Re: The generated binary code has different main?

From: Mike Frantzen (frantzen@w4g.org)
Date: 09/05/02 

Date: Thu, 5 Sep 2002 00:06:45 -0400
From: Mike Frantzen <frantzen@w4g.org>
To: Minchu Mo <morris_minchu@iwon.com>

> I used cc compiler to compile a simple c code under solaris /sparc. The c
> code has main(int argc, char* argv[]) function as entry point as everybody
> knows.
> But when I run the generated code under adb, I found the main function
> under adb look like this:
> main(2,ffbefd0c,ffbefd18,20800,0,0)
> I know that:
> 2 is the number of arguments,
> ffbefd0c is *argv
> ffbefd18 is *envp,
> but what are 20800 and 0, 0 for?
> Anybody knows? Thanks

Sparc uses register windows. There are eight input registers %i0
through %i7. But %i6 is the frame pointer (actually the previous
functions stack pointer. And %i7 is used as the return pointer (which
was the previous functions program counter aka instruction pointer).

Thus the first six parameters are always passed in registers and the
debugger doesn't really have an easy way to determine how many were
actually passed or will actually be used.

The 20800 is probabley left over from a constructor, _init or the dl
hocus pocus.

.mike
frantzen@(nfr.com | cvs.openbsd.org | w4g.org)

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