE_VERBOSE_MAKEFILE=1", ...
        }
    }

}

In Adroid Studio's Gradle Console pane, you will then see the command line for the compiler and linker like so:

[1/176] /home/bram/android-sdk-linux/ndk-bundle/toolchains/llvm/prebuilt/linux-x86_64/bin/clang  --target=armv7-none-linux-androideabi --gcc-toolchain=/home/bram/android-sdk-linux/ndk-bundle/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64 --sysroot=/home/bram/android-sdk-linux/ndk-bundle/sysroot   -isystem /home/bram/android-sdk-linux/ndk-bundle/sysroot/usr/include/arm-linux-androideabi -D__ANDROID_API__=19 -g -DANDROID -ffunction-sections -funwind-tables -fstack-protector-strong -no-canonical-prefixes -march=armv7-a -mfloat-abi=softfp -mfpu=vfpv3-d16 -fno-integrated-as -marm -mfpu=neon -Wa,--noexecstack -Wformat -Werror=format-security  -Os -DNDEBUG  -fPIC -MD -MT /home/bram/src/GPGOAP/CMakeFiles/gpgoap.dir/astar.c.o -MF /home/bram/src/GPGOAP/CMakeFiles/gpgoap.dir/astar.c.o.d -o /home/bram/src/GPGOAP/CMakeFiles/gpgoap.dir/astar.c.o   -c /home/bram/src/GPGOAP/astar.c

edited Mar 19 at 18:27

Sai

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answered Jun 22, 2017 at 21:38

Bram

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2 Comments

bph Over a year ago

this is interesting as I did add set(CMAKE_VERBOSE_MAKEFILE on) to my CMakeLists.txt instead of the build.gradle file but it didn't seem to do anything. I assume that both approaches should effectively achieve the same end? I'll go back and double check..

Lothar Over a year ago

Add a syntax error into your CMakeList.txt file and Android Studio shows you the command line invokation. But not the cmake output :-(

David · Accepted Answer · 2019-04-09 09:49:36Z

3

As detail to the accepted answer:

The complete set of parameters passed to CMake is written to:

<project-root>/<module-root>/.externalNativeBuild/cmake/<build-type>/<ABI>/cmake_build_command.txt`

See for details: https://developer.android.com/ndk/guides/cmake.html#build-command

edited Apr 9, 2019 at 9:49

David

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answered Apr 9, 2019 at 9:01

Stefan Densow

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