Hello,

I just discovered that there's one more mechanism that automatically adds
dependencies between packages, called 'depchains'. Here's a suggested
documentation change to '4.4. Automatically Added Runtime Dependencies'
to document it.

The introductory paragraph is changed to mention 'depchains', and a new bullet
is added to document it:

  The OpenEmbedded build system automatically adds common types of runtime
  dependencies between packages, which means that you do not need to explicitly
  declare the packages using RDEPENDS. Three automatic mechanisms exist
  (shlibdeps, pcdeps, and depchains) that handle shared libraries, package
  configuration (pkg-config) modules, and -dev and -dbg packages, respectively.
  For other types of runtime dependencies, you must manually declare the
  dependencies. 
  
    * shlibdeps: ...
  
    * pcdeps: ...
  
    * depchains: If a package foo depends on a package bar, then foo-dev and
      foo-dbg are also made to depend on bar-dev and bar-dbg, respectively.
      Taking the -dev packages as an example, the bar-dev package might provide
      headers and shared library symlinks needed by foo-dev, which shows the need
      for a dependency between the packages.
  
      The dependencies added by depchains are in the form of [RRECOMMENDS].
  
      Note {
      By default, foo-dev also has an RDEPENDS-style dependency on foo, because
      the default value of RDEPENDS_${PN}-dev (set in bitbake.conf) includes
      "${PN}".
      }
  
      To ensure that the dependency chain is never broken, -dev and -dbg packages
      are always generated by default, even if the packages turn out empty. See
      [ALLOW_EMPTY].


Cheers,
Ulf