On 6/18/2013 11:53 AM, Eli Zaretskii wrote:
> As for displaying the backtrace, just add the "bt" command to the
> chain, like this:
>
>    emacsdbg = EMACSLOADPATH=$(lisp) LC_ALL=C gdb --batch --return-child-result -ex 'b abort' -ex run -ex bt -ex cont --args $(EMACS) $(EMACSOPT)
>
> GDB executes the commands given via -ex in order, so think of this as
> if you typed the commands whenever GDB shows its prompt.

Thanks, Eli.  I replaced "bt" by "thread apply all bt", which probably 
didn't provide additional useful information.  I then ran "make 
bootstrap" followed by repeated "make -k" until the bootstrap completed. 
  Early in the process there were two crashes with SIGSEGV, for which I 
got backtraces (attached).  In both cases the crash occurred in 
gmalloc.c, which probably explains why we're seeing problems only on Cygwin.

After that there were many compile failures with errors like those that 
others have reported:

Compiling gnus/gnus-cache.el
GLib (gthread-posix.c): Unexpected error from C library during 
'pthread_setspecific': Invalid argument.  Aborting.
Makefile:254: recipe for target `gnus/gnus-cache.elc' failed

But these compilations didn't invoke gdb, apparently because they 
involved Makefile targets other than compile-onefile.  So I didn't get 
any more backtraces.

I can modify the Makefile further if necessary, but the attached 
backtraces are a start.

Ken