CMake无法确定目标平台的位数

Question

I am trying to cross-compile OpenCV 3.2 for Yocto (i.MX6D).

I create a toolchain.cmake file :

 # compiler
include(CMakeForceCompiler)
cmake_force_c_compiler(arm-poky-linux-gnueabi-gcc GNU)
cmake_force_cxx_compiler(arm-poky-linux-gnueabi-g++ GNU)
# sysroot location
set(MYSYSROOT /opt/poky/1.8/sysroots/cortexa9hf-vfp-neon-poky-linux-gnueabi)
# compiler/linker flags
add_definitions("--sysroot=${MYSYSROOT}")
set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} --sysroot=${MYSYSROOT}" CACHE INTERNAL "" FORCE)
set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} --sysroot=${MYSYSROOT}" CACHE INTERNAL "" FORCE)
# cmake built-in settings to use find_xxx() functions
set(CMAKE_FIND_ROOT_PATH ${MYSYSROOT})
set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)

I run: de@DE:~/OpenCVcross/opencv/build$ cmake -DCMAKE_TOOLCHAIN_FILE=poky-opencv-toolchain.cmake -DOPENCV_EXTRA_MODULES_PATH=/home/de/OpenCVcross/opencv_contrib/modules /home/de/OpenCVcross/opencv

and get this error:

On the internet there are a lot of example to create an image with bitbake includes Opencv 2.4. I don't want to create a new image, just want to compile OpenCV 3.2 with poky.

PS I tried compile a simple hello.c with poky and it was successful.

arm-poky-linux-gnueabi-gcc --sysroot=/opt/poky/1.8/sysroots/cortexa9hf-vfp-neon-poky-linux-gnueabi -mfloat-abi=hard hello.c -o helloworld  

How can I compile OpenCv 3.2 with poky? What is the problem here?

Answer 1

I don't think you need your own toolchain file. Yocto SDK has provided one in /opt/poky/1.8/sysroots/x86_64-pokysdk-linux/usr/share/cmake/OEToolchianConfig.cmake. If you don't specify -DCMAKE_TOOLCHAIN_FILE , this one will be used.