new option --readnever & script gstack?

[Daniel Jacobowitz]

On Mon, Nov 29, 2004 at 11:07:06AM -0500, Andrew Cagney wrote:
> Eli Zaretskii wrote:
> >>Cc: gdb@sources.redhat.com
> >>From: "Andrew Burgess" <aab@cichlid.com>
> >>Date: Tue, 23 Nov 2004 13:42:54 -0800
> >>
> >>
> >>>It sounds like the -readnever option you propose would be useful only
> >>>in the pstack-like situation.  So how about adding a -pstack option
> >>>which will do whatever it takes for GDB to emulate pstack, i.e. avoid
> >>>reading the symbols, produce a backtrace, and then detach from the
> >>>process?
> >>
> >>I think I would tend to use it 'with' symbols myself...
> >
> >
> >Then perhaps using the -readnow switch would do what you want.
> >
> >I understand that the motivation for not reading the symbols is the
> >long time it takes GDB to do that, right?
> 
> Yes, the objective is to get in, get a minimal backtrace, and get out. 
> Apparently this is a relatively common task in production environments - 
>  a few seconds down time is considered acceptable but not a few minutes 
> (that's the magnitude difference I'm seeing :-/).  I also don't see the 
> option as being pstack specific - this technique is equally applicable 
> to other scripts - gcore comes to mind - again only minimal symbol 
> information being required.
> 
> So, ..., would a gstack.sh script and an option to disable symbolic 
> debug information reading be useful additions to GDB?

I think so.  I've often wanted a way to load .debug_frame without
loading .debug_info, on platforms with "tricky" unwinding.

The other thing that might be useful is a way to load only shared
libraries which appear in the backtrace (for either .debug_frame or
.debug_info).

-- 
Daniel Jacobowitz