4.4 Simics's Search Path

Many Simics commands will look up files based on the current directory. When Simics is launched from the command line, the current directory is the current directory of the shell Simics was launched from. When Simics is launched by double clicking its icon, the current directory is the project directory. This may be impractical when writing scripts or building new configurations, so Simics provides two features to ease directory handling:

• Simics recognizes some special path markers that are translated before being used:

  %simics%

  This path marker causes Simics to locate the file (following the marker) in the project directory or in any of the installed packages. If not found in the project directory, Simics will start searching in the newest package, i.e. the one with the highest build-id number.

  For example, %simics%/scripts/foo.simics could be translated to:

  Windows:

  C:\Program Files\Simics\Simics 6\Simics 6.0.1\scripts\foo.simics

  Linux:

  /opt/simics/simics-6/simics-6.0.1/scripts/foo.simics

  Note that if you change the version of Simics, %simics% will change as well, so you should use it to refer only to files that you know are present in all Simics versions. Notice also that %simics% has no meaning if no file can be found. You can use the command lookup-file to find out how the path will be translated.

  %script%

  Translated to the directory where the currently running script is located. A possible usage is to let a script call another one in the same directory, independently of what the current directory is.

  For example, if the directory baz contains the scripts foo.simics and bar.simics, even if the user uses Simics with another current directory, it will be possible for foo.simics to call bar.simics by issuing the command:

  run-command-file %script%/bar.simics

  %simics% and %script% are always translated to absolute paths, so they never interact with the next feature, called Simics's search path. One consequence is that they must always be used in double quotes "%simics%/targets/qsp-x86/images" to ensure that escaped characters such as spaces are used correctly.

• Simics has a list of paths called Simics's search path where files will be looked up when using some specific commands (among others, load-binary, load-file, run-command-file, and run-python-file) and a number of classes (such as the image class and the tftp server implementation in the service-node). The file is first looked up in the current directory, then in all entries of Simics's search path, in order.

  Windows:

  Let us assume for example that Simics's search path contains
  C:\Users\joe\scripts\
  and that the current directory is
  C:\Users\joe\project\
  If the command:

  simics> run-command-file test/start-test.simics

  is issued, Simics will look for the following files to run:

  1. C:\Users\joe\project\test\start-test.simics
  2. C:\Users\joe\scripts\test\start-test.simics

  Linux:

  Let us assume for example that Simics's search path contains
  /home/joe/scripts/ and that the current directory is /home/joe/project. If the command:

  simics> run-command-file test/start-test.simics

  is issued, Simics will look for the following files to run:

  1. /home/joe/project/test/start-test.simics
  2. /home/joe/scripts/test/start-test.simics

Simics's search path can be manipulated using the add-directory, clear-directories and list-directories commands. Simics's search path is also used when looking for image files belonging to checkpoints or new configurations. This is described in section Image Search Path.

Remember that setting a CLI variable to a path with %simics% or %script% does not in itself evaluate the path marker. This means that the path marker may evaluate to another directory than is anticipated. The following two lines evaluate quite differently:

$just_a_string = "%script%/images/my_image"
$absolute_path = (lookup-file "%script%/images/my_image")

The first CLI variable reads the given text and may evaluate to wherever. The second variable is evaluated locally and reads the absolute path for the my_image file that is located nearby the script.