/Fm (Name Mapfile)
Tells the linker to produce a mapfile containing a list of segments in the order in which they appear in the corresponding .exe file or DLL.
By default, the mapfile is given the base name of the corresponding C or C++ source file with a .MAP extension.
Specifying /Fm has the same effect as if you had specified the /MAP (Generate Mapfile) linker option.
If you specify /c (Compile Without Linking) to suppress linking, /Fm has no effect.
Global symbols in a mapfile usually have one or more leading underscores because the compiler adds a leading underscore to variable names. Many global symbols that appear in the mapfile are used internally by the compiler and the standard libraries.
To set this compiler option in the Visual Studio development environment
Open the project's Property Pages dialog box. For details, see How to: Open Project Property Pages.
Click the C/C++ folder.
Click the Command Line property page.
Type the compiler option in the Additional Options box.
To set this compiler option programmatically