ModelSim SE User's Manual - Electrical and Computer Engineering

Referencing source files with location maps
Using location mapping
Referencing source files with location maps UM-67
Pathnames to source files are recorded in libraries by storing the working directory from
which the compile is invoked and the pathname to the file as specified in the invocation of
the compiler. The pathname may be either a complete pathname or a relative pathname.
ModelSim tools that reference source files from the library locate a source file as follows:
If the pathname stored in the library is complete, then this is the path used to reference
the file.
If the pathname is relative, then the tool looks for the file relative to the current working
directory. If this file does not exist, then the path relative to the working directory stored
in the library is used.
This method of referencing source files generally works fine if the libraries are created and
used on a single system. However, when multiple systems access a library across a
network, the physical pathnames are not always the same and the source file reference rules
do not always work.
Location maps are used to replace prefixes of physical pathnames in the library with
environment variables. The location map defines a mapping between physical pathname
prefixes and environment variables.
ModelSim tools open the location map file on invocation if the MGC_LOCATION_MAP
(UM-521) environment variable is set. If MGC_LOCATION_MAP is not set, ModelSim
will look for a file named "mgc_location_map" in the following locations, in order:
the current directory
your home directory
the directory containing the ModelSim binaries
the ModelSim installation directory
Use these two steps to map your files:
1 Set the environment variable MGC_LOCATION_MAP to the path to your location map
file.
2 Specify the mappings from physical pathnames to logical pathnames:
$SRC
/home/vhdl/src
/usr/vhdl/src
$IEEE
/usr/modeltech/ieee
ModelSim SE User’s Manual