A VXD that was built in Visual C++ version 5.0 or a later version may fail to load in Windows 95 or Windows 98 if the VXD contains constant data (199295)


The information in this article applies to:

  • Microsoft Visual C++, 32-bit Enterprise Edition 4.2, when used with:
    • the operating system: Microsoft Windows 95
    • the operating system: Microsoft Windows 98
  • Microsoft Visual C++, 32-bit Enterprise Edition 5.0, when used with:
    • the operating system: Microsoft Windows 95
    • the operating system: Microsoft Windows 98
  • Microsoft Visual C++, 32-bit Enterprise Edition 6.0, when used with:
    • the operating system: Microsoft Windows 95
    • the operating system: Microsoft Windows 98
  • Microsoft Visual C++, 32-bit Professional Edition 4.2, when used with:
    • the operating system: Microsoft Windows 95
    • the operating system: Microsoft Windows 98
  • Microsoft Visual C++, 32-bit Professional Edition 5.0, when used with:
    • the operating system: Microsoft Windows 95
    • the operating system: Microsoft Windows 98
  • Microsoft Visual C++, 32-bit Professional Edition 6.0, when used with:
    • the operating system: Microsoft Windows 95
    • the operating system: Microsoft Windows 98
  • Microsoft Visual C++, 32-bit Learning Edition 6.0, when used with:
    • the operating system: Microsoft Windows 95
    • the operating system: Microsoft Windows 98
  • Microsoft Visual C++ .NET (2002), when used with:
    • the operating system: Microsoft Windows 98
  • Microsoft Visual C++ 2005 Express Edition, when used with:
    • the operating system: Microsoft Windows 95
    • the operating system: Microsoft Windows 98
This article was previously published under Q199295

SYMPTOMS

A VXD built in Visual C++ version 5.0 or later, may fail to load in the Windows 95 or Windows 98 operating system if it contains constant data.

The same VXD built with Visual C++ version 4.2 may not show this behavior.

CAUSE

The problem stems from differences in the way the compiler versions handle constant data. The 4.2 compiler erroneously grouped constant data with all other data. Hence, all data appeared in the LDATA section in the object.

Later compilers, starting with version 5.0, correctly treat constant data as separate read only data and place it in the .rdata section. Because of this, the VXD fails to load, unable to recognize the new section.

The Visual C++ .NET Linker issues an LNK4212 warning for this condition.

RESOLUTION

Use any one of the following two workarounds:
  • Add the following pragma in the source file where constant data is declared:
        #pragma const_seg("_LDATA")

    Add the following linker switch:
        /merge:.rdata=_LDATA

STATUS

This behavior is by design.
Modification Type:MajorLast Reviewed:1/11/2006
Keywords:kbtshoot kbCompiler kbprb KB199295 kbAudDeveloper
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