4 files changed, 81 insertions, 6 deletions

diff --git a/documentation/adt-manual/adt-package.xml b/documentation/adt-manual/adt-package.xml
index f7b236f8d5..c035c2d011 100644
--- a/documentation/adt-manual/adt-package.xml
+++ b/documentation/adt-manual/adt-package.xml
@@ -52,6 +52,13 @@
         See the configuration file for details.
     </para>
 
+    <note>
+        For build performance information related to the PMS, see
+        <ulink url='http://www.yoctoproject.org/docs/1.1/poky-ref-manual/poky-ref-manual.html#ref-classes-package'>Packaging - <filename>package*.bbclass</filename></ulink> 
+        in <ulink url='http://www.yoctoproject.org/docs/1.1/poky-ref-manual/poky-ref-manual.html'>
+        The Yocto Project Reference Manual</ulink>.
+    </note>
+
     <para>
         As an example, consider a scenario where you are using OPKG and you want to add 
         the <filename>libglade</filename> package to the target sysroot.
diff --git a/documentation/poky-ref-manual/ref-classes.xml b/documentation/poky-ref-manual/ref-classes.xml
index cf396800df..93e9ea8d43 100644
--- a/documentation/poky-ref-manual/ref-classes.xml
+++ b/documentation/poky-ref-manual/ref-classes.xml
@@ -265,17 +265,59 @@
         The packaging classes add support for generating packages from a build's
         output. 
         The core generic functionality is in <filename>package.bbclass</filename>.
-        The code specific 
-        to particular package types is contained in various sub-classes such as
+        The code specific to particular package types is contained in various sub-classes such as
         <filename>package_deb.bbclass</filename>, <filename>package_ipk.bbclass</filename>,
         and <filename>package_rpm.bbclass</filename>. 
         Most users will want one or more of these classes.
+    </para>
+ 
+    <para>
         You can control the list of resulting package formats by using the 
         <filename><link linkend='var-PACKAGE_CLASSES'>PACKAGE_CLASSES</link></filename> 
-        variable. 
-        The first class listed in this  variable is be used for image generation. 
+        variable defined in the <filename>local.conf</filename> configuration file 
+        found in the Yocto Project file's <filename>conf</filename> directory. 
+        When defining the variable, you can specify one or more package types.
         Since images are generated from packages, a packaging class is 
         needed to enable image generation.
+        The first class listed in this variable is used for image generation. 
+    </para>
+
+    <para>
+        The package class you choose can affect build-time performance and has space
+        ramifications.
+        In general, building a package with RPM takes about thirty percent more time as 
+        compared to using IPK to build the same or similar package.
+        This comparison takes into account a complete build of the package with all 
+        dependencies previously built.
+        The reason for this discrepancy is because the RPM package manager creates and 
+        processes more metadata than the IPK package manager.
+        Consequently, you might consider setting <filename>PACKAGE_CLASSES</filename>
+        to "package_ipk" if you are building smaller systems.
+    </para>
+
+    <para>
+        Keep in mind, however, that RPM starts to provide more abilities than IPK due to 
+        the fact that it processes more metadata.
+        For example, this information includes individual file types, file checksum generation
+        and evaluation on install, sparse file support, conflict detection and resolution
+        for multilib systems, ACID style upgrade, and repackaging abilities for rollbacks.
+    </para>
+
+    <para>
+        Another consideration for packages built using the RPM package manager is space.
+        For smaller systems, the extra space used for the Berkley Database and the amount 
+        of metadata can affect your ability to do on-device upgrades.
+    </para>
+
+    <para>
+        You can find additional information on the effects of the package class at these 
+        two Yocto Project mailing list links:
+        <itemizedlist>
+            <listitem><para><ulink url='https://lists.yoctoproject.org/pipermail/poky/2011-May/006362.html'>
+                https://lists.yoctoproject.org/pipermail/poky/2011-May/006362.html</ulink></para></listitem>
+            <listitem><para><ulink url='https://lists.yoctoproject.org/pipermail/poky/2011-May/006363.html'>
+                https://lists.yoctoproject.org/pipermail/poky/2011-May/006363.html</ulink></para></listitem>
+        </itemizedlist>
     </para>
 </section>
 
diff --git a/documentation/poky-ref-manual/ref-variables.xml b/documentation/poky-ref-manual/ref-variables.xml
index 7f51fc9885..0bde65915c 100644
--- a/documentation/poky-ref-manual/ref-variables.xml
+++ b/documentation/poky-ref-manual/ref-variables.xml
@@ -679,7 +679,19 @@
 
         <glossentry id='var-PACKAGE_CLASSES'><glossterm>PACKAGE_CLASSES</glossterm>
             <glossdef>
-                <para>Specifies the list of resulting package formats.</para>
+                <para>This variable, which is set in the <filename>local.conf</filename> configuration
+                    file found in the Yocto Project file's <filename>conf</filename> directory,
+                    specifies the package manager to use when packaging data.
+                    You can provide one or more arguments for the variable with the first 
+                    argument being the package manager used to create images:
+                    <literallayout class='monospaced'>
+     PACKAGE_CLASSES ?= "package_rpm package_deb package_ipk"
+                    </literallayout>
+                    For information on build performance effects as a result of the 
+                    package manager use, see
+                    <link linkend='ref-classes-package'>Packaging - <filename>package*.bbclass</filename></link>
+                    in this manual.
+                </para>
             </glossdef>
         </glossentry>
 
diff --git a/documentation/yocto-project-qs/yocto-project-qs.xml b/documentation/yocto-project-qs/yocto-project-qs.xml
index 62280b619f..c95e1a02ab 100644
--- a/documentation/yocto-project-qs/yocto-project-qs.xml
+++ b/documentation/yocto-project-qs/yocto-project-qs.xml
@@ -330,7 +330,8 @@
              <filename>conf/local.conf</filename> file.</para></listitem>
          </itemizedlist>
          <para>
-             Take some time to examine your <filename>conf/local.conf</filename> file.  
+             Take some time to examine your <filename>conf/local.conf</filename> file found in the
+             Yocto Project file's <filename>conf</filename>.  
              The defaults should work fine.  
              However, if you have a multi-core CPU you might want to set the variable
              BB_NUMBER_THREADS equal to twice the number of processor cores your system has.
@@ -338,6 +339,19 @@
              Setting these variables can significantly shorten your build time.
              By default, these variables are commented out.
          </para>
+
+        <para>
+            Another consideration before you build is the package manager used when creating 
+            the image. 
+            By default, the Yocto Project build system uses the RPM package manager.
+            You can control this configuration by using the 
+            <filename><ulink url='http://www.yoctoproject.org/docs/1.1/poky-ref-manual/poky-ref-manual.html#var-PACKAGE_CLASSES'>PACKAGE_CLASSES</ulink></filename> variable.  
+             For additional package manager selection information, see 
+             <ulink url='http://www.yoctoproject.org/docs/1.1/poky-ref-manual/poky-ref-manual.html#ref-classes-package'>Packaging - <filename>package*.bbclass</filename></ulink> in 
+             <ulink url='http://www.yoctoproject.org/docs/1.1/poky-ref-manual/poky-ref-manual.html'>
+             The Yocto Project Reference Manual</ulink>.
+        </para>
+
          <para>
              Continue with the following command to build an OS image for the target, which is 
              <filename>core-image-sato</filename> in this example.