Basically, I have this C function linked:
```c
/*
 * Copyright (C) 2004 CodeSourcery, LLC
 *
 * Permission to use, copy, modify, and distribute this file
 * for any purpose is hereby granted without fee, provided that
 * the above copyright notice and this notice appears in all
 * copies.
 *
 * This file is distributed WITHOUT ANY WARRANTY; without even the implied
 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 */

/* Handle ELF .{pre_init,init,fini}_array sections.  */
#include <sys/types.h>

/* These magic symbols are provided by the linker.  */
extern void (*__preinit_array_start[])(void) __attribute__((weak));
extern void (*__preinit_array_end[])(void) __attribute__((weak));
extern void (*__init_array_start[])(void) __attribute__((weak));
extern void (*__init_array_end[])(void) __attribute__((weak));

extern void _init(void);

/* Iterate over all the init routines.  */
__attribute__((__used__)) void __libc_init_array(void)
{
    size_t count;
    size_t i;

    count = __preinit_array_end - __preinit_array_start;
    for (i = 0; i < count; i++)
        __preinit_array_start[i]();

    _init();

    count = __init_array_end - __init_array_start;
    for (i = 0; i < count; i++)
        __init_array_start[i]();
}

/* Dummy function to throw a linker error if defined elsewhere. */
void _init(void)
{
}
```