[osgeo4w-dev] Compressing osgeo4w-setup.exe

Jeff McKenna jmckenna at gatewaygeomatics.com
Mon May 31 13:43:34 EDT 2010

Hello devs,

We've recently hit a wall when compiling a new osgeo4w-setup.exe file. 
Following the steps in the cygwin README, when compressing the exe with 
the UPX utility (the goal is to get the 9MB exe down to approximately 
400KB) the following error is thrown:

     CantPackException: TLS callbacks are not supported

I dug into this issue and wow a lot of people are hitting this wall (UPX 
users, Cygwin team, RedHat team).  Eventually I found a thread on the 
cygwin-apps mailing, and one of the messages states that for the current 
mingw-runtime version (3.18) TLS callbacks are now the default, and this 
causes problems for UPX since it does not allow TLS callbacks 
(http://www.cygwin.com/ml/cygwin-apps/2010-03/msg00075.html).  Long long 
long story short, the current workout for compressing osgeo4w-setup.exe 
is to revert to mingw-runtime version 3.17.  I have documented this in 
detail on the SetupDevelopment page (see setup 5: 


Jeff McKenna
MapServer Consulting and Training Services

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