Re: stack unwinding on aix

["Kamal R. Prasad" <kamalpr at yahoo dot com>]

--- Mark Kettenis <mark.kettenis@xs4all.nl> wrote:

>    Date: Mon, 20 Jun 2005 23:25:50 -0700 (PDT)
>    From: "Kamal R. Prasad" <kamalpr@yahoo.com>
> 
>    Hello,
> 
>     I am trying to locate a piece of code in gdb 6.3
>    which does srack unwinding in AIX (5.3). When
>    unwinding the stack in my C code, I noticed a lot
> of
>    dummy frames whose pc points to the data segment
>    and/or outside th text segment(s). Can someone
> tell me
>    how gdb identifies such dummy frames and wherein
> the
>    code base it is? rs6000-tdep.c contains some algo
> for
>    frameless function detection etc.., but that
> isn't all
>    to it.
> 
> I'm afraid the AIX/RS6000/POWER code is suffering
> from quite a bit of
> bit-rot.  It's a bit of a mess, so I can't blame you
> for failing to
> understand the code.  The sparc, vax or m88k code
> might be much easier
> for you to understand..  Look frame functions name
> xxx_frame_cache,
> xxx_prev_register for code that does the stack
> unwinding.
> 
Doing the stack unwinding is the easier part. The
difficult part is identifying intermediate aka dummy
frames.I believe some dummyframes get introduced due
to late binding.
> Anyway, the AIX/RS6000/POWER support in gdb really
> could use some
> loving care.  AFAIK almost none of the gdb
> developers actually have
> access to an AIX system.  So I'm not sure we'll be
> able to help you.
> 
gdb actually works fine on AIX -and Im looking to
import existing functionality from gdb to my s/w, not
re-work gdb which you seem to be implying. I have a
set of AIX systems at the workplace, but Im not sure
if I can give outsiders access for security reasons.
Is  skip_prologue() the core of functionality that
identifies what to do with a frame?

regards
-kamal

> Mark
> 


------------------------------------------------------------
Kamal R. Prasad
UNIX systems consultant 
http://members.fortunecity.com/kamalp
kamalp@acm.org

In theory, there is no difference between theory and practice. In practice, there is.
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