how to cross compile opencv on nvidia xaiver arm platform

Guide

systems:

ubuntu 16.04
gnu gcc/g++ 5.4.0
cmake
cmake-gui
opencv 3.1.0

arm toolchain for cross-compiling

arm-linux-gnueabi-gcc 5.4.0
arm-linux-gnueabi-g++ 5.4.0

check

which arm-linux-gnueabi-gcc
/usr/bin/arm-linux-gnueabi-gcc

which arm-linux-gnueabi-g++
/usr/bin/arm-linux-gnueabi-g++

which gcc
/usr/bin/gcc

which g++
/usr/bin/g++

compiling

Difference between Native and Cross compiler

A native compiler is one that compiles programs for the same architecture or operating system that it is running on. For instance, a compiler running on an x86 processor and creating x86 binaries.
A cross-compiler is one that compiles binaries for architectures other than its own, such as compiling ARM binaries on a Intel’s x86 processor.A “cross compiler” executes in one environment and generates code for another. A “native compiler” generates code for its own execution environment.

2 types:

native compiling: compile on x86 for x86 binaries, run on x86
cross compiliing: compile on x86 for arm binaries, run on arm

install gnu tools

1	sudo apt-get install gcc g++

install arm toolchain

apt-get

Toolchains have a loose name convention like [arch] – [vendor] – [os] – [abi]

arch is for architecture: arm, mips, x86, i686…
vendor is tool chain supplier: apple,
os is for operating system: linux, none (bare metal)
abi is for application binary interface convention: eabi, gnueabi, gnueabihf

install toolchains

1	sudo apt-get install gcc-arm-linux-gnueabi g++-arm-linux-gnueabi

install 32-bit libraries

1	sudo apt-get install lib32ncurses5 lib32z1

compile like gnu gcc/g++

1 2	arm-linux-gnueabi-gcc -o hello hello.c arm-linux-gnueabi-g++ -o hello hello.c

hello only run on arm

source

arm-linux-gnueabi-4.5.1.tar.bz2

cmake

1 2	cd opencv-3.1.0 mkdir build && cd build && cmake-gui ..

config
page 1

Unix Makefiles
Specify options for cross-compiling

page 2

operating system: arm-linux
c compiler: /usr/bin/arm-linux-gnueabi-gcc
c++ compiler:/usr/bin/arm-linux-gnueabi-g++
Target ROot: /usr/bin

common cmake options:

CMAKE_INSTALL_PREFIX /usr/local/arm/opencv-arm

Generate and Configure.

make -j8

view file

x86-64

file /usr/local/lib/libgtest.so     
/usr/local/lib/libgtest.so: ELF 64-bit LSB shared object, x86-64, version 1 (GNU/Linux), dynamically linked, BuildID[sha1]=3d9e1f42d0584435a3e6aadb11eabfe620a8d52a, not stripped

arm

file libopencv_core.so 
libopencv_core.so: ELF 32-bit LSB shared object, ARM, EABI5 version 1 (GNU/Linux), dynamically linked, BuildID[sha1]=ce2523820bc6a80972c49e465436d8220abf632c, not stripped

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