Documentation: poky-ref-manual - Removed all trailing whitespace.

(From yocto-docs rev: 564a28c2501034ea7e2eb16afc43dfaf931b6f6f)

Signed-off-by: Scott Rifenbark <scott.m.rifenbark@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

1 files changed, 217 insertions, 217 deletions

diff --git a/documentation/poky-ref-manual/technical-details.xml b/documentation/poky-ref-manual/technical-details.xml
index 042a96ed87..72689a0e22 100644
--- a/documentation/poky-ref-manual/technical-details.xml
+++ b/documentation/poky-ref-manual/technical-details.xml
@@ -6,7 +6,7 @@
 <title>Technical Details</title>
 
     <para>
-        This chapter provides technical details for various parts of the Yocto Project. 
+        This chapter provides technical details for various parts of the Yocto Project.
         Currently, topics include Yocto Project components and shared state (sstate) cache.
     </para>
 
@@ -14,21 +14,21 @@
     <title>Yocto Project Components</title>
 
     <para>
-        The BitBake task executor together with various types of configuration files form the 
+        The BitBake task executor together with various types of configuration files form the
         OpenEmbedded Core.
         This section overviews the BitBake task executor and the
         configuration files by describing what they are used for and how they interact.
     </para>
-    
-    <para>  
-        BitBake handles the parsing and execution of the data files. 
+
+    <para>
+        BitBake handles the parsing and execution of the data files.
         The data itself is of various types:
     <itemizedlist>
-        <listitem><para><emphasis>Recipes:</emphasis>  Provides details about particular 
+        <listitem><para><emphasis>Recipes:</emphasis>  Provides details about particular
             pieces of software</para></listitem>
-        <listitem><para><emphasis>Class Data:</emphasis>  An abstraction of common build 
+        <listitem><para><emphasis>Class Data:</emphasis>  An abstraction of common build
             information (e.g. how to build a Linux kernel).</para></listitem>
-        <listitem><para><emphasis>Configuration Data:</emphasis>  Defines machine-specific settings, 
+        <listitem><para><emphasis>Configuration Data:</emphasis>  Defines machine-specific settings,
             policy decisions, etc.
             Configuration data acts as the glue to bind everything together.</para></listitem>
     </itemizedlist>
@@ -37,17 +37,17 @@
         section in the Yocto Project Development Manual.
     </para>
 
-    <para> 
+    <para>
         BitBake knows how to combine multiple data sources together and refers to each data source
         as a layer.
-        For information on layers, see the 
-        "<ulink url='&YOCTO_DOCS_DEV_URL;#understanding-and-creating-layers'>Understanding and 
+        For information on layers, see the
+        "<ulink url='&YOCTO_DOCS_DEV_URL;#understanding-and-creating-layers'>Understanding and
         Creating Layers</ulink>" section of the Yocto Project Development Manual.
     </para>
 
     <para>
         Following are some brief details on these core components.
-        For more detailed information on these components see the 
+        For more detailed information on these components see the
         "<link linkend='ref-structure'>Directory Structure</link>" chapter.
     </para>
 
@@ -57,7 +57,7 @@
         <para>
             BitBake is the tool at the heart of the OpenEmbedded build system and is responsible
             for parsing the metadata, generating a list of tasks from it,
-            and then executing those tasks. 
+            and then executing those tasks.
             To see a list of the options BitBake supports, use the following help command:
             <literallayout class='monospaced'>
      $ bitbake --help
@@ -66,8 +66,8 @@
 
         <para>
             The most common usage for BitBake is <filename>bitbake &lt;packagename&gt;</filename>, where
-            <filename>packagename</filename> is the name of the package you want to build 
-            (referred to as the "target" in this manual). 
+            <filename>packagename</filename> is the name of the package you want to build
+            (referred to as the "target" in this manual).
             The target often equates to the first part of a <filename>.bb</filename> filename.
             So, to run the <filename>matchbox-desktop_1.2.3.bb</filename> file, you
             might type the following:
@@ -76,15 +76,15 @@
             </literallayout>
             Several different versions of <filename>matchbox-desktop</filename> might exist.
             BitBake chooses the one selected by the distribution configuration.
-            You can get more details about how BitBake chooses between different 
-            target versions and providers in the 
+            You can get more details about how BitBake chooses between different
+            target versions and providers in the
             "<link linkend='ref-bitbake-providers'>Preferences and Providers</link>" section.
         </para>
 
