A local copy of OpenSSL from GitHub
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  1. NOTES FOR ANDROID PLATFORMS
  2. ===========================
  3. Requirement details
  4. -------------------
  5. Beside basic tools like perl and make you'll need to download the Android
  6. NDK. It's available for Linux, Mac OS X and Windows, but only Linux
  7. version was actually tested. There is no reason to believe that Mac OS X
  8. wouldn't work. And as for Windows, it's unclear which "shell" would be
  9. suitable, MSYS2 might have best chances. NDK version should play lesser
  10. role, the goal is to support a range of most recent versions.
  11. Configuration
  12. -------------
  13. Android is a naturally cross-compiled target and you can't use ./config.
  14. You have to use ./Configure and name your target explicitly; there are
  15. android-arm, android-arm64, android-mips, android-mip64, android-x86
  16. and android-x86_64 (*MIPS targets are no longer supported with NDK R20+).
  17. Do not pass --cross-compile-prefix (as you might be tempted), as it will
  18. be "calculated" automatically based on chosen platform. Though you still
  19. need to know the prefix to extend your PATH, in order to invoke
  20. $(CROSS_COMPILE)clang [*gcc on NDK 19 and lower] and company. (Configure
  21. will fail and give you a hint if you get it wrong.) Apart from PATH
  22. adjustment you need to set ANDROID_NDK_ROOT environment to point at the
  23. NDK directory. If you're using a side-by-side NDK the path will look
  24. something like /some/where/android-sdk/ndk/<ver>, and for a standalone
  25. NDK the path will be something like /some/where/android-ndk-<ver>.
  26. Both variables are significant at both configuration and compilation times.
  27. The NDK customarily supports multiple Android API levels, e.g. android-14,
  28. android-21, etc. By default latest API level is chosen. If you need to
  29. target an older platform pass the argument -D__ANDROID_API__=N to Configure,
  30. with N being the numerical value of the target platform version. For example,
  31. to compile for Android 10 arm64 with a side-by-side NDK r20.0.5594570
  32. export ANDROID_NDK_ROOT=/home/whoever/Android/android-sdk/ndk/20.0.5594570
  33. PATH=$ANDROID_NDK_ROOT/toolchains/llvm/prebuilt/linux-x86_64/bin:$ANDROID_NDK_ROOT/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64/bin:$PATH
  34. ./Configure android-arm64 -D__ANDROID_API__=29
  35. make
  36. Older versions of the NDK have GCC under their common prebuilt tools directory, so the bin path
  37. will be slightly different. EG: to compile for ICS on ARM with NDK 10d:
  38. export ANDROID_NDK_ROOT=/some/where/android-ndk-10d
  39. PATH=$ANDROID_NDK_ROOT/toolchains/arm-linux-androideabi-4.8/prebuilt/linux-x86_64/bin:$PATH
  40. ./Configure android-arm -D__ANDROID_API__=14
  41. make
  42. Caveat lector! Earlier OpenSSL versions relied on additional CROSS_SYSROOT
  43. variable set to $ANDROID_NDK_ROOT/platforms/android-<api>/arch-<arch> to
  44. appoint headers-n-libraries' location. It's still recognized in order
  45. to facilitate migration from older projects. However, since API level
  46. appears in CROSS_SYSROOT value, passing -D__ANDROID_API__=N can be in
  47. conflict, and mixing the two is therefore not supported. Migration to
  48. CROSS_SYSROOT-less setup is recommended.
  49. One can engage clang by adjusting PATH to cover same NDK's clang. Just
  50. keep in mind that if you miss it, Configure will try to use gcc...
  51. Also, PATH would need even further adjustment to cover unprefixed, yet
  52. target-specific, ar and ranlib. It's possible that you don't need to
  53. bother, if binutils-multiarch is installed on your Linux system.
  54. Another option is to create so called "standalone toolchain" tailored
  55. for single specific platform including Android API level, and assign its
  56. location to ANDROID_NDK_ROOT. In such case you have to pass matching
  57. target name to Configure and shouldn't use -D__ANDROID_API__=N. PATH
  58. adjustment becomes simpler, $ANDROID_NDK_ROOT/bin:$PATH suffices.
  59. Running tests (on Linux)
  60. ------------------------
  61. This is not actually supported. Notes are meant rather as inspiration.
  62. Even though build output targets alien system, it's possible to execute
  63. test suite on Linux system by employing qemu-user. The trick is static
  64. linking. Pass -static to Configure, then edit generated Makefile and
  65. remove occurrences of -ldl and -pie flags. You would also need to pick
  66. API version that comes with usable static libraries, 42/2=21 used to
  67. work. Once built, you should be able to
  68. env EXE_SHELL=qemu-<arch> make test
  69. If you need to pass additional flag to qemu, quotes are your friend, e.g.
  70. env EXE_SHELL="qemu-mips64el -cpu MIPS64R6-generic" make test