NOTES.ANDROID

   1
   2  NOTES FOR ANDROID PLATFORMS
   3  ===========================
   4
   5  Requirement details
   6  -------------------
   7
   8  Beside basic tools like perl and make you'll need to download the Android
   9  NDK. It's available for Linux, Mac OS X and Windows, but only Linux
  10  version was actually tested. There is no reason to believe that Mac OS X
  11  wouldn't work. And as for Windows, it's unclear which "shell" would be
  12  suitable, MSYS2 might have best chances. NDK version should play lesser
  13  role, the goal is to support a range of most recent versions.
  14
  15  Configuration
  16  -------------
  17
  18  Android is naturally cross-compiled target and you can't use ./config.
  19  You have to use ./Configure and name your target explicitly; there are
  20  android-arm, android-arm64, android-mips, android-mip64, android-x86
  21  and android-x86_64. Do not pass --cross-compile-prefix (as you might
  22  be tempted), as it will be "calculated" automatically based on chosen
  23  platform. Though you still need to know the prefix to extend your PATH,
  24  in order to invoke $(CROSS_COMPILE)gcc and company. (Configure will fail
  25  and give you a hint if you get it wrong.) Apart from PATH adjustment
  26  you need to set ANDROID_NDK environment to point at NDK directory
  27  as /some/where/android-ndk-<ver>. NDK customarily supports multiple
  28  Android API levels, e.g. android-14, android-21, etc. By default latest
  29  one available is chosen. If you need to target older platform, pass
  30  additional -D__ANDROID_API__=N to Configure. N is numeric value of the
  31  target platform version. For example, to compile for ICS on ARM with
  32  NDK 10d:
  33
  34     ANDROID_NDK=/some/where/android-ndk-10d
  35     PATH=$ANDROID_NDK/toolchains/arm-linux-androideabi-4.8/prebuilt/linux-x86_64/bin:$PATH
  36     ./Configure android-arm -D__ANDROID_API__=14
  37
  38  Caveat lector! Earlier OpenSSL versions relied on additional CROSS_SYSROOT
  39  variable set to $ANDROID_NDK/platforms/android-<api>/arch-<arch> to
  40  appoint headers-n-libraries' location. It's still recognized in order
  41  to facilitate migration from older projects. However, since API level
  42  appears in CROSS_SYSROOT value, passing -D__ANDROID_API__=N can be in
  43  conflict, and mixing the two is therefore not supported. Migration to
  44  CROSS_SYSROOT-less setup is recommended.
  45
  46  One can engage clang by adjusting PATH to cover NDK's clang. Just keep
  47  in mind that if you miss it, Configure will try to use gcc... Also,
  48  PATH would need even further adjustment to cover unprefixed, yet
  49  target-specific, ar and ranlib (or not, if you use binutils-multiarch
  50  on your Linux).
  51
  52  Running tests (on Linux)
  53  ------------------------
  54
  55  This is not actually supported. Notes are meant rather as inspiration.
  56
  57  Even though build output targets alien system, it's possible to execute
  58  test suite on Linux system by employing qemu-user. The trick is static
  59  linking. Pass -static to Configure, then edit generated Makefile and
  60  remove occurrences of -ldl and -pie flags. You would also need to pick
  61  API version that comes with usable static libraries, 42/2=21 used to
  62  work. Once built, you should be able to
  63
  64     env EXE_SHELL=qemu-<arch> make test
  65
  66  If you need to pass additional flag to qemu, quotes are your friend, e.g.
  67
  68     env EXE_SHELL="qemu-mips64el -cpu MIPS64R6-generic" make test