RE: [GD-Windows] Loading new DLLs on old Windows

[Simon O'C. <si...@sc...>]

Hi Andras,


The subsystem for a DLL is controlled by the /SUBSYSTEM: linker option in
your project settings.


For a DLL project, this will be set to /SUBSYSTEM:WINDOWS.


The /SUBSYSTEM: linker option has an **OPTIONAL** subsystem version
parameter (e.g. /SUBSYSTEM:WINDOWS,5.01). This optional parameter allows you
to specify the _minimum_ OS version that the DLL requires to be run. 

You'll find a list of OS version numbers in the documentation for
OSVERSIONEX. Some examples are:
Windows 95:    4.0
Windows 98:    4.10
Windows ME:    4.90
Windows 2000:  5.0
Windows XP:    5.1 (5.01)

Note that the OS version number comes as two parts, major (4, 5 etc) and
minor (0, 10, 90, 1 etc). The point isn't a decimal point so 5.1 is the same
as 5.01 (the "minor" number is 1).


If you (or your development tools) do *not* specify the optional version
parameter at the end of the /SUBSYSTEM:WINDOWS option, a default subsystem
of 4.00 will be used, regardless of your development tool or OS. [NB: only
for x86  code targets, for Itanium code targets this is 5.01]

So a DLL created with Visual Studio .NET 2003 on a WindowsXP machine for
example will still have a subsystem of 4.00.


The only time you'll encounter a DLL under Win32 OSes that has a subsystem
that is different than 4.00 is if that DLL absolutely requires that version
of Windows.


You can view the subsystem of a DLL using Dependency Walker (it comes with
the platform SDK, depends.exe). DUMPBIN should tell you this too.


To change the subsystem of an existing DLL that you don't have the
sourcecode to (i.e. when you aren't able to alter the /SUBSYSTEM option),
you can change it using EDITBIN.


So in short, all that part of the documentation is saying is "if the DLL
specifies that it needs a newer version of Windows than the one currently
installed (if 9x) then the LoadLibrary() call will fail".


HTH

Cheers,

Simon O'Connor
Programmer @ Acclaim
& Microsoft DirectX MVP  

> -----Original Message-----
> From: gam...@li... 
> [mailto:gam...@li...] On 
> Behalf Of Andras Balogh
> Sent: 10 February 2004 16:31
> To: gam...@li...
> Subject: [GD-Windows] Loading new DLLs on old Windows
> 
> MSDN says:
> 
> "Windows Me/98/95: If you are using LoadLibrary to load a 
> module that contains a resource whose numeric identifier is 
> greater than 0x7FFF, LoadLibrary fails. If you are attempting 
> to load a 16-bit DLL directly from 32-bit code, LoadLibrary 
> fails. If you are attempting to load a DLL whose subsystem 
> version is greater than 4.0, LoadLibrary fails. If your 
> DllMain function tries to call the Unicode version of a 
> function, LoadLibrary fails."
> 
> Now, I believe that my DLLs' subsystem version is greater 
> than 4.0 (how can I check?). How can I make it work on 
> Win95/98/ME?? Is there a linker option? Or some other workaround?
> 
> 
> Thanks,
> 
> Andras
> 
> 
> 
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