In the Meson tutorial, we learned how to create a Meson package with a detailed guide. Since Cmake and Meson have similar roots, this tutorial will only focus on their differences.
To begin, let's create a CMake project. The main.c file for this project will be the same as the one in the Meson tutorial, which includes a single “Hello, World” program. However, in order to use CMake, we need to include a CMakeLists.txt file. The most basic CMake file is presented here for simplicity.
cmake_minimum_required(VERSION 3.1...3.27) project( hellocmake VERSION 1.0 LANGUAGES C) add_executable(hellocmake main.c) install(TARGETS hellocmake DESTINATION /usr/bin)
The Makefile is very similar to other OpenWrt-based makefiles. The only difference is that it includes cmake.mk instead of meson.mk:
include $(TOPDIR)/rules.mk PKG_NAME:=hellocmake PKG_VERSION:=0.1 PKG_RELEASE:=1 SOURCE_DIR:=/media/workspace/packages/cmakepackages/hellocmake PKG_BUILD_DIR:=$(BUILD_DIR)/hellocmake-$(PKG_VERSION) include $(INCLUDE_DIR)/package.mk include $(INCLUDE_DIR)/cmake.mk define Package/hellocmake CATEGORY:=custom TITLE:=Simple Cmake package #DEPENDS:=+libstdcpp +ixwebsocket +libatomic endef define Package/hellocmake/description hellocmake is a simple application to demonstrate OpenWrt build system with cmake packages endef define Package/hellocmake/install $(INSTALL_DIR) $(1)/usr/bin $(INSTALL_BIN) $(PKG_BUILD_DIR)/hellocmake $(1)/usr/bin/ endef $(eval $(call BuildPackage,hellocmake))
In order to pass Cmake options, we can use the following syntax in the Makefile
CMAKE_OPTIONS+= \ -D<OPTION>bool=OFF
For example:
CMAKE_OPTIONS+= \ -DBUILD_TESTING:bool=OFF
To enable this package, open the configuration menu by typing make menuconfig in the command line. From there, go to custom → hellocmake and select the package.
If everything goes smoothly, the package that is built will be located in <BIN_DIR>/packages/<target>/cmakepackages/.
For instance:
hellocmake_0.1-1_arm_cortex-a7_neon-vfpv4.ipk