Fwd: Re: Strange gdb backtraces on 64-bit Cygwin

[Ken Brown]

On 9/23/2014 9:23 AM, Markus Hoenicka wrote:
> At 2014-09-23 14:31, Ken Brown was heard to say:
>>
>> So I think it's pretty clear that the strange backtrace I observed
>> with gdb-7.6.50-4 on 64-bit Cygwin was indeed due to a deficiency in
>> gdb.
>>
>> I hope that people who have been experiencing emacs crashes with
>> "impossible" backtraces will update to gdb-7.8-2.
>>
>
> Hi,
>
> I might be dense somehow, but the two emacs crashes with said
> "impossible" backtraces that I reported yesterday [1][2] were observed
> with the gdb version that you recommend:
>
> $ gdb -version
> GNU gdb (GDB) 7.8
> [...]
>
> $ cygcheck -f /usr/bin/gdb
> gdb-7.8-2
>
> Are you sure this is all it takes to get sane backtraces?

The "impossible" backtraces that you were getting earlier were the ones 
that showed run_timers in Thread 2.  This problem didn't occur with the 
backtraces that you reported yesterday.  The only problem with those 
backtraces was the lack of detail in Thread 1.  Eli suggested one 
possible explanation.  Another is that the stack had gotten messed up by 
whatever caused the crash, so that gdb was unable to unwind it.  If we 
ever get any clue as to what's causing these crashes, we might come up 
with a reasonable place to set a breakpoint in order to get a useful 
backtrace.

By the way, I'm sure that one or more of your threads are created by 
Glib.  So installing the debuginfo for Glib as I suggested yesterday 
might help, at least in those cases where the crash/abort involves Glib.

Ken

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