Unlike solaris, this program demonstrates that glibc has issues resolving
symbols to data elements.  I've tried it with glibc 2.0.7 and 2.1.2, both
with and without x being initialized:

#include <stdio.h>
#include <stdlib.h>

#include <dlfcn.h>

int x=1;

int main()
{
    void *handle = dlopen(NULL, RTLD_NOW);
    int *symbol = (int*)dlsym(handle, "x");
    char *errmsg = dlerror();

    printf("%d\n", x);

    if (symbol)
        printf("%d\n", *symbol);
    else
        printf("error: %s\n", errmsg);
    return 0;
}