         <para>
             BitBake also tries to execute any dependent tasks first.
             So for example, before building <filename>matchbox-desktop</filename>, BitBake
-            would build a cross compiler and <filename>eglibc</filename> if they had not already 
+            would build a cross compiler and <filename>eglibc</filename> if they had not already
             been built.
             <note>This release of the Yocto Project does not support the <filename>glibc</filename>
                 GNU version of the Unix standard C library.  By default, the OpenEmbedded build system
@@ -92,12 +92,12 @@
         </para>
 
         <para>
-            A useful BitBake option to consider is the <filename>-k</filename> or 
-            <filename>--continue</filename> option.  
-            This option instructs BitBake to try and continue processing the job as much 
-            as possible even after encountering an error.  
+            A useful BitBake option to consider is the <filename>-k</filename> or
+            <filename>--continue</filename> option.
+            This option instructs BitBake to try and continue processing the job as much
+            as possible even after encountering an error.
             When an error occurs, the target that
-            failed and those that depend on it cannot be remade.  
+            failed and those that depend on it cannot be remade.
             However, when you use this option other dependencies can still be processed.
         </para>
     </section>
@@ -106,17 +106,17 @@
         <title>Metadata (Recipes)</title>
 
         <para>
-            The <filename>.bb</filename> files are usually referred to as "recipes." 
+            The <filename>.bb</filename> files are usually referred to as "recipes."
             In general, a recipe contains information about a single piece of software.
-            The information includes the location from which to download the source patches 
-            (if any are needed), which special configuration options to apply, 
-            how to compile the source files, and how to package the compiled output. 
+            The information includes the location from which to download the source patches
+            (if any are needed), which special configuration options to apply,
+            how to compile the source files, and how to package the compiled output.
         </para>
 
         <para>
             The term "package" can also be used to describe recipes.
-            However, since the same word is used for the packaged output from the OpenEmbedded 
-            build system (i.e. <filename>.ipk</filename> or <filename>.deb</filename> files), 
+            However, since the same word is used for the packaged output from the OpenEmbedded
+            build system (i.e. <filename>.ipk</filename> or <filename>.deb</filename> files),
             this document avoids using the term "package" when referring to recipes.
         </para>
     </section>
@@ -126,7 +126,7 @@
 
         <para>
             Class files (<filename>.bbclass</filename>) contain information that is useful to share
-            between metadata files. 
+            between metadata files.
             An example is the Autotools class, which contains
             common settings for any application that Autotools uses.
             The "<link linkend='ref-classes'>Classes</link>" chapter provides details
@@ -139,8 +139,8 @@
 
         <para>
             The configuration files (<filename>.conf</filename>) define various configuration variables
-            that govern the OpenEmbedded build process. 
-            These files fall into several areas that define machine configuration options, 
+            that govern the OpenEmbedded build process.
+            These files fall into several areas that define machine configuration options,
             distribution configuration options, compiler tuning options, general common configuration
             options and user configuration options (<filename>local.conf</filename>, which is found
             in the <ulink url='build-directory'>Build Directory</ulink>).
@@ -152,19 +152,19 @@
     <title>Shared State Cache</title>
 
     <para>
-        By design, the OpenEmbedded build system builds everything from scratch unless 
+        By design, the OpenEmbedded build system builds everything from scratch unless
         BitBake can determine that parts don't need to be rebuilt.
-        Fundamentally, building from scratch is attractive as it means all parts are 
-        built fresh and there is no possibility of stale data causing problems. 
+        Fundamentally, building from scratch is attractive as it means all parts are
+        built fresh and there is no possibility of stale data causing problems.
         When developers hit problems, they typically default back to building from scratch
         so they know the state of things from the start.
     </para>
 
-    <para>  
-        Building an image from scratch is both an advantage and a disadvantage to the process. 
-        As mentioned in the previous paragraph, building from scratch ensures that 
+    <para>
+        Building an image from scratch is both an advantage and a disadvantage to the process.
+        As mentioned in the previous paragraph, building from scratch ensures that
         everything is current and starts from a known state.
-        However, building from scratch also takes much longer as it generally means 
+        However, building from scratch also takes much longer as it generally means
         rebuilding things that don't necessarily need rebuilt.
     </para>
 
