Cross compiling error: "Could NOT find PahoMqttC (missing: PAHO_MQTT_C_LIBRARIES PAHO_MQTT_C_INCLUDE_DIRS)"

[locnnil]

I'm trying to cross compile the mqtt C++ lib to use in my embedded linux device ( An armv7l device), then I add as a submodule paho.mqtt.cpp and also paho.mqtt.c and inside my project I created a lib folder to be installed all my dependencies. Basicaly, I ran:

In my project root folder:

$ mkdir lib 
$ cd lib
$ git submodule add [email protected]:eclipse/paho.mqtt.cpp.git
$ git submodule add [email protected]:eclipse/paho.mqtt.c.git
$ mkdir -p mqtt/paho.mqtt.cpp
$ mkdir -p mqtt/paho.mqtt.c

Then I configure, compile and install sucefully paho.mqtt.c inside mqtt/paho.mqtt.c running:

$ cd paho.mqtt.c
$ git checkout v1.3.8
$ cmake -Bbuild -H. \
    -DPAHO_ENABLE_TESTING=OFF \
    -DPAHO_BUILD_STATIC=ON \
    -DPAHO_WITH_SSL=OFF \
    -DPAHO_HIGH_PERFORMANCE=ON \
    -DCMAKE_INSTALL_PREFIX=$HOME/fibocom/openlinux/marthe_linux/lib/mqtt/paho_c \
    -DCMAKE_TOOLCHAIN_FILE=$HOME/toolchain-arm-linux-gnueabi.cmake

$ sudo cmake --build build/ --target install

The toolchain-arm-linux-gnueabi.cmake file that I'm using is this file

Then, looks like it configure, compiles and installed successfully.

The configuration:

Compilation and installation:

The installed folders:

Then in the paho.mqtt.cpp lib installation:

$ cd ~/My_project_root/lib/paho.mqtt.cpp
$ git checkout master
$ cmake -Bbuild -H. \
    -DPAHO_BUILD_SHARED=FALSE \
    -DPAHO_WITH_SSL=FALSE \
    -DPAHO_BUILD_DOCUMENTATION=OFF \
    -DPAHO_BUILD_SAMPLES=ON \
    -DPAHO_BUILD_STATIC=ON \
    -DCMAKE_PREFIX_PATH=$HOME/fibocom/openlinux/marthe_linux/lib/mqtt/paho_c \
    -DCMAKE_INSTALL_PREFIX=$HOME/fibocom/openlinux/marthe_linux/lib/mqtt/paho_cpp \
    -DCMAKE_TOOLCHAIN_FILE=$HOME/toolchain-arm-linux-gnueabi.cmake

I got the followed output:

-- The CXX compiler identification is GNU 9.4.0
-- Check for working CXX compiler: /usr/bin/arm-linux-gnueabi-g++
-- Check for working CXX compiler: /usr/bin/arm-linux-gnueabi-g++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
CMake Error at /usr/share/cmake-3.16/Modules/FindPackageHandleStandardArgs.cmake:146 (message):
  Could NOT find PahoMqttC (missing: PAHO_MQTT_C_LIBRARIES
  PAHO_MQTT_C_INCLUDE_DIRS)
Call Stack (most recent call first):
  /usr/share/cmake-3.16/Modules/FindPackageHandleStandardArgs.cmake:393 (_FPHSA_FAILURE_MESSAGE)
  cmake/FindPahoMqttC.cmake:33 (FIND_PACKAGE_HANDLE_STANDARD_ARGS)
  src/CMakeLists.txt:26 (find_package)


-- Configuring incomplete, errors occurred!
See also "/home/lincoln/fibocom/openlinux/marthe_linux/lib/paho.mqtt.cpp/build/CMakeFiles/CMakeOutput.log".

