BUG: MASM sample SYSINFO Error: L1101 invalid object module

The information in this article applies to:

• Microsoft Macro Assembler for MS-DOS, version 6.11, 6.11c, 6.11d
• Microsoft Macro Assembler for Windows NT, version 6.11, 6.11c, 6.11d

SYMPTOMS

When you build the MASM WINDLL sample DLL project, SYSINFO generates this linker error:

   SYSINFO.OBJ(SYSINFO.ASM) : fatal error L1101: invalid object module

CAUSE

This is due to a problem in the EXPDEF record in the .obj file created when the EXPORT keyword is used to modify the attributes of a PROC.

RESOLUTION

This problem can be avoided in these MASM versions in one of several ways:

• Do not use the EXPORT keyword. Remove the EXPORT keyword from the SYSINFO.ASM source file (four places). In this sample, the DLL's functions are exported in the .def file, so the EXPORT keyword is not necessary. This is the preferred solution.

  -or-

• Use a linker newer than LINK version 5.31.009, such as a linker that ships with a 16-bit Visual C++. The WINDLL sample, which contains the SYSINFO DLL, also contains the SYSDATA application used to call this DLL. To build the application, some portion of the Windows 3.1 SDK is required (the resource compiler) in addition to MASM. The most common place to get this additional requirement is from Visual C++ version 1.0 Professional edition or Visual C++ version 1.5x. By placing the Visual C++ Bin directory in the path before the MASM BIN directory, the resource compiler will be found. In addition, the newer linker will be used instead of MASM's linker.

  In this solution, the .obj file still has a problem, but the linker does not stop the build. Instead it gives an L4059 warning that can be ignored. Because the .obj file has the problem in one of the EXPDEF records, the functions still need to be exported via the .def file. That is why the first solution is the preferred method.

  -or-

• Run MASM in a MS-DOS box under Windows version 3.1x (16-bit Windows). The problem seems to be sensitive to the environment in which MASM is run. In pure MS-DOS and under Windows NT, MASM version 6.11 always displays this problem, but when it is run in an MS-DOS box under Windows version 3.1x, no error occurs. In the latter case, the .obj file does not contain the error.

STATUS

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article. We are researching this bug and will post new information here in the Microsoft Knowledge Base as it becomes available.

MORE INFORMATION

This problem does not appear in MASM version 6.11a with this sample. However it is likely that a problem still exists creating an EXPDEF record using the EXPORT keyword in version 6.11a and the above resolutions will apply.