@@ -181,15 +181,15 @@
     </para>
 
     <para>
-        For the first question, the build system detects changes in the "inputs" to a given task by 
-        creating a checksum (or signature) of the task's inputs. 
-        If the checksum changes, the system assumes the inputs have changed and the task needs to be 
+        For the first question, the build system detects changes in the "inputs" to a given task by
+        creating a checksum (or signature) of the task's inputs.
+        If the checksum changes, the system assumes the inputs have changed and the task needs to be
         rerun.
         For the second question, the shared state (sstate) code tracks which tasks add which output
-        to the build process. 
+        to the build process.
         This means the output from a given task can be removed, upgraded or otherwise manipulated.
         The third question is partly addressed by the solution for the second question
-        assuming the build system can fetch the sstate objects from remote locations and 
+        assuming the build system can fetch the sstate objects from remote locations and
         install them if they are deemed to be valid.
     </para>
 
@@ -202,18 +202,18 @@
         <title>Overall Architecture</title>
 
         <para>
-            When determining what parts of the system need to be built, BitBake 
+            When determining what parts of the system need to be built, BitBake
             uses a per-task basis and does not use a per-recipe basis.
             You might wonder why using a per-task basis is preferred over a per-recipe basis.
-            To help explain, consider having the IPK packaging backend enabled and then switching to DEB. 
+            To help explain, consider having the IPK packaging backend enabled and then switching to DEB.
             In this case, <filename>do_install</filename> and <filename>do_package</filename>
             output are still valid.
-            However, with a per-recipe approach, the build would not include the 
-            <filename>.deb</filename> files.        
-            Consequently, you would have to invalidate the whole build and rerun it. 
+            However, with a per-recipe approach, the build would not include the
+            <filename>.deb</filename> files.
+            Consequently, you would have to invalidate the whole build and rerun it.
             Rerunning everything is not the best situation.
-            Also in this case, the core must be "taught" much about specific tasks. 
-            This methodology does not scale well and does not allow users to easily add new tasks 
+            Also in this case, the core must be "taught" much about specific tasks.
+            This methodology does not scale well and does not allow users to easily add new tasks
             in layers or as external recipes without touching the packaged-staging core.
         </para>
     </section>
@@ -222,37 +222,37 @@
         <title>Checksums (Signatures)</title>
 
         <para>
-            The shared state code uses a checksum, which is a unique signature of a task's 
-            inputs, to determine if a task needs to be run again. 
+            The shared state code uses a checksum, which is a unique signature of a task's
+            inputs, to determine if a task needs to be run again.
             Because it is a change in a task's inputs that triggers a rerun, the process
-            needs to detect all the inputs to a given task. 
+            needs to detect all the inputs to a given task.
             For shell tasks, this turns out to be fairly easy because
-            the build process generates a "run" shell script for each task and 
-            it is possible to create a checksum that gives you a good idea of when 
+            the build process generates a "run" shell script for each task and
+            it is possible to create a checksum that gives you a good idea of when
             the task's data changes.
         </para>
 
         <para>
-            To complicate the problem, there are things that should not be included in 
-            the checksum. 
-            First, there is the actual specific build path of a given task - 
-            the <filename>WORKDIR</filename>. 
-            It does not matter if the working directory changes because it should not 
+            To complicate the problem, there are things that should not be included in
+            the checksum.
+            First, there is the actual specific build path of a given task -
+            the <filename>WORKDIR</filename>.
+            It does not matter if the working directory changes because it should not
             affect the output for target packages.
-            Also, the build process has the objective of making native/cross packages relocatable. 
+            Also, the build process has the objective of making native/cross packages relocatable.
             The checksum therefore needs to exclude <filename>WORKDIR</filename>.
-            The simplistic approach for excluding the working directory is to set 
+            The simplistic approach for excluding the working directory is to set
             <filename>WORKDIR</filename> to some fixed value and create the checksum
-            for the "run" script. 
+            for the "run" script.
         </para>
 
         <para>
-            Another problem results from the "run" scripts containing functions that 
-            might or might not get called.  
-            The incremental build solution contains code that figures out dependencies 
+            Another problem results from the "run" scripts containing functions that
+            might or might not get called.
+            The incremental build solution contains code that figures out dependencies
             between shell functions.
-            This code is used to prune the "run" scripts down to the minimum set, 
-            thereby alleviating this problem and making the "run" scripts much more 
+            This code is used to prune the "run" scripts down to the minimum set,
+            thereby alleviating this problem and making the "run" scripts much more
             readable as a bonus.
         </para>
 
