Hello,

Nothing currently hints at that the .dot files are easy to read directly in a text editor. The resulting graphs are completely unreadable without pruning and processing, so knowing this can be extremely useful.

I suggest the following changes:

 * Move '2.3.5. Dependency Graphs' to 2.3.3. and rename it to "2.3.3. Viewing Dependencies". This makes the name consistent with the sections above it.

 * Rewrite it as follows:

  Sometimes it can be hard to see why BitBake wants to build other recipes before
  the one you have specified. To generate dependency information for a recipe,
  run the following command:
  
    $ bitbake -g recipename
  
  This command writes the following files in the current directory:
  
    * pn-buildlist: A list of recipes/targets involved in building `recipename`.
      "Involved" here means that at least one task from the recipe would need to
      run when building `recipename` from scratch. Targets that are in
      [ASSUME_PROVIDED] are not listed.
  
    * pn-depends.dot: A graph showing dependencies between build-time targets
      (recipes).
  
    * package-depends.dot: A graph showing (known) dependencies between runtime
      targets.
  
    * task-depends.dot: A graph showing dependencies between tasks.
  
  The graphs are in
  [DOT](https://en.wikipedia.org/wiki/DOT_%28graph_description_language%29)
  format and can be converted to images using e.g. the 'dot' tool from
  [Graphviz](http://www.graphviz.org/).
  
  Note {
  DOT files use a plain text format. The graphs generated by 'bitbake -g' are
  often so large as to be impossible to read without special pruning (e.g. with
  bitbake's -I option) and processing, but the corresponding .dot files are often
  still easy to read and can provide useful information.
  
  As an example, task-depends.dot contains lines like the following:
  
    "libxslt.do_configure" -> "libxml2.do_populate_sysroot"
  
  The above line tells us that libxslt's do_configure task depends on libxml2's
  do_populate_sysroot task (a normal [DEPENDS] dependency between the recipes).
  }
  
  A different way to view dependency information is with the following command:
  
    $ bitbake -g -u depexp recipename
  
  This will pop up a GUI window where build- and runtime dependencies can be
  viewed for the recipes involved in building recipename.


I originally wanted to document exactly what information pn-depends.dot and package-depends.dot contain as well, but to be honest it escapes me (and I got frustrated trying to reverse-engineer it). It's not clear at all what stuff like "virtual:native:" and filled vs. dashed vs. dotted edges means. A much more concrete and detailed description is needed, but that's for another ticket in that case.

Cheers,
Ulf