NDK Project Building Overview

By default, the OpenHarmony NDK uses CMake as the build system. To simplify your configuration process, the NDK provides the configuration file ohos.toolchain.cmake that complies with the OpenHarmony toolchain to predefine CMake variables.

You can build your project with the NDK in the following modes:

This section uses examples to describe how to use the NDK in a native project and how to write a CMake script to build a project with the NDK.

Introduction to ohos.toolchain.cmake

ohos.toolchain.cmake is the toolchain script provided by the OpenHarmony NDK for CMake. It predefines the build parameters that need to be set for building OpenHarmony applications, such as the target of the cross compilation device and the link mode of C++ runtime libraries. These parameters can be passed in by running CMake commands to change the default compilation and linking behavior. The following table lists the common parameters in this file.

Name Type Description
OHOS_STL c++_shared/c++_static Link mode of libc++.
Default value: c++_shared
Available options are as follows:
c++_shared: The native library dynamically links libc++_shared.so.
c++_static: The native library links the static library libc++_static.a.
Because some global variables are involved during C++ runtime, all native libraries must be linked to your application in the same mode.
OHOS_ARCH armeabi-v7a/arm64-v8a/x86_64 Target architecture for native cross compilation. Available options are as follows: armeabi-v7a, arm64-v8a, and x86_64.
OHOS_PLATFORM OHOS Target platform. Currently, only OpenHarmony is supported.

The preceding parameters control the cross compilation commands of Clang and generate proper command parameters.

  • The --target={arch}-linux-ohos parameter instructs the compiler to generate binary files that comply with OpenHarmony ABI in the corresponding architecture.

  • The --sysroot={ndk_root}/sysroot parameter notifies the compiler of the location of the OpenHarmony header files.