I am working on build a c library for android 5.1.1. 
First I build a standalone toolchain by following the  [google ndk standalone toolchain guild](https://developer.android.com/ndk/guides/standalone_toolchain.html).  

```
<prebuilt_ndk_r12b_path>/build/tools/make-standalone-toolchain.sh --platform=android-22 --ndk-dir=<prebuilt_ndk_r12b_path> --install-dir=/home/r0ng/utilities/ndk --toolchain=x86_64-linux-android-4.9

```

After that, I exported CC, AR and RANLIB in ~/.bashrc

```
export ANDROID_NDK=/home/r0ng/utilities/ndk
SYSROOT=$ANDROID_NDK/sysroot

export CC="$ANDROID_NDK/bin/arm-linux-androideabi-gcc-4.9.x --sysroot=$SYSROOT"
export AR="$ANDROID_NDK/bin/arm-linux-androideabi-gcc-ar --sysroot=$SYSROOT"
export RANLIB="$ANDROID_NDK/bin/arm-linux-androideabi-gcc-ranlib --sysroot=$SYSROOT"

```

But when I tried to compile by using `cmake ..`. I had the following errors:

```
-- The C compiler identification is GNU 4.9.0
-- The CXX compiler identification is GNU 4.9.3
-- Check for working C compiler: /home/r0ng/utilities/ndk/bin/arm-linux-androideabi-gcc
-- Check for working C compiler: /home/r0ng/utilities/ndk/bin/arm-linux-androideabi-gcc -- broken
CMake Error at /usr/share/cmake-3.5/Modules/CMakeTestCCompiler.cmake:61 (message):
  The C compiler "/home/r0ng/utilities/ndk/bin/arm-linux-androideabi-gcc" is
  not able to compile a simple test program.

  It fails with the following output:

   Change Dir: /home/r0ng/projects/relic/build/CMakeFiles/CMakeTmp

  Run Build Command:"/usr/bin/make" "cmTC_8d7ca/fast"

  /usr/bin/make -f CMakeFiles/cmTC_8d7ca.dir/build.make
  CMakeFiles/cmTC_8d7ca.dir/build

  make[1]: Entering directory
  '/home/r0ng/projects/relic/build/CMakeFiles/CMakeTmp'

  Building C object CMakeFiles/cmTC_8d7ca.dir/testCCompiler.c.o

  /home/r0ng/utilities/ndk/bin/arm-linux-androideabi-gcc
  --sysroot=/home/r0ng/utilities/ndk -o
  CMakeFiles/cmTC_8d7ca.dir/testCCompiler.c.o -c
  /home/r0ng/projects/relic/build/CMakeFiles/CMakeTmp/testCCompiler.c

  Linking C executable cmTC_8d7ca

  /usr/bin/cmake -E cmake_link_script CMakeFiles/cmTC_8d7ca.dir/link.txt
  --verbose=1

  /home/r0ng/utilities/ndk/bin/arm-linux-androideabi-gcc
  --sysroot=/home/r0ng/utilities/ndk
  CMakeFiles/cmTC_8d7ca.dir/testCCompiler.c.o -o cmTC_8d7ca -rdynamic

  /home/r0ng/utilities/ndk/bin/../lib/gcc/arm-linux-androideabi/4.9.x/../../../../arm-linux-androideabi/bin/ld:
  error: cannot open crtbegin_dynamic.o: No such file or directory

  /home/r0ng/utilities/ndk/bin/../lib/gcc/arm-linux-androideabi/4.9.x/../../../../arm-linux-androideabi/bin/ld:
  error: cannot open crtend_android.o: No such file or directory

  /home/r0ng/utilities/ndk/bin/../lib/gcc/arm-linux-androideabi/4.9.x/../../../../arm-linux-androideabi/bin/ld:
  error: cannot find -lc

  /home/r0ng/utilities/ndk/bin/../lib/gcc/arm-linux-androideabi/4.9.x/../../../../arm-linux-androideabi/bin/ld:
  error: cannot find -ldl

  collect2: error: ld returned 1 exit status

  CMakeFiles/cmTC_8d7ca.dir/build.make:97: recipe for target 'cmTC_8d7ca'
  failed

  make[1]: *** [cmTC_8d7ca] Error 1

  make[1]: Leaving directory
  '/home/r0ng/projects/relic/build/CMakeFiles/CMakeTmp'

  Makefile:126: recipe for target 'cmTC_8d7ca/fast' failed

  make: *** [cmTC_8d7ca/fast] Error 2

  CMake will not be able to correctly generate this project.
Call Stack (most recent call first):
  CMakeLists.txt:6 (project)

-- Configuring incomplete, errors occurred!
See also "/home/r0ng/projects/relic/build/CMakeFiles/CMakeOutput.log".
See also "/home/r0ng/projects/relic/build/CMakeFiles/CMakeError.log".

```

It seems that the compiler is unable to find "crtbegin\_dynamic.o", "crtend\_android.o", "libc" neither "libdl". But when I checked, those files are all in the folder $HOME/utilities/ndk/sysroot/usr/lib. And I already set the --sysroot in CC, AR and RANLIB.

---

**Update 1 :**  

After changed the toolchain generation command based on Dan Albert's comment, The command `cmake ..` is able to be run successfully. But when I run `make .` I got following error:

```
arm-linux-androideabi-gcc-4.9.x: error: unrecognized command line option '-m64'
src/CMakeFiles/relic.dir/build.make:62: recipe for target 'src/CMakeFiles/relic.dir/relic_err.c.o' failed
make[2]: *** [src/CMakeFiles/relic.dir/relic_err.c.o] Error 1
CMakeFiles/Makefile2:120: recipe for target 'src/CMakeFiles/relic.dir/all' failed
make[1]: *** [src/CMakeFiles/relic.dir/all] Error 2
Makefile:138: recipe for target 'all' failed
make: *** [all] Error 2

```

Thanks,

---

**Environment:**  

* OS: Ubuntu 16.04 LTS
* gcc / g++: 4.9.3
* AOSP: 5.1.1\_r30
* NDK: android-ndk-r12b
* cmake: 3.5.1