Various systems and methods for generating a mapping binary file are described herein. In one example, a method includes mapping a function call from a legacy binary file to a function call from a virtualized namespace binary file using a builder to detect a build file that enables the mapping, the mapping comprising merging an export table from the legacy binary file and an export table from the virtualized namespace binary file. The method can also include storing the mapping of the function call from the legacy binary file to the function call from the virtualized namespace binary file in a mapping binary file and storing, in the mapping binary file, an exception detected from the combination. Furthermore, the method can include storing the mapping binary file in a storage location accessible by a loader.