PRB: Linker Generates L2048 for Overlaid Programs

• Microsoft FORTRAN for MS-DOS, versions 5.0 and 5.1

SYMPTOMS

LINK.EXE versions 5.3 and later provided with Microsoft C/C++ products support both the dynamic MOVE style overlays and the old method that uses the Static Overlay Manager. FORTRAN customers who attempt to link overlaid programs using these versions of the linker may encounter the following errors:

   LINK : error L2048: Microsoft Overlay Manager module not found
   LINK : warning L4038: program has no starting address

CAUSE

The linker versions 5.3x and later support MOVE overlays by default. The MOVE overlay support code is not present in the FORTRAN run-time library, and therefore these errors are generated.

RESOLUTION

There are three ways to resolve this problem:

• Use the version of LINK that is provided with the FORTRAN compiler.

  -or-

• Use the /OLDOVERLAY (or just /OLD) with these versions of LINK to allow the linker to correctly link using the Static Overlay Manager. The resulting program cannot be debugged because CodeView 4.x cannot debug statically linked programs, and CodeView 4.x must be used to debug applications linked with linker version 5.3x or later.

  -or-

• Use the MOVE overlay technology provided with the Microsoft C/C++ products. The C/C++ MS-DOS run-time library must be linked to the FORTRAN object modules because the MOVE Overlay Manager code is not provided with the FORTRAN run-time library. The resulting code can be debugged using CodeView 4.x. However, because CodeView 4.x does not have a FORTRAN expression evaluator, some of the CodeView functionality is limited. The preferred way of specifying MOVE overlays is via a module definition file; however, the parenthesis syntax of static overlays is also supported.

MORE INFORMATION

The following code samples and the makefile demonstrate how to use MOVE overlays with FORTRAN modules:

Sample Code #1

A.FOR

      print*, 'in root'
      call b
      stop 'terminating in root'
      end

Sample Code #2

B.FOR

      subroutine b
      print*, 'in b'
      call c
      return
      end

Sample Code #3

C.FOR

      subroutine c
      print*, 'in c'
      return
      end

Sample Code #4

MAKEFILE

all: a.exe

.for.obj:

 fl /c /Zi /Od $<