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Re: Thread backtrace termination
On Mon, Jul 11, 2005 at 06:52:13PM +0100, Jonathan Larmour wrote:
> Daniel Jacobowitz wrote:
> >On Mon, Jul 11, 2005 at 05:20:55PM +0100, Jonathan Larmour wrote:
> >
> >>The two "global constructors keyed to cyg_scheduler_start" lines are
> >>bogus frame entries, although those also happened with GDB 6.1. The
> >>"corrupt stack" whinge is new, and is treated as an error, including
> >>terminating gdbinit scripts etc.
> >
> >
> >This is already changed in CVS.
>
> Okay. I haven't seen that. It still looks like an error to me in frame.c.
The error is caught in the top level code for the backtrace command;
that effectively downgrades it to a warning and backtrace termination.
> BTW, my other web searches seem to indicate that a fair few (naive) people
> are thinking they are having stack corruption because GDB thinks there
> might be. That's unfortunate.
What else would you suggest? GDB is confused. From its point of view,
the stack _is_ corrupt.
> I've had a search for this and not found anything. I'm probably just not
> using the right terms. Do you have a pointer, time frame or some search
> terms I can use to pin this down? Thanks.
Well, the patch was:
2005-04-08 Daniel Jacobowitz <dan@codesourcery.com>
* dwarf2-frame.c (struct dwarf2_frame_cache): New field
undefined_retaddr.
(dwarf2_frame_cache): Initialize undefined_retaddr.
(dwarf2_frame_this_id): Return an invalid frame ID if
undefined_retaddr.
You can find the discussion and sample use on gdb@ a month or two
earlier.
> >For compiler-generated code there's really no useful way to do this.
>
> I guess atleast now I know that, which saves me spending more time.
>
> Wouldn't it make sense to make such a convention though, such as having a
> return address of 0?
This is basically a convention. You could, I suppose, patch a compiler
to generate it. I'm not sure that would be wise.
> Alternatively, how about adding a new command that allows you to define a
> set of entry point symbol names? People can then put an appropriate list
> for themselves or their OS in ~/.gdbinit. Or it can be pre-initialised by
> the OS support within GDB if there is one. e.g. nm-linux.h. Here's what
> I'm thinking of:
>
> set entry-point-name-list main _start _entry
>
> Although handling mangled symbols and multiple languages might be fun. I'm
> not an expert on such things.
*shrug* maybe.
--
Daniel Jacobowitz
CodeSourcery, LLC