I've been trying to cross compile opencv for an ARM target system. My project is dependent to use opencv 2.4.11.
The target system is a petalinux 2017.2 running on a quad-core Cortex A53 of a Zynq Ultrascale+ FPGA.
My host system is an Ubuntu 16.04 x86_64.
I used the following toolchain.cmake file for configuration:
set( CMAKE_SYSTEM_NAME Linux)
set( CMAKE_SYSTEM_PROCESSOR arm)
set( CMAKE_C_COMPILER /home/benjaminh/petalinux_2017_2/tools/linux-i386/aarch64-linux-gnu/bin/aarch64-linux-gnu-gcc)
set( CMAKE_CXX_COMPILER /home/benjaminh/petalinux_2017_2/tools/linux-i386/aarch64-linux-gnu/bin/aarch64-linux-gnu-g++)
set( CMAKE_FIND_ROOT_PATH /home/benjaminh/embedded_development/ultrazed_repo/scripts/rootfs_part)
SET(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
SET(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
I performed the following steps:
wget https://github.com/Itseez/opencv/archive/2.4.11.zip
unzip 2.4.11.zip
cd opencv-2.4.11
mkdir build
cd build
cmake -DCMAKE_TOOLCHAIN_FILE=toolchain.cmake ../
make -j4
As you can see, the build process failed with: error: unknown register name 'st' in 'asm'. It seems that it attemps to interpret a x86_64 library with an ARM compiler
[ 44%] Building CXX object modules/video/CMakeFiles/opencv_video.dir/src/bgfg_gaussmix.cpp.o
[ 44%] Building CXX object modules/photo/CMakeFiles/opencv_photo.dir/src/denoising.cpp.o
In file included from /home/benjaminh/petalinux_2017_2/tools/linux-i386/aarch64-linux-gnu/aarch64-linux-gnu/libc/usr/include/math.h:472:0,
from /home/benjaminh/petalinux_2017_2/tools/linux-i386/aarch64-linux-gnu/aarch64-linux-gnu/include/c++/6.2.1/cmath:45,
from /home/benjaminh/petalinux_2017_2/tools/linux-i386/aarch64-linux-gnu/aarch64-linux-gnu/include/c++/6.2.1/math.h:36,
from /home/benjaminh/embedded_development/opencv-2.4.11/modules/core/include/opencv2/core/types_c.h:94,
from /home/benjaminh/embedded_development/opencv-2.4.11/modules/core/include/opencv2/core/core.hpp:49,
from /home/benjaminh/embedded_development/opencv-2.4.11/modules/highgui/include/opencv2/highgui/highgui.hpp:46,
from /home/benjaminh/embedded_development/opencv-2.4.11/modules/highgui/src/precomp.hpp:47,
from /home/benjaminh/embedded_development/opencv-2.4.11/modules/highgui/src/cap_images.cpp:52:
/usr/include/x86_64-linux-gnu/bits/mathinline.h: In member function ‘virtual bool CvCapture_Images::setProperty(int, double)’:
/usr/include/x86_64-linux-gnu/bits/mathinline.h:889:3: error: unknown register name ‘st’ in ‘asm’
__lrint_code;
^
/usr/include/x86_64-linux-gnu/bits/mathinline.h:889:3: error: unknown register name ‘st’ in ‘asm’
__lrint_code;
^
modules/highgui/CMakeFiles/opencv_highgui.dir/build.make:86: recipe for target 'modules/highgui/CMakeFiles/opencv_highgui.dir/src/cap_images.cpp.o' failed
make[2]: *** [modules/highgui/CMakeFiles/opencv_highgui.dir/src/cap_images.cpp.o] Error 1
CMakeFiles/Makefile2:2275: recipe for target 'modules/highgui/CMakeFiles/opencv_highgui.dir/all' failed
make[1]: *** [modules/highgui/CMakeFiles/opencv_highgui.dir/all] Error 2
make[1]: *** Waiting for unfinished jobs....
[ 44%] Building CXX object modules/video/CMakeFiles/opencv_video.dir/src/lkpyramid.cpp.o
[ 44%] Building CXX object modules/video/CMakeFiles/opencv_video.dir/src/video_init.cpp.o
[ 44%] Building CXX object modules/video/CMakeFiles/opencv_video.dir/src/bgfg_gmg.cpp.o
[ 44%] Building CXX object modules/video/CMakeFiles/opencv_video.dir/src/tvl1flow.cpp.o
[ 44%] Building CXX object modules/video/CMakeFiles/opencv_video.dir/src/bgfg_gaussmix2.cpp.o
[ 44%] Linking CXX shared library ../../lib/libopencv_photo.so
[ 44%] Built target opencv_photo
[ 44%] Building CXX object modules/video/CMakeFiles/opencv_video.dir/src/kalman.cpp.o
[ 44%] Building CXX object modules/video/CMakeFiles/opencv_video.dir/src/simpleflow.cpp.o
[ 44%] Linking CXX shared library ../../lib/libopencv_video.so
[ 44%] Built target opencv_video
Makefile:160
: recipe for target 'all' failed
make: *** [all] Error 2
From time to time during the build process warnings like these occure, which indicates that there is something wrong with the set path:
cc1plus: warning: include location "/usr/include/glib-2.0" is unsafe for cross-compilation [-Wpoison-system-directories]
cc1plus: warning: include location "/usr/include/freetype2" is unsafe for cross-compilation [-Wpoison-system-directories]
cc1plus: warning: include location "/usr/include/x86_64-linux-gnu" is unsafe for cross-compilation [-Wpoison-system-directories]
For me it is not clear why it is taking the host path and not the given target root path.
Your toolchain file is incomplete. Does petalinux provide one?
You need to add directives so that make will not attempt to use host includes when building target objects:
set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY)
You may also need to specify the target sys root:
set(CMAKE_SYSROOT /home/devel/petalinux-rootfs)