CMake-CPack组件化生成DEB包为空问题求助

我需要为IMX6/IMX8平台生成组件化DEB包，工具链会自动设置对应平台变量。使用IMX6时CPack输出如下：

Run CPack packaging tool...
CPack: Create package using DEB
CPack: Install projects
CPack: - Run preinstall target for: main_project
CPack: - Install project: main_project []
CPack: -   Install component: PRIMARY_DISPLAY
CPack: -   Install component: SECONDARY_DISPLAY
CPack: Create package
-- CPACK_DEBIAN_PACKAGE_DEPENDS not set, the package will have no dependencies.
-- CPACK_DEBIAN_PACKAGE_DEPENDS not set, the package will have no dependencies.
CPack: - package: /home/anzipex/Downloads/add_target_package_secondary_47154/debs_47154/unca_23/cmake-build-release-imx6/unca-1.0.1-Linux-PRIMARY_DISPLAY.deb generated.
CPack: - package: /home/anzipex/Downloads/add_target_package_secondary_47154/debs_47154/unca_23/cmake-build-release-imx6/unca-1.0.1-Linux-SECONDARY_DISPLAY.deb generated.

现在的问题是生成的DEB包为空，_CPack_Packages目录下的DEB包中，data.tar.gz仅包含空的usr目录。但设置set(CPACK_MONOLITHIC_INSTALL 1)后，主DEB包能包含所有数据，这是什么原因？

主项目CMakeLists.txt内容：

cmake_minimum_required(VERSION 3.0.0)

set(CPACK_GENERATOR "DEB")
set(CPACK_DEBIAN_PACKAGE_MAINTAINER "Company")
set(CPACK_PACKAGE_VERSION ${PROJECT_VERSION})
set(CPACK_DEB_COMPONENT_INSTALL ON)

if(NOT CMAKE_CROSSCOMPILING)
    set(CPACK_COMPONENTS_ALL DESKTOP)
    set(CPACK_DEBIAN_DESKTOP_PACKAGE_ARCHITECTURE "amd64")
    add_subdirectory(desktop)
elseif(IMX6)
    set(CPACK_COMPONENTS_ALL PRIMARY_DISPLAY SECONDARY_DISPLAY)
    set(CPACK_DEBIAN_PRIMARY_DISPLAY_PACKAGE_ARCHITECTURE "armhf")
    set(CPACK_DEBIAN_SECONDARY_DISPLAY_PACKAGE_ARCHITECTURE "armhf")
    add_subdirectory(primary_display)
    add_subdirectory(secondary_display)
elseif(IMX8)
    set(CPACK_COMPONENTS_ALL PRIMARY_DISPLAY SECONDARY_DISPLAY)
    set(CPACK_DEBIAN_PRIMARY_DISPLAY_PACKAGE_ARCHITECTURE "arm64")
    set(CPACK_DEBIAN_SECONDARY_DISPLAY_PACKAGE_ARCHITECTURE "arm64")
    add_subdirectory(primary_display)
    add_subdirectory(secondary_display)
endif()

include(CPack)

secondary_display/CMakeLists.txt示例：

cmake_minimum_required(VERSION 3.0.0)

install(DIRECTORY ${PROJECT_SOURCE_DIR}/apps/secondary_display/resources DESTINATION /opt/unca COMPONENT secondary_display)

install(TARGETS secondary_display DESTINATION /opt/unca COMPONENT secondary_display)
install(TARGETS ahrs DESTINATION /opt/unca COMPONENT secondary_display)
install(TARGETS sns DESTINATION /opt/unca COMPONENT secondary_display)

install(DIRECTORY DESTINATION /var/opt/unca COMPONENT secondary_display
    DIRECTORY_PERMISSIONS
    OWNER_WRITE OWNER_READ OWNER_EXECUTE
    GROUP_WRITE GROUP_READ GROUP_EXECUTE
    WORLD_WRITE WORLD_READ WORLD_EXECUTE
)
install(FILES ${PROJECT_SOURCE_DIR}/resources/configs/net.xml DESTINATION /var/opt/unca COMPONENT secondary_display)

install(FILES services/unca-secondary-display.service DESTINATION /etc/systemd/system/ COMPONENT secondary_display)
install(FILES services/unca-ahrs.service DESTINATION /etc/systemd/system/ COMPONENT secondary_display)
install(FILES services/unca-sns.service DESTINATION /etc/systemd/system/ COMPONENT secondary_display)

set(CPACK_DEBIAN_SECONDARY_DISPLAY_PACKAGE_NAME "unca-secondary-display")
set(CPACK_DEBIAN_SECONDARY_DISPLAY_FILE_NAME "unca-secondary-display-${CPACK_PACKAGE_VERSION}-${CPACK_DEBIAN_DESKTOP_PACKAGE_ARCHITECTURE}.deb")
set(CPACK_DEBIAN_SECONDARY_DISPLAY_DESCRIPTION "UNCA SECONDARY DISPLAY")

string(CONCAT CPACK_DEBIAN_SECONDARY_DISPLAY_PACKAGE_CONTROL_EXTRA
    "${CMAKE_CURRENT_SOURCE_DIR}/debian/prerm;"
    "${CMAKE_CURRENT_SOURCE_DIR}/debian/preinst;"
    "${CMAKE_CURRENT_SOURCE_DIR}/debian/postinst"
)

问题核心是组件名称大小写不匹配：

主CMakeLists.txt中定义的组件是PRIMARY_DISPLAY和SECONDARY_DISPLAY（全大写），但子目录secondary_display/CMakeLists.txt的install指令里指定的组件是secondary_display（全小写）。CPack对组件名称大小写敏感，导致安装内容无法关联到对应的组件包，最终生成空DEB。而设置CPACK_MONOLITHIC_INSTALL 1时，CPack会忽略组件划分，将所有内容打包到主包，因此能正常包含数据。

修复步骤： #

1. 统一组件名称大小写
   选择以下两种方式之一：

   • 将主CMakeLists.txt中的组件名改为小写：

     # IMX6分支修改
     set(CPACK_COMPONENTS_ALL primary_display secondary_display)
     # IMX8分支同理修改
     set(CPACK_COMPONENTS_ALL primary_display secondary_display)
     

   • 或将子目录中所有install指令的COMPONENT参数改为大写：

     install(DIRECTORY ... COMPONENT SECONDARY_DISPLAY)
     install(TARGETS ... COMPONENT SECONDARY_DISPLAY)
     # 所有install指令的COMPONENT都改为大写
     

2. 修正包名架构变量
   secondary_display/CMakeLists.txt中的CPACK_DEBIAN_SECONDARY_DISPLAY_FILE_NAME引用了桌面平台的${CPACK_DEBIAN_DESKTOP_PACKAGE_ARCHITECTURE}，在IMX6/IMX8环境下需替换为对应平台的变量：

   set(CPACK_DEBIAN_SECONDARY_DISPLAY_FILE_NAME "unca-secondary-display-${CPACK_PACKAGE_VERSION}-${CPACK_DEBIAN_SECONDARY_DISPLAY_PACKAGE_ARCHITECTURE}.deb")
   

内容的提问来源于stack exchange，提问作者a.wise