[ELDK] ELDK 5.2 and backtrace on ARM Kirkwood not working

[Andreas Huber]

Hello,

we use glibc's backtrace function to gather some information when our 
software crashes.

(see http://www.kernel.org/doc/man-pages/online/pages/man3/backtrace.3.html)

The program at the bottom of the man page produces the expected result 
for ELDK 4.2. But for ELDK 5.2 it does not work any more:

ELDK 4.2:
$ gcc -rdynamic -o prog prog.c
$ ./prog 3
backtrace() returned 7 addresses
./prog(puts+0x100) [0x8544]
./prog(puts+0x1bc) [0x8600]
./prog(backtrace_symbols+0x248) [0x8644]
./prog(backtrace_symbols+0x240) [0x863c]
./prog(backtrace_symbols+0x240) [0x863c]
./prog(backtrace_symbols+0x2c0) [0x86bc]
/lib/libc.so.6(__libc_start_main+0x1ac) [0x400a2a5c]

ELDK 5.2:
$ gcc -rdynamic -o prog prog.c
$ ./prog 3
backtrace() returned 0 addresses


Trying different compiler flags did not help (-O0, 
-fno-omit-frame-pointer, -g, ...). Maybe I missed the important one for 
this problem.

Has anybody an idea what goes wrong?

Regards,
Andreas

### prog.c from man page
#include <execinfo.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

void
myfunc3(void)
{
     int j, nptrs;
#define SIZE 100
     void *buffer[100];
     char **strings;

     nptrs = backtrace(buffer, SIZE);
     printf("backtrace() returned %d addresses\n", nptrs);

     /* The call backtrace_symbols_fd(buffer, nptrs, STDOUT_FILENO)
        would produce similar output to the following: */

     strings = backtrace_symbols(buffer, nptrs);
     if (strings == NULL) {
         perror("backtrace_symbols");
         exit(EXIT_FAILURE);
     }

     for (j = 0; j < nptrs; j++)
         printf("%s\n", strings[j]);

     free(strings);
}

static void   /* "static" means don't export the symbol... */
myfunc2(void)
{
     myfunc3();
}

void
myfunc(int ncalls)
{
     if (ncalls > 1)
         myfunc(ncalls - 1);
     else
         myfunc2();
}

int
main(int argc, char *argv[])
{
     if (argc != 2) {
         fprintf(stderr, "%s num-calls\n", argv[0]);
         exit(EXIT_FAILURE);
     }

     myfunc(atoi(argv[1]));
     exit(EXIT_SUCCESS);
}