My output log:
CMakeOutput.log

I don't understand why this is getting an error, the path to paho C already has
been specified

Information about my system:

Linux 5.10.102.1-microsoft-standard-WSL2 #1 SMP Wed Mar 2 00:30:59 UTC 2022 x86_64 x86_64 x86_64 GNU/Linux

[rafalSFara]

I had similar problem and I was able to solve it by setting:

'CMAKE_FIND_ROOT_PATH_MODE_LIBRARY' = 'BOTH'
'CMAKE_FIND_ROOT_PATH_MODE_INCLUDE' = 'BOTH'

[locnnil]

Interesting @rafalSFara did you set this using the command options when running cmake? Like:

cmake -Bbuild -H. \
    -DPAHO_BUILD_SHARED=FALSE \
    -DPAHO_WITH_SSL=FALSE \
    -DPAHO_BUILD_DOCUMENTATION=OFF \
    -DPAHO_BUILD_SAMPLES=ON \
    -DPAHO_BUILD_STATIC=ON \
    -DCMAKE_PREFIX_PATH=$HOME/fibocom/openlinux/marthe_linux/lib/mqtt/PahoMqttC \
    -DCMAKE_INSTALL_PREFIX=$HOME/fibocom/openlinux/marthe_linux/lib/mqtt/PahoMqttCPP \
    -DCMAKE_TOOLCHAIN_FILE=$HOME/toolchain-arm-linux-gnueabi.cmake \
    -DCMAKE_FIND_ROOT_PATH_MODE_LIBRARY=BOTH \
    -DCMAKE_FIND_ROOT_PATH_MODE_INCLUDE=BOTH

I've try this way but still not working.

[rafalSFara]

Actually I've used it in the conan recipe, but your usage looks correct to me.
Maybe you should try with explicitly set CMAKE_FIND_ROOT_PATH to PahoMqttC then?

[locnnil]

I'm trying to isolate my problem, so now I'm tryng to install both in a separed folder, but still not working. I can install paho.mqtt.c but when I try to install the C++ library It fails on Cmake configuration.

Following your tip, I tried:

cmake -Bbuild -H. \
    -DPAHO_BUILD_SHARED=FALSE \
    -DPAHO_WITH_SSL=FALSE \
    -DPAHO_BUILD_DOCUMENTATION=OFF \
    -DPAHO_BUILD_SAMPLES=ON \
    -DPAHO_BUILD_STATIC=ON \
    -DCMAKE_TOOLCHAIN_FILE=$HOME/toolchain-arm-linux-gnueabi.cmake \
    -DCMAKE_PREFIX_PATH=$HOME/projects/mqtt/lib \
    -DCMAKE_INSTALL_PREFIX=$HOME/projects/mqtt/lib \
    -DCMAKE_FIND_ROOT_PATH=$HOME/projects/mqtt/lib \
    -DCMAKE_FIND_ROOT_PATH_MODE_LIBRARY=BOTH \
    -DCMAKE_FIND_ROOT_PATH_MODE_INCLUDE=BOTH

But it still getting the same error.

[dovantuan02]

I'm trying to isolate my problem, so now I'm tryng to install both in a separed folder, but still not working. I can install paho.mqtt.c but when I try to install the C++ library It fails on Cmake configuration.

Following your tip, I tried:

cmake -Bbuild -H. \
    -DPAHO_BUILD_SHARED=FALSE \
    -DPAHO_WITH_SSL=FALSE \
    -DPAHO_BUILD_DOCUMENTATION=OFF \
    -DPAHO_BUILD_SAMPLES=ON \
    -DPAHO_BUILD_STATIC=ON \
    -DCMAKE_TOOLCHAIN_FILE=$HOME/toolchain-arm-linux-gnueabi.cmake \
    -DCMAKE_PREFIX_PATH=$HOME/projects/mqtt/lib \
    -DCMAKE_INSTALL_PREFIX=$HOME/projects/mqtt/lib \
    -DCMAKE_FIND_ROOT_PATH=$HOME/projects/mqtt/lib \
    -DCMAKE_FIND_ROOT_PATH_MODE_LIBRARY=BOTH \
    -DCMAKE_FIND_ROOT_PATH_MODE_INCLUDE=BOTH

But it still getting the same error.

hello guy. I have same problem. How do you fix it ?

[fpagliughi]

@dovantuan02 Post the toolchain file that you're using and I will try to recreate the problem.
(toolchain-arm-linux-gnueabi.cmake)