overview-manual/concepts: add UNPACKDIR in the directory description

Mention that UNPACKDIR is used as a location to unpack the source code,
and that S is the final location of the source code. This is
deliberately vague, because as there are multiple instances of how these
directories can be defined and used.

The proper explanation of how the UNPACKDIR and S directories interact
is left to the reference manual, under the UNPACKDIR variable
description.

(From yocto-docs rev: 85e738e4c0e62f69699fff4bb0482ee3e3121496)

Signed-off-by: Antonin Godard <antonin.godard@bootlin.com>
(cherry picked from commit 39ca56c3a3a5218ca73c7ced212b2ee89428a2d1)
Signed-off-by: Antonin Godard <antonin.godard@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

1 files changed, 9 insertions, 6 deletions

diff --git a/documentation/overview-manual/concepts.rst b/documentation/overview-manual/concepts.rst
index 833d6c8ab7..9ff9785bdd 100644
--- a/documentation/overview-manual/concepts.rst
+++ b/documentation/overview-manual/concepts.rst
@@ -704,10 +704,10 @@ a defined structure. For additional general information on the
 the Yocto Project Reference Manual.
 
 Each recipe has an area in the :term:`Build Directory` where the unpacked
-source code resides. The :term:`S` variable points to this area for a recipe's
-unpacked source code. The name of that directory for any given recipe is
-defined from several different variables. The preceding figure and the
-following list describe the :term:`Build Directory`'s hierarchy:
+source code resides. The :term:`UNPACKDIR` variable points to this area for a
+recipe's unpacked source code, and has the default ``sources-unpack`` name. The
+preceding figure and the following list describe the :term:`Build Directory`'s
+hierarchy:
 
 -  :term:`TMPDIR`: The base directory
    where the OpenEmbedded build system performs all its work during the
@@ -736,8 +736,11 @@ following list describe the :term:`Build Directory`'s hierarchy:
    -  :term:`PV`: The version of the
       recipe used to build the package.
 
--  :term:`S`: Contains the unpacked source
-   files for a given recipe.
+-  :term:`UNPACKDIR`: Contains the unpacked source files for a given recipe.
+
+-  :term:`S`: Contains the final location of the source code.
+
+   The default value for :term:`BP` is ``${BPN}-${PV}`` where:
 
    -  :term:`BPN`: The name of the recipe
       used to build the package. The :term:`BPN` variable is a version of