An executable file to be run under CodeView 4.00 must first be packed by CVPACK 4.00. The debugging information in the file must be in the form given in the Microsoft Symbolic Debugging Information specification. This is the format supported by current Microsoft compilers and linkers.
Earlier formats of debugging information and CVPACK-packing are not compatible with CodeView 4.00. If an executable file contains debugging information in an earlier format but has not been packed, packing with CVPACK 4.00 is all that is needed for the file to run in CodeView 4.00. However, if the executable file has been packed with an earlier version of CVPACK, you must relink the file.
Executable files packed using CVPACK 4.00 are not compatible with earlier versions of CodeView. The debugging information produced by the Microsoft C Compiler version 7.00 and packed by CVPACK 4.00 is for use with CodeView 4.00 and is not compatible with earlier versions of CodeView.
CVPACK compresses debugging information by removing duplicate type definitions. To be removed by CVPACK, the definitions must be absolutely identical. For example, if a structure defined in two modules contains a pointer to another structure, but the second structure is defined in only one module, the pointer size is unknown in the other module. In this case, CVPACK cannot pack the duplicate structure definitions in the same way, which causes less efficient compression.
CVPACK can pack an executable that is in .COM format. The linker puts debugging information for a .COM file into a file with the same base name as the executable file and with a .DBG extension. When you specify a .COM file to be packed, CVPACK looks for a .DBG file with the same base name and in the same location as the .COM file.