I’ve been trying for a couple days to compile a native ARM Android binary that will execute on my phone using a terminal application. I want to generate the same type of binary as the standard Posix binaries installed on the phone like ls, mkdir etc. I’ve downloaded the Android NDK under Mac OS X and have been able to compile simple ELF binaries without errors. However, when I transfer them to the phone, they always segfault. That is, they segfault when compiled with -static in GCC. If I don’t use -static, they complain about not being linked, etc. Put simply, they don’t work.
My hypothesis is that they are not linking to the Android standard C library properly. Even though I am linking my binaries with the libc provided by the NDK, they still don’t work. I read that Android uses the Bionic C library, and tried to download source for it but I’m not sure how to build a library from it (it’s all ARM assembly, it seems).
Is it true that the Android C library on the phone is different from the one provided with the Android NDK? Will the one included with the NDK not allow me to compile native binaries I can execute through a terminal? Any guidance here is greatly appreciated!
I finally got this to work using GCC 4.7.0 on Mac OS X. I downloaded the Bionic headers and then compiled a dynamically linked binary using the C library that comes with the Android NDK. I was able to get a test app to work on the phone using the phone’s C lib (the binary was 33K). I also tried to statically link against the NDK’s C library, and that also worked.
In order to get this all working I had to pass -nostdlib to GCC and then manually add crtbegin_dynamic.o and crtend_android.o to GCC’s command line. It works something like this:
$CC \ $NDK_PATH/usr/lib/crtbegin_dynamic.o \ hello.c -o hello \ $CFLAGS \ $NDK_PATH/usr/lib/crtend_android.o
For static binaries, use “crtbegin_static.o.” This is explained in the crtbegin_dynamic.S/crtbegin_static.S source.
For this experiment, I only used plain ‘ol GCC 4.7.0 and Binutils 2.22. I also compiled GCC with newlib, but I am not actually linking my ARM binaries with newlib at all. I am forcing GCC/ld to link directly to the libc provided with the Android NDK, or in the case of dynamic binaries, to the libc on the phone.
Just use the android-ndk. And build a Android.mk like so.
include $(BUILD_EXECUTABLE) is what tells it build a executable instead of a JNI .lib
ifneq ($(TARGET_SIMULATOR),true) LOCAL_PATH:= $(call my-dir) include $(CLEAR_VARS) LOCAL_CFLAGS += -Wall LOCAL_LDLIBS := -L$(LOCAL_PATH)/lib -llog -g LOCAL_C_INCLUDES := bionic LOCAL_C_INCLUDES += $(LOCAL_PATH)/include LOCAL_SRC_FILES:= main.cpp LOCAL_MODULE := mycmd include $(BUILD_EXECUTABLE) endif # TARGET_SIMULATOR != true
First, make sure you have the NDK:
Here is the easiest way to compile a C binary for your phone:
Usually $NDK(may be different) =
Mac OS X:
# create tool-chain - one line # New method in ndk 12. $NDK/build/tools/make_standalone_toolchain.py --arch arm --install-dir=/tmp/my-android-toolchain # Old method. #$NDK/build/tools/make-standalone-toolchain.sh --platform=android-3 --install-dir=/tmp/my-android-toolchain # add to terminal PATH variable export PATH=/tmp/my-android-toolchain/bin:$PATH # make alias CC be the new gcc binary export CC=arm-linux-androideabi-gcc # compile your C code(I tried hello world) $CC -o foo.o -c foo.c # push binary to phone adb push foo.o /data/local/tmp # execute binary adb /data/local/tmp/foo.o
Using CMake with the Android NDK is a nice way to compile Android console applications.
project(test) cmake_minimum_required(VERSION 2.8) add_executable(test ./main.c)
cmake -DCMAKE_TOOLCHAIN_FILE=$ANDTOOLCHAIN .
You will then have a Makefile for your program, you can run
make to have your
Try if if the agcc wrapper can help you as referenced in the Android-tricks blog. According to the blog post you want to use the bionic library, but the one already installed on the phone, not some separately compiled version.