Date: Fri, 26 May 2006 10:59:42 -0700
To: cygwin AT cygwin DOT com
Subject: problem + workaround: system shared memory version mismatch detected
Message-ID: <20060526175942.GB18274@true>
Reply-To: noel AT burton-krahn DOT com
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From: noel AT natnix DOT com
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Problem:

Running an older cygwin app can cause newer cygwin apps to fail with
"system shared memory version mismatch detected"

To Reproduce:

1) start a newer cygwin bash shell.  I tested cygwin version 1.5.19-4.

2) run an app that uses an older cygwin1.dll.  My app used
   cygwin1.dll.  File->Properties on the old cygwin1.dll revealed
   BuildDate: 2004-11-10 08:34, Product Version: 1.5.12.

3) Go back to the running newer bash shell, and try to run something.
   It will fail with "system shared memory version mismatch detected",
   like this:

bash-1.5.19-4$ ls
      2 [main] ? (2388) c:\cygwin\bin\bash.exe: *** fatal error - system
shared memory version mismatch detected - 0x75BE0074/0x75BE0096.
This problem is probably due to using incompatible versions of the
cygwin DLL.
Search for cygwin1.dll using the Windows Start->Find/Search facility
and delete all but the most recent version.  The most recent version
*should*
reside in x:\cygwin\bin, where 'x' is the drive on which you have
installed the cygwin distribution.  Rebooting is also suggested if you
are unable to find another cygwin DLL.
-935119192 [main] bash 3436 child_copy: stack write copy failed,
0x22E950..0x230000, done 0, windows pid 2287748, Win32 error 5
bash: fork: No error

Cause:

cygwin1.dll creates a shared memory segment used by all cygwin apps.
The older cygwin1.dll trashes that shared memory segment, causing
newer cygwin apps to fail.

Workaround:

To get out of the crashing state, kill all cygwin apps and restart
them.  You don't have to restart your whole computer, you just have to
get the newer cygwin1.dll to recreate the shared memory segment.
 
Try deleting the old cygwin1.dlls and make sure the newest cygwin1.dll
is in your path.  Hopefully your older app will still work with the
newer cygwin1.dll.


Hope that helps!

--Noel


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