@@ -260,62 +260,62 @@
             So far we have solutions for shell scripts.
             What about python tasks?
             The same approach applies even though these tasks are more difficult.
-            The process needs to figure out what variables a python function accesses 
+            The process needs to figure out what variables a python function accesses
             and what functions it calls.
-            Again, the incremental build solution contains code that first figures out 
-            the variable and function dependencies, and then creates a checksum for the data 
+            Again, the incremental build solution contains code that first figures out
+            the variable and function dependencies, and then creates a checksum for the data
             used as the input to the task.
         </para>
 
         <para>
-            Like the <filename>WORKDIR</filename> case, situations exist where dependencies 
+            Like the <filename>WORKDIR</filename> case, situations exist where dependencies
             should be ignored.
             For these cases, you can instruct the build process to ignore a dependency
             by using a line like the following:
             <literallayout class='monospaced'>
      PACKAGE_ARCHS[vardepsexclude] = "MACHINE"
             </literallayout>
-            This example ensures that the <filename>PACKAGE_ARCHS</filename> variable does not 
+            This example ensures that the <filename>PACKAGE_ARCHS</filename> variable does not
             depend on the value of <filename>MACHINE</filename>, even if it does reference it.
         </para>
-           
+
         <para>
             Equally, there are cases where we need to add dependencies BitBake is not able to find.
             You can accomplish this by using a line like the following:
             <literallayout class='monospaced'>
       PACKAGE_ARCHS[vardeps] = "MACHINE"
             </literallayout>
-            This example explicitly adds the <filename>MACHINE</filename> variable as a 
+            This example explicitly adds the <filename>MACHINE</filename> variable as a
             dependency for <filename>PACKAGE_ARCHS</filename>.
         </para>
 
-        <para> 
+        <para>
             Consider a case with inline python, for example, where BitBake is not
-            able to figure out dependencies. 
-            When running in debug mode (i.e. using <filename>-DDD</filename>), BitBake 
+            able to figure out dependencies.
+            When running in debug mode (i.e. using <filename>-DDD</filename>), BitBake
             produces output when it discovers something for which it cannot figure out
-            dependencies. 
-            The Yocto Project team has currently not managed to cover those dependencies 
+            dependencies.
+            The Yocto Project team has currently not managed to cover those dependencies
             in detail and is aware of the need to fix this situation.
         </para>
 
         <para>
             Thus far, this section has limited discussion to the direct inputs into a task.
             Information based on direct inputs is referred to as the "basehash" in the
-            code. 
+            code.
             However, there is still the question of a task's indirect inputs - the
-            things that were already built and present in the Build Directory. 
-            The checksum (or signature) for a particular task needs to add the hashes 
-            of all the tasks on which the particular task depends. 
-            Choosing which dependencies to add is a policy decision. 
-            However, the effect is to generate a master checksum that combines the basehash 
+            things that were already built and present in the Build Directory.
+            The checksum (or signature) for a particular task needs to add the hashes
+            of all the tasks on which the particular task depends.
+            Choosing which dependencies to add is a policy decision.
+            However, the effect is to generate a master checksum that combines the basehash
             and the hashes of the task's dependencies.
         </para>
 
         <para>
             At the code level, there are a variety of ways both the basehash and the
-            dependent task hashes can be influenced. 
-            Within the BitBake configuration file, we can give BitBake some extra information 
+            dependent task hashes can be influenced.
+            Within the BitBake configuration file, we can give BitBake some extra information
             to help it construct the basehash.
             The following statements effectively result in a list of global variable
             dependency excludes - variables never included in any checksum:
@@ -325,42 +325,42 @@
   BB_HASHBASE_WHITELIST += "FILE_DIRNAME HOME LOGNAME SHELL TERM USER"
   BB_HASHBASE_WHITELIST += "FILESPATH USERNAME STAGING_DIR_HOST STAGING_DIR_TARGET"
             </literallayout>
-            The previous example actually excludes 
+            The previous example actually excludes
             <link linkend='var-WORKDIR'><filename>WORKDIR</filename></link>
-            since it is actually constructed as a path within 
-            <link linkend='var-TMPDIR'><filename>TMPDIR</filename></link>, which is on 
-            the whitelist. 
+            since it is actually constructed as a path within
+            <link linkend='var-TMPDIR'><filename>TMPDIR</filename></link>, which is on
+            the whitelist.
         </para>
 
