printfs inside a shared object (dynamic library) not getting printed

Question

Hello,

I have a shared object which i create on windows using Real View developer suite tool linked command on windows host-

armlink -o mylib.so <"my *.o files given here">

Then i link an application with this mylib.so shared library on linux using gcc tools.

I have printf statements inside functions in this mylib.so, but when I run the final executable, i do not get any printf outputs on console.(stdio.h is inlcuded wherever printfs are called)

So is there any known issue with shared libraries which cause printf or any system functions/system calls/run time library functions not to work correctly?

Or is that got to do with my peculiar setup of making a shared library on windows based compiler tool chain but linking this shared library with an application on linux-gcc compiler tools?

Thank you.

-AD

Answer 1

Since your target is arm, and I assume this is C it should not be a problem to compile some files on windows and then link on linux. Have you verified this however? I would suggest making a hello.so on windows, linked from hello.c:

#include <stdio.h>
void hello(void) {printf("Hello\n");}

and then link main from main.c on linux:

void hello(void);
int main(int argc, char *argv[]){ hello(); return 0; }

as a minimum compiler chain test.

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If you call printf from code in defined in your final executable (i.e. not code from your shared library) do you get any output from that?

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Does

strings --print-file-name -a mylib.so final_executable | grep "string from printf in shared library"

return two occurenses?

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Are there any references to printf in

readelf -a mylib.so
readelf -a final_executable

?