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Date: Thu, 23 Oct 2008 15:54:51 +0200
From: Corinna Vinschen <corinna-cygwin AT cygwin DOT com>
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Subject: Re: cygwin bash crashes on Win Serv 2008
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On Oct 20 14:42, Freddy Jensen wrote:
> 
> Apparently the cygwin bash crash on Win Serv 2008 is related to the
> "Terminal Services" on Windows. It looks like the problem is not
> there if the Terminal Services has not been installed/started.

I can confirm this observation.  It doesn't matter if the TS services
are started or not.  Just by having TS installed, certain Cygwin
processes crash.  In my case I can observe crashes in bash, grep, and
GDB, as soon as TS is installed.  However, other applications run fine,
tcsh, vim, all from coreutils as far as I can see...

The crashes don't occur in Cygwin, but in the application code.  As I
said, one of the crashing apps is bash.  I created a full debug bash
version and a special debug version of GDB which, for some reason, runs
fine, in contrast to the net release version of GDB.  What happens is
that some arbitrary application function is called from main() and the
first instruction in this function is the opcode for storing the frame
pointer on the stack, `push %ebp'.  This is, in theory, an entirely
harmless operation.  The stack and register content before and after the
crash are looking absolutely normal.  The push does neither operate on
an invalid address nor on a page boundary, nor is it misaligned.  It's
just a push to some arbitrary address within an existing stack page.

Another strange effect is that even teeny little changes to the
application code (adding a `puts("hello");' or something) result in
entirely different function calls to crash.  The only constant factor is
that it's always the first assembler instruction in some application
function.

For testing I tried to disabled SEH and the Ctrl-C handler in Cygwin,
but the crashes persist.

This puzzles me no end.  Here's the only way I found so far to get rid
of the crashes: Remove Terminal Services and reboot the machine.
Reinstall TS and you're back to square one.


Any hints or help to debug this weird phenomenon are gratefully
appreciated.


Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Project Co-Leader          cygwin AT cygwin DOT com
Red Hat

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