         <para>
             The rules for deciding which hashes of dependent tasks to include through
-            dependency chains are more complex and are generally accomplished with a 
-            python function. 
+            dependency chains are more complex and are generally accomplished with a
+            python function.
             The code in <filename>meta/lib/oe/sstatesig.py</filename> shows two examples
-            of this and also illustrates how you can insert your own policy into the system 
+            of this and also illustrates how you can insert your own policy into the system
             if so desired.
             This file defines the two basic signature generators <filename>OE-Core</filename>
-            uses:  "OEBasic" and "OEBasicHash". 
-            By default, there is a dummy "noop" signature handler enabled in BitBake. 
-            This means that behavior is unchanged from previous versions. 
+            uses:  "OEBasic" and "OEBasicHash".
+            By default, there is a dummy "noop" signature handler enabled in BitBake.
+            This means that behavior is unchanged from previous versions.
             <filename>OE-Core</filename> uses the "OEBasic" signature handler by default
             through this setting in the <filename>bitbake.conf</filename> file:
             <literallayout class='monospaced'>
   BB_SIGNATURE_HANDLER ?= "OEBasic"
             </literallayout>
-            The "OEBasicHash" <filename>BB_SIGNATURE_HANDLER</filename> is the same as the 
-            "OEBasic" version but adds the task hash to the stamp files. 
-            This results in any metadata change that changes the task hash, automatically 
-            causing the task to be run again. 
+            The "OEBasicHash" <filename>BB_SIGNATURE_HANDLER</filename> is the same as the
+            "OEBasic" version but adds the task hash to the stamp files.
+            This results in any metadata change that changes the task hash, automatically
+            causing the task to be run again.
             This removes the need to bump <link linkend='var-PR'><filename>PR</filename></link>
-            values and changes to metadata automatically ripple across the build. 
+            values and changes to metadata automatically ripple across the build.
             Currently, this behavior is not the default behavior for <filename>OE-Core</filename>
             but is the default in <filename>poky</filename>.
         </para>
 
         <para>
             It is also worth noting that the end result of these signature generators is to
-            make some dependency and hash information available to the build. 
+            make some dependency and hash information available to the build.
             This information includes:
             <literallayout class='monospaced'>
   BB_BASEHASH_task-&lt;taskname&gt; - the base hashes for each task in the recipe
@@ -375,15 +375,15 @@
         <title>Shared State</title>
 
         <para>
-            Checksums and dependencies, as discussed in the previous section, solve half the 
+            Checksums and dependencies, as discussed in the previous section, solve half the
             problem.
             The other part of the problem is being able to use checksum information during the build
             and being able to reuse or rebuild specific components.
         </para>
 
         <para>
-            The shared state class (<filename>sstate.bbclass</filename>) 
-            is a relatively generic implementation of how to "capture" a snapshot of a given task. 
+            The shared state class (<filename>sstate.bbclass</filename>)
+            is a relatively generic implementation of how to "capture" a snapshot of a given task.
             The idea is that the build process does not care about the source of a task's output.
             Output could be freshly built or it could be downloaded and unpacked from
             somewhere - the build process doesn't need to worry about its source.
@@ -392,17 +392,17 @@
         <para>
             There are two types of output, one is just about creating a directory
             in <filename>WORKDIR</filename>.
-            A good example is the output of either <filename>do_install</filename> or 
-            <filename>do_package</filename>. 
-            The other type of output occurs when a set of data is merged into a shared directory 
+            A good example is the output of either <filename>do_install</filename> or
+            <filename>do_package</filename>.
+            The other type of output occurs when a set of data is merged into a shared directory
             tree such as the sysroot.
         </para>
 
