Thread backtrace termination
Jonathan Larmour
jifl@eCosCentric.com
Tue Jul 12 18:32:00 GMT 2005
Daniel Jacobowitz wrote:
> 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.
[snip]
> The error is caught in the top level code for the backtrace command;
> that effectively downgrades it to a warning and backtrace termination.
Ah ok, thanks.
>>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.
It's possibly alarmist, but it's no big deal.
> Well, the patch was:[snip]
> You can find the discussion and sample use on gdb@ a month or two
> earlier.
Aha, yes, at
http://sources.redhat.com/ml/gdb-patches/2005-03/msg00047.html and friends.
That seems interesting but somewhat unwieldy, and as you said before,
wouldn't apply to compiler generated code.
>>>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.
If someone were to come up with an __attribute__ that could be used with
GCC to mark functions to be annotated this way, it might be possible. But
it's beyond me (or at least, beyond what I have time to get up to speed
with) and I doubt anyone else will be that interested. Ho hum.
>>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.
Well, I'm prepared to create a patch to add such a command if people here
think something with that principle would be accepted.
Jifl
--
eCosCentric http://www.eCosCentric.com/ The eCos and RedBoot experts
--["No sense being pessimistic, it wouldn't work anyway"]-- Opinions==mine
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