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Re: once more into the breach - please try a snapshot so I canrelease this thing

On Fri, 13 Jan 2006, James R. Phillips wrote:

> Although a cygwin package maintainer, I am a complete novice at
> debugging cygwin programs, so please bear with me.
> The current cygwin1.dll snapshot (2006.01.12) causes octave (a package I
> maintain) to dump core under some circumstances.  I haven't been able to
> isolate just what causes it.  When this happens, I get the following
> error message _on_exit_ :
> ===
> octave:3> exit
> Aborted (core dumped)
> ===
> This causes octave to write an octave-core file, which apparently is not
> something gdb understands, but is a binary file that octave can load to
> restart a computation.  I take the core dump error message to have
> originated in octave, rather than cygwin.
> In order to further investigate this, I tried gdb, with the following
> results:
> ===
> $ gdb -q /usr/bin/octave
> (no debugging symbols found)

FWIW, you might want to download the cygwin1.dbg file associated with the
snapshot.  Assuming you save it in /tmp, at this point you'd issue the

(gdb) dll-symbols /tmp/cygwin1.dbg

to load the debugging symbols.  If you've already downloaded the .dbg
file, please ignore this.

> (gdb) run
> Starting program: /usr/bin/octave.exe
> Program received signal SIGSEGV, Segmentation fault.
> 0x610ae8d8 in pthread_key_create () from /usr/bin/cygwin1.dll
> (gdb)
> ===
> I interpret this to mean a segfault has occurred even prior to any
> computations.  This surprises me because if I don't use gdb, I can
> apparently load and exit octave, doing no computations between load and
> exit, without any aborts, segfaults, or obvious error messages.
> Advice on where to go from here in debugging the problem would be
> appreciated.

See <>.
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