         <para>
-            The Yocto Project team has tried to keep the details of the implementation hidden in 
-            <filename>sstate.bbclass</filename>. 
+            The Yocto Project team has tried to keep the details of the implementation hidden in
+            <filename>sstate.bbclass</filename>.
             From a user's perspective, adding shared state wrapping to a task
-            is as simple as this <filename>do_deploy</filename> example taken from 
+            is as simple as this <filename>do_deploy</filename> example taken from
             <filename>do_deploy.bbclass</filename>:
             <literallayout class='monospaced'>
      DEPLOYDIR = "${WORKDIR}/deploy-${PN}"
@@ -418,13 +418,13 @@
             </literallayout>
             In the example, we add some extra flags to the task, a name field ("deploy"), an
             input directory where the task sends data, and the output
-            directory where the data from the task should eventually be copied. 
+            directory where the data from the task should eventually be copied.
             We also add a <filename>_setscene</filename> variant of the task and add the task
             name to the <filename>SSTATETASKS</filename> list.
         </para>
 
         <para>
-            If you have a directory whose contents you need to preserve, you can do this with 
+            If you have a directory whose contents you need to preserve, you can do this with
             a line like the following:
             <literallayout class='monospaced'>
      do_package[sstate-plaindirs] = "${PKGD} ${PKGDEST}"
@@ -441,21 +441,21 @@
         </para>
 
         <para>
-            Behind the scenes, the shared state code works by looking in 
-            <link linkend='var-SSTATE_DIR'><filename>SSTATE_DIR</filename></link> and  
+            Behind the scenes, the shared state code works by looking in
+            <link linkend='var-SSTATE_DIR'><filename>SSTATE_DIR</filename></link> and
             <link linkend='var-SSTATE_MIRRORS'><filename>SSTATE_MIRRORS</filename></link>
-            for shared state files. 
+            for shared state files.
             Here is an example:
             <literallayout class='monospaced'>
      SSTATE_MIRRORS ?= "\
      file://.* http://someserver.tld/share/sstate/PATH \n \
      file://.* file:///some/local/dir/sstate/PATH"
             </literallayout>
-            <note> 
-                The shared state directory (<filename>SSTATE_DIR</filename>) is 
-                organized into two-character subdirectories, where the subdirectory 
+            <note>
+                The shared state directory (<filename>SSTATE_DIR</filename>) is
+                organized into two-character subdirectories, where the subdirectory
                 names are based on the first two characters of the hash.
-                If the shared state directory structure for a mirror has the 
+                If the shared state directory structure for a mirror has the
                 same structure as <filename>SSTATE_DIR</filename>, you must
                 specify "PATH" as part of the URI to enable the build system
                 to map to the appropriate subdirectory.
@@ -465,8 +465,8 @@
         <para>
             The shared state package validity can be detected just by looking at the
             filename since the filename contains the task checksum (or signature) as
-            described earlier in this section. 
-            If a valid shared state package is found, the build process downloads it 
+            described earlier in this section.
+            If a valid shared state package is found, the build process downloads it
             and uses it to accelerate the task.
         </para>
 
@@ -474,19 +474,19 @@
             The build processes uses the <filename>*_setscene</filename> tasks
             for the task acceleration phase.
             BitBake goes through this phase before the main execution code and tries
-            to accelerate any tasks for which it can find shared state packages. 
+            to accelerate any tasks for which it can find shared state packages.
             If a shared state package for a task is available, the shared state
             package is used.
-            This means the task and any tasks on which it is dependent are not 
+            This means the task and any tasks on which it is dependent are not
             executed.
         </para>
 
         <para>
             As a real world example, the aim is when building an IPK-based image,
-            only the <filename>do_package_write_ipk</filename> tasks would have their 
-            shared state packages fetched and extracted. 
-            Since the sysroot is not used, it would never get extracted. 
-            This is another reason why a task-based approach is preferred over a 
+            only the <filename>do_package_write_ipk</filename> tasks would have their
+            shared state packages fetched and extracted.
+            Since the sysroot is not used, it would never get extracted.
+            This is another reason why a task-based approach is preferred over a
             recipe-based approach, which would have to install the output from every task.
         </para>
     </section>
@@ -495,9 +495,9 @@
         <title>Tips and Tricks</title>
 
         <para>
-            The code in the build system that supports incremental builds is not 
+            The code in the build system that supports incremental builds is not
             simple code.
-            This section presents some tips and tricks that help you work around 
+            This section presents some tips and tricks that help you work around
             issues related to shared state code.
         </para>
 
