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Date: Sat, 18 Feb 2006 11:10:00 -0000
From: Randolph Chung <randolph@tausq.org>
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To: Daniel Jacobowitz <drow@false.org>
CC:  msnyder@redhat.com,  gdb@sources.redhat.com
Subject: Re: "run", and executable file/symtab association?
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> If kill_inferior calls pop_target it'd better be expecting to close a
> native target, not the exec target further down the stack.  This looks
> like a bug in the checkpoint code somewhere.  Ugh, the bits in
> kill_inferior are a little scary.  First thing to do: figure out what's
> on the target stack (follow current_target.beneath), and why it's got
> execution if it's popping exec_close.

The target stack looks like:

(top-gdb) print current_target->to_shortname
$2 = 0x334298 "child"
(top-gdb) print current_target->beneath->to_shortname
$3 = 0x334298 "child"
(top-gdb) print current_target->beneath->beneath->to_shortname
$4 = 0x2d7d6c "exec"
(top-gdb) print current_target->beneath->beneath->beneath->to_shortname
$5 = 0x312614 "None"

And to_close is:
(top-gdb) print current_target->to_close
$6 = (void (*)(int)) @0x38465a: 0x47954 <exec_close>

kill_inferior() says:

   /* First cut -- let's crudely do everything inline.  */
   if (forks_exist_p ())
     {
       linux_fork_killall ();
       pop_target ();
       generic_mourn_inferior ();
     }
   else
     {
...
     }

I don't pretend to understand this code and why if there are forks, we 
should be popping the target to kill everything.

Michael Snyder added/changed this when he checked in the checkpoint 
code, perhaps he can comment?

randolph