[Pgubook-readers] toupper and command line args

[Aaron Miller]

I'm really getting a lot out of this book.

I'm having some difficulty reconciling the explanation of how Linux passes in 
command line params at the bottom of page 91 with the way the toupper example 
actually works.

At the bottom of page 91, he explains that when a program begins, the number 
of args is at 8(%esp), the name of the program at 12(%esp), and that the 
arguments start at 16(%esp). 

Well, when a program begins, aren't the stack pointer and the base pointer the 
same? If this is the case, then why in toupper does he retrieve the first 
argument from 8(%ebp)? 

Running it through gdb, if I break it right after the first instruction in 
_start, argc is at %esp (same as %ebp at this point), argv[0] is at 4(%esp), 
arg[1] at 8(%esp) and so on...

But I keep thinking I'm missing something, because page 91 makes it clear that 
the first arg should be at 16(%esp), not 8(%esp).

I'm probably being dense here, but could someone clarify this for me?

Thanks,
Aaron