@@ -505,25 +505,25 @@
             <title>Debugging</title>
 
             <para>
-                When things go wrong, debugging needs to be straightforward. 
+                When things go wrong, debugging needs to be straightforward.
                 Because of this, the Yocto Project team included strong debugging
                 tools:
                 <itemizedlist>
                     <listitem><para>Whenever a shared state package is written out, so is a
-                        corresponding <filename>.siginfo</filename> file. 
+                        corresponding <filename>.siginfo</filename> file.
                         This practice results in a pickled python database of all
                         the metadata that went into creating the hash for a given shared state
                         package.</para></listitem>
                     <listitem><para>If BitBake is run with the <filename>--dump-signatures</filename>
-                        (or <filename>-S</filename>) option, BitBake dumps out 
+                        (or <filename>-S</filename>) option, BitBake dumps out
                         <filename>.siginfo</filename> files in
                         the stamp directory for every task it would have executed instead of
                         building the specified target package.</para></listitem>
                     <listitem><para>There is a <filename>bitbake-diffsigs</filename> command that
-                        can process these <filename>.siginfo</filename> files. 
+                        can process these <filename>.siginfo</filename> files.
                         If one file is specified, it will dump out the dependency
-                        information in the file. 
-                        If two files are specified, it will compare the two files and dump out 
+                        information in the file.
+                        If two files are specified, it will compare the two files and dump out
                         the differences between the two.
                         This allows the question of "What changed between X and Y?" to be
                         answered easily.</para></listitem>
@@ -538,41 +538,41 @@
                 The shared state code uses checksums and shared state
                 cache to avoid unnecessarily rebuilding tasks.
                 As with all schemes, this one has some drawbacks.
-                It is possible that you could make implicit changes that are not factored 
-                into the checksum calculation, but do affect a task's output. 
+                It is possible that you could make implicit changes that are not factored
+                into the checksum calculation, but do affect a task's output.
                 A good example is perhaps when a tool changes its output.
                 Let's say that the output of <filename>rpmdeps</filename> needed to change.
                 The result of the change should be that all the "package", "package_write_rpm",
                 and "package_deploy-rpm" shared state cache items would become invalid.
                 But, because this is a change that is external to the code and therefore implicit,
                 the associated shared state cache items do not become invalidated.
-                In this case, the build process would use the cached items rather than running the 
-                task again. 
+                In this case, the build process would use the cached items rather than running the
+                task again.
                 Obviously, these types of implicit changes can cause problems.
             </para>
 
             <para>
                 To avoid these problems during the build, you need to understand the effects of any
                 change you make.
-                Note that any changes you make directly to a function automatically are factored into 
+                Note that any changes you make directly to a function automatically are factored into
                 the checksum calculation and thus, will invalidate the associated area of sstate cache.
-                You need to be aware of any implicit changes that are not obvious changes to the 
-                code and could affect the output of a given task. 
-                Once you are aware of such a change, you can take steps to invalidate the cache 
-                and force the task to run. 
-                The step to take is as simple as changing a function's comments in the source code. 
+                You need to be aware of any implicit changes that are not obvious changes to the
+                code and could affect the output of a given task.
+                Once you are aware of such a change, you can take steps to invalidate the cache
+                and force the task to run.
+                The step to take is as simple as changing a function's comments in the source code.
                 For example, to invalidate package shared state files, change the comment statements
                 of <filename>do_package</filename> or the comments of one of the functions it calls.
-                The change is purely cosmetic, but it causes the checksum to be recalculated and  
+                The change is purely cosmetic, but it causes the checksum to be recalculated and
                 forces the task to be run again.
             </para>
 
             <note>
-                For an example of a commit that makes a cosmetic change to invalidate 
+                For an example of a commit that makes a cosmetic change to invalidate
                 a shared state, see this
                 <ulink url='&YOCTO_GIT_URL;/cgit.cgi/poky/commit/meta/classes/package.bbclass?id=737f8bbb4f27b4837047cb9b4fbfe01dfde36d54'>commit</ulink>.
             </note>
-        </section>                
+        </section>
     </section>
 </section>
 
@@ -580,24 +580,24 @@
     <title>x32</title>
 
     <para>
-        x32 is a new processor-specific Application Binary Interface (psABI) for x86_64. 
-        An ABI defines the calling conventions between functions in a processing environment.  
+        x32 is a new processor-specific Application Binary Interface (psABI) for x86_64.
+        An ABI defines the calling conventions between functions in a processing environment.
         The interface determines what registers are used and what the sizes are for various C data types.
     </para>
 
