14.2.20. My standalone program does not work

Question:

I tried adding some new code to the hellow_world.c demo program. This works well as soon as I only add code to the existing hello_world() function, but as soon as I add some functions of my own, things go all haywire: the code of the hello_world() function does not get executed correctly, and my new function gets calles with unexpected arguments. What's wrong?

Answer:

You probably failed to notice that any code you add to the example program may shift the entry point address. You should check this using the nm program:

$ ${CROSS_COMPILE}nm -n examples/hello_world
0000000000040004 T testfunc
0000000000040058 T hello_world
000000000004016c t dummy
...

As you can see, the entry point (function hello_world()) is no longer at 0x40004 as it was before, but at 0x40058. Just start your standalone program at this address, and everything should work well.