I am trying to build applications for my Raspberry Pi using a cross compiler by using crosstool-ng. My build system is Ubuntu 14.04 LTS.
When I tried building a test program, it works.
On build system:
$ cat > prog_without_so.cpp
#include <iostream>
int main() { std::cout << "Hello, world!\n"; return 0; }
^D
$ arm-unknown-linux-gnueabi-gcc -std=c++0x -lstdc++ -o prog_without_so prog_without_so.cpp
On Pi:
$ ./prog_without_so
Hello, world!
However, when I tried to run a program that uses shared libraries, it returns this:
On Pi:
$ LD_LIBRARY_PATH="." ./prog_with_so
./prog_with_so: error while loading shared libraries: librsmath.so: cannot open shared object file: No such file or directory
Curious, I tried ldd and file:
On Pi:
$ ldd prog_with_so
not a dynamic executable
$ file ./prog_with_so
./prog_with_so: ELF 32-bit LSB executable, ARM, EABI5 version 1 (SYSV), dynamically linked, interpreter /lib/ld-linux.so.3, for GNU/Linux 4.3.0, not stripped
Also tried the same on the first program:
$ ldd prog_without_so
not a dynamic executable
$ file ./prog_without_so
./prog_without_so: ELF 32-bit LSB executable, ARM, EABI5 version 1 (SYSV), dynamically linked, interpreter /lib/ld-linux.so.3, for GNU/Linux 4.3.0, not stripped
I wasn't able to find anything new here.
What's going on? Is my cross-compiler incorrectly set up? Why does it fail only when the application depends on a shared library?
This is my source for the second program:
//somemath.h
#include <iostream>
class CSum {
int _sum;
public:
CSum(int i):_sum(i) {}
CSum operator+=(int i);
friend std::ostream& operator<<( std::ostream& out, const CSum& sum); // output;
};
//somemath.cpp
#include "somemath.h"
CSum CSum::operator+=(int i)
{
_sum += i;
}
std::ostream& operator<<( std::ostream& out, const CSum& sum) // output
{
out << "(" << sum._sum << ")";
return out;
}
//test.cpp
#include <iostream>
#include <cstdlib>
#include "somemath.h"
CSum sum(1);
int main(int argc, char* argv[])
{
if (argc>1)
{
int n = 1;
while(n<argc)
{
sum+=atoi(argv[n]);
std::cout<< sum << " ";
++n;
}
std::cout << "\n";
}
else
{
std::cout <<"Usage: " << argv[0] << " [2 3 4 ... ]\n";
}
return 0;
}
Here's how I compile and link them on my build system:
arm-unknown-linux-gnueabi-gcc -shared somemath.cpp -std=c++0x -fPIC -lstdc++ -o librsmath.so
arm-unknown-linux-gnueabi-gcc test.cpp -o prog_with_so -std=c++0x -L ./ -lstdc++ -lrsmath
