1 ## 3.3\. Native API Compatibility 2 3 Native code compatibility is challenging. For this reason, 4 device implementers are: 5 6 * [SR] STRONGLY RECOMMENDED to use the implementations of the libraries 7 listed below from the upstream Android Open Source Project. 8 9 ### 3.3.1\. Application Binary Interfaces 10 11 Managed Dalvik bytecode can call into native code provided in the application 12 `.apk` file as an ELF `.so` file compiled for the appropriate device hardware 13 architecture. As native code is highly dependent on the underlying processor 14 technology, Android defines a number of Application Binary Interfaces (ABIs) in 15 the Android NDK. 16 17 Device implementations: 18 19 * [C-0-1] MUST be compatible with one or more defined ABIs and implement 20 compatibility with the Android NDK. 21 * [C-0-2] MUST include support for code running in the managed environment to 22 call into native code, using the standard Java Native Interface (JNI) 23 semantics. 24 * [C-0-3] MUST be source-compatible (i.e. header-compatible) and 25 binary-compatible (for the ABI) with each required library in the list 26 below. 27 * [C-0-4] MUST support the equivalent 32-bit ABI if any 64-bit ABI is 28 supported. 29 * [C-0-5] MUST accurately report the native Application Binary Interface 30 (ABI) supported by the device, via the `android.os.Build.SUPPORTED_ABIS`, 31 `android.os.Build.SUPPORTED_32_BIT_ABIS`, and 32 `android.os.Build.SUPPORTED_64_BIT_ABIS` parameters, each a comma separated 33 list of ABIs ordered from the most to the least preferred one. 34 * [C-0-6] MUST report, via the above parameters, only those ABIs documented 35 and described in the latest version of the 36 [Android NDK ABI Management documentation]( 37 https://developer.android.com/ndk/guides/abis.html), and MUST include 38 support for the [Advanced SIMD]( 39 http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.ddi0388f/Beijfcja.html) 40 (a.k.a. NEON) extension. 41 * [C-0-7] MUST make all the following libraries, providing native APIs, 42 available to apps that include native code: 43 44 * libaaudio.so (AAudio native audio support) 45 * libandroid.so (native Android activity support) 46 * libc (C library) 47 * libcamera2ndk.so 48 * libdl (dynamic linker) 49 * libEGL.so (native OpenGL surface management) 50 * libGLESv1\_CM.so (OpenGL ES 1.x) 51 * libGLESv2.so (OpenGL ES 2.0) 52 * libGLESv3.so (OpenGL ES 3.x) 53 * libicui18n.so 54 * libicuuc.so 55 * libjnigraphics.so 56 * liblog (Android logging) 57 * libmediandk.so (native media APIs support) 58 * libm (math library) 59 * libneuralnetworks.so (Neural Networks API) 60 * libOpenMAXAL.so (OpenMAX AL 1.0.1 support) 61 * libOpenSLES.so (OpenSL ES 1.0.1 audio support) 62 * libRS.so 63 * libstdc++ (Minimal support for C++) 64 * libvulkan.so (Vulkan) 65 * libz (Zlib compression) 66 * JNI interface 67 68 * [C-0-8] MUST NOT add or remove the public functions for the native libraries 69 listed above. 70 * [C-0-9] MUST list additional non-AOSP libraries exposed directly to 71 third-party apps in `/vendor/etc/public.libraries.txt`. 72 * [C-0-10] MUST NOT expose any other native libraries, implemented and 73 provided in AOSP as system libraries, to third-party apps targeting API 74 level 24 or higher as they are reserved. 75 * [C-0-11] MUST export all the OpenGL ES 3.1 and [Android Extension Pack]( 76 http://developer.android.com/guide/topics/graphics/opengl.html#aep) 77 function symbols, as defined in the NDK, through the `libGLESv3.so` library. 78 Note that while all the symbols MUST be present, section 7.1.4.1 describes 79 in more detail the requirements for when the full implementation of each 80 corresponding functions are expected. 81 * [C-0-12] MUST export function symbols for the core Vulkan 1.0 function 82 symobls, as well as the `VK_KHR_surface`, `VK_KHR_android_surface`, 83 `VK_KHR_swapchain`, `VK_KHR_maintenance1`, and 84 `VK_KHR_get_physical_device_properties2` extensions through the 85 `libvulkan.so` library. Note that while all the symbols MUST be present, 86 section 7.1.4.2 describes in more detail the requirements for when the full 87 implementation of each corresponding functions are expected. 88 * SHOULD be built using the source code and header files available in the 89 upstream Android Open Source Project 90 91 Note that future releases of the Android NDK may introduce support for 92 additional ABIs. 93 94 ### 3.3.2. 32-bit ARM Native Code Compatibility 95 96 If device implementations are 64-bit ARM devices, then: 97 98 * [C-1-1] Although the ARMv8 architecture deprecates several CPU operations, 99 including some operations used in existing native code, the following 100 deprecated operations MUST remain available to 32-bit native ARM code, 101 either through native CPU support or through software emulation: 102 103 * SWP and SWPB instructions 104 * SETEND instruction 105 * CP15ISB, CP15DSB, and CP15DMB barrier operations 106 107 If device implementations include a 32-bit ARM ABI, they: 108 109 * [C-2-1] MUST include the following lines in `/proc/cpuinfo` when it is read 110 by 32-bit ARM applications to ensure compatibility with applications built 111 using legacy versions of Android NDK. 112 113 * `Features: `, followed by a list of any optional ARMv7 CPU features 114 supported by the device. 115 * `CPU architecture: `, followed by an integer describing the device's 116 highest supported ARM architecture (e.g., "8" for ARMv8 devices). 117 118 * SHOULD not alter `/proc/cpuinfo` when read by 64-bit ARM or non-ARM 119 applications. 120
