Re: IA32: printing FP register variables

[Jim Blandy <jimb@cygnus.com>]

> On Mon, Jul 19, 1999 at 03:26:18PM -0500, Jim Blandy wrote:
> > Once the other internal work is done, would the EGCS folks be willing
> > to experiment with both, and give us some sense of how much difference
> > it makes?
> 
> Yes.  It seems a reasonable thing to try.

Okay.  So the current plan is:

1) EGCS folks get regstack to actually propagate the variable/register
   mapping to its output accurately.
2) EGCS folks make sure accurate LRS information is generated.
3) EGCS folks compare output size using base-relative and top-relative
   numberings.  Unless the space savings are persuasive, we stick with
   the more intuitive and more widely used top-relative numbering.
4) Once EGCS is generating the information correctly, GDB folks implement
   support for whatever numbering system the EGCS folks recommend.
From jimb@cygnus.com Mon Jul 26 11:55:00 1999
From: Jim Blandy <jimb@cygnus.com>
To: Neal Cardwell <cardwell@cs.washington.edu>
Cc: gdb@sourceware.cygnus.com
Subject: Re: signals at breakpoints in Linux
Date: Mon, 26 Jul 1999 11:55:00 -0000
Message-id: <npbtcz44xd.fsf@zwingli.cygnus.com>
References: <Pine.LNX.4.10.9907240149141.3002-100000@saba.cs.washington.edu>
X-SW-Source: 1999-q3/msg00099.html
Content-length: 979

> I'm trying to build a minimal debugger under Linux that maintains a set of
> breakpoints and prints out some information each time a breakpoint is hit.
> It works fine, except for the case where the child process executes a
> breakpoint instruction and wait(2) tells me that a (non-SIGTRAP) signal is
> pending. I can't seem to handle this case correctly, no matter what i try.
> What is the correct course of action when a breakpoint and signal are
> encountered simultaneously? I've tried looking at the sources for GDB, but
> they're pretty tough to wade through.

I'm not positive about this, but I think you're misunderstanding the
results from ptrace.  Not that they're wonderfully clear to begin
with.

The result from wait tells you why the program stopped.  As I
understand it, it either stopped because of a breakpoint, or it
stopped because of a signal --- it can't stop for both reasons.

What exactly is wait returning?  Where exactly is the PC when wait
returns?
From rogerc@ignitus.com Mon Jul 26 13:01:00 1999
From: Roger Cruz <rogerc@ignitus.com>
To: gdb@sourceware.cygnus.com
Subject: How do I type cast an array of strings in GDB?
Date: Mon, 26 Jul 1999 13:01:00 -0000
Message-id: <379CBFBC.6164B1CA@ignitus.com>
X-SW-Source: 1999-q3/msg00100.html
Content-length: 1158

I have the following definition in a file, compiled without the -g switch:

LOCAL char *  semTypeMsg [MAX_SEM_TYPE] =
    {
    "BINARY", "MUTEX", "COUNTING", "OLD", "\0", "\0", "\0", "\0"
    };

I want to index this array to get to the different strings:

(gdb) p semTypeMsg[0]
cannot subscript something of type `<data variable, no debug info>'
(gdb) whatis semTypeMsg
type = <data variable, no debug info>

But because it was compiled without the -g switch, I can't do this
directly.  How do I cast this variable name to allow me access to the
strings?  I've tried a bunch of compinations and they are all unsuccessful

(gdb) p ((char *)semTypeMsg)
$19 = 0xfdd8c "BINARY"
(gdb) p ((char *)semTypeMsg)[0]
$20 = 66 'B'
(gdb) p ((char **)semTypeMsg)[0]
$21 = 0x42494e41Requested target address (0x42494e41) is outside
the valid memory range: 0x0-0x1000000

(gdb) p ((char **)semTypeMsg)+1
$22 = (char **) 0xfdd90
(gdb) p *(((char **)semTypeMsg)+1)
$23 = 0x52590000Requested target address (0x52590000) is outside
the valid memory range: 0x0-0x1000000

(gdb) p (char *)(((char **)semTypeMsg)+1)
$24 = 0xfdd90 "RY"
(gdb) p (char *)(((char **)semTypeMsg)+1)