This text describes contribution procedures for adding scripts to
systemtap.examples directory.  Please read before submitting SystemTap
examples.  Discussions take place on the <systemtap@sourceware.org> list.

- general

  The script should do something that normal users of SystemTap might
  like to do, such as show which processes have system calls that time
  out or show which memory accesses cause page faults.  Scripts that
  check that some aspect of SystemTap operates correctly, but would
  never be used by a regular user should go in one of the other
  testsuite directories.

- copyright

  You must designate the appropriate copyright holder for your
  contribution.  The copyright holder is assumed to agree with the
  general licensing terms (GPLv2+).

- coding style

  Abide by the general formatting of the code for SystemTap.  The
  code base generally follows the GNU standards in usermode code and
  the Linux kernel standards in runtime code.

  - Try to keep the lines shorter than 80 characters long.
  - Make use of SystemTap functions to factor out common idioms in code.
  - Use tapset probe points rather than raw function names.
  - Make scripts portable by avoiding probes by file and line number.
  - Avoid unnecessary use of guru mode (-g) in the examples.
  - Make the file executable and use the following line at the
    beginning of the script to select the proper interpreter:

    #! /usr/bin/env stap


- Describe the example

  Each example script has a description in a .meta file that provide
  an easy-to-parse format that describes various aspect of the example
  script. The .meta file has the same base name as the example script.
  The .meta file is parsed to generate a web page listing all the
  available examples; the webpage is available at:
  http://sourceware.org/systemtap/examples/.  The .meta file also
  describes how to run the compiled example script for testing. This
  ensures that the example is frequently run to verify it works on a
  wide range of platforms.

  The meta file may contain the following elements. Each element (key
  and value) are on one line. If a key can have a list of values, the
  list elements are separated by spaces.  Only fields marked with "@"
  below are meaningful enough and used by the index-generator, so
  a .meta file can be quite small.  The generator script
      perl examples-index-gen.pl
  should be run whenever .meta/.txt files are modified.  Note, this
  will require perl DBI.


+---- @ means required
|
v

@ title: Descriptive title for the script (required)
@ name: the file name for the script, e.g. iotime.stp (required)
  version: versioning if any fixes and developed can be identified
           (optional)
  author: name of author(s), if known (optional)
  exclusivearch: Stated if the script can only run on some arches
                 this concept borrowed from rpm, matches types for
                 rpm: x86 i386 x86_64 ppc ppc64, s390 (optional)
  requires: Some scripts may require software to be available. In some
            cases may need version numbering, e.g. kernel >= 2.6
            Can have multiple "requires:" tags. (optional)
@ keywords: List of likely words to categorize the script (required)
            keywords are separated by spaces.  Please don't be
            unnecessarily innovative with keywords.  Tag really good
            examples with the "_best" keyword for highlighting in indexes.
  subsystem: List what part of the kernel the instrumentation probes
             (optional), similar to keywords
  application: when user-space probing becomes available (optional)
               a script might probe a particular application
               this tag indicates the applicaton
  status: describes the state of development for the script (optional)
          proposed      just an idea
          experimental  an implemented idea, but use at own risk
          alpha
          beta
          production    should be safe to use
  exit: how long does the script run? (optional)
        fixed           exits in a fixed amount of time
        user-controlled       exits with "cntrl-c"
        event-ended                 exits with some arbitrary event
  output: what kind of output does the script generate? (optional)
          trace histogram graph sorted-list batch timed on-exit
  scope: How much of the processes on the machine does the script
         watch? (required) system-wide, process or per-socket
  arg_[0-9]+: Describe what the arguments into the script are.
              (optional)
@ description: A text description what the script does. (required)
  test_support: How to check that the example is applicable.  Run by
                'sh -c COMMAND'. (e.g. stap -l needed.probe)
  test_check: How to check that the example compiles.  Run by
              'sh -c COMMAND'. (e.g. stap -p4 iotime.stp)
  test_installcheck: How to check that the example runs.  Run by
                     'sh -c COMMAND'.
                     (e.g. stap iotime.stp -T 1)
@ usage: A sample invocation of the script, if more informative than
         the test_* ones.
@        As an alternative, a SAMPLE.txt file beside the .meta/.stp
         files can be used to give longer freeform usage examples
         for the script.


- Testing of the example script

  To enable automated testing, include the "test_support", "test_check",
  and/or "test_installcheck" fields in the meta file.  Run the examples
  subset of the testsuite with
  % make check RUNTESTFLAGS=check.exp
  and/or
  # make installcheck RUNTESTFLAGS=check.exp

  Note that the check.exp test script checks for an optional tcl file
  that can check to see if the example is applicable to the system,
  somewhat analogous to the 'test_support' key mentioned above.


- Review, revision, and submission of the example script

  When you have a SystemTap script that should be included as an
  example, submit it to the SystemTap mailing list,
  systemtap@sourceware.org for review. Even if the script is not
  ready for submission as an example, feel free to ask questions or
  discuss the work-in-progress script with other people working with
  SystemTap.