     <para>
-        Some processing environments prefer using 32-bit applications even when running 
-        on Intel 64-bit platforms. 
+        Some processing environments prefer using 32-bit applications even when running
+        on Intel 64-bit platforms.
         Consider the i386 psABI, which is a very old 32-bit ABI for Intel 64-bit platforms.
         The i386 psABI does not provide efficient use and access of the Intel 64-bit processor resources,
-        leaving the system underutilized. 
+        leaving the system underutilized.
         Now consider the x86_64 psABI.
         This ABI is newer and uses 64-bits for data sizes and program pointers.
-        The extra bits increase the footprint size of the programs, libraries, 
+        The extra bits increase the footprint size of the programs, libraries,
         and also increases the memory and file system size requirements.
-        Executing under the x32 psABI enables user programs to utilize CPU and system resources 
+        Executing under the x32 psABI enables user programs to utilize CPU and system resources
         more efficiently while keeping the memory footprint of the applications low.
-        Extra bits are used for registers but not for addressing mechanisms. 
+        Extra bits are used for registers but not for addressing mechanisms.
     </para>
 
     <section id='support'>
@@ -608,14 +608,14 @@
             release supports current development specifications of x32 psABI.
             As of this release of the Yocto Project, x32 psABI support exists as follows:
             <itemizedlist>
-                <listitem><para>You can create packages and images in x32 psABI format on x86_64 architecture targets. 
+                <listitem><para>You can create packages and images in x32 psABI format on x86_64 architecture targets.
                     </para></listitem>
                 <listitem><para>You can use the x32 psABI support through the <filename>meta-x32</filename>
                     layer on top of the OE-core/Yocto layer.</para></listitem>
-                <listitem><para>The toolchain from the <filename>experimental/meta-x32</filename> layer 
+                <listitem><para>The toolchain from the <filename>experimental/meta-x32</filename> layer
                     is used for building x32 psABI program binaries.</para></listitem>
                 <listitem><para>You can successfully build many recipes with the x32 toolchain.</para></listitem>
-                <listitem><para>You can create and boot <filename>core-image-minimal</filename> and 
+                <listitem><para>You can create and boot <filename>core-image-minimal</filename> and
                     <filename>core-image-sato</filename> images.</para></listitem>
             </itemizedlist>
         </para>
@@ -625,18 +625,18 @@
         <title>Future Development and Limitations</title>
 
         <para>
-            As of this Yocto Project release, the x32 psABI kernel and library interfaces 
+            As of this Yocto Project release, the x32 psABI kernel and library interfaces
             specifications are not finalized.
         </para>
 
         <para>
             Future Plans for the x32 psABI in the Yocto Project include the following:
             <itemizedlist>
-                <listitem><para>Enhance and fix the few remaining recipes so they  
+                <listitem><para>Enhance and fix the few remaining recipes so they
                     work with and support x32 toolchains.</para></listitem>
                 <listitem><para>Enhance RPM Package Manager (RPM) support for x32 binaries.</para></listitem>
                 <listitem><para>Support larger images.</para></listitem>
-                <listitem><para>Integrate x32 recipes, toolchain, and kernel changes from 
+                <listitem><para>Integrate x32 recipes, toolchain, and kernel changes from
                     <filename>experimental/meta-x32</filename> into OE-core.</para></listitem>
             </itemizedlist>
         </para>
@@ -650,7 +650,7 @@
             Yocto Project, you can follow these steps to use the x32 spABI:
             <itemizedlist>
                 <listitem><para>Add the <filename>experimental/meta-x32</filename> layer to your local
-                    <ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>Build Directory</ulink>.  
+                    <ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>Build Directory</ulink>.
                     You can find the <filename>experimental/meta-x32</filename> source repository at
                     <ulink url='&YOCTO_GIT_URL;'></ulink>.</para></listitem>
                 <listitem><para>Edit your <filename>conf/bblayers.conf</filename> file so that it includes
@@ -677,8 +677,8 @@
          or 'INVALID'), True) or 'lib'}"
       #MACHINE = "atom-pc"
       #DEFAULTTUNE = "core2-64-x32"
-                    </literallayout></para></listitem> 
-                <listitem><para>As usual, use BitBake to build an image that supports the x32 psABI.  
+                    </literallayout></para></listitem>
+                <listitem><para>As usual, use BitBake to build an image that supports the x32 psABI.
                     Here is an example:
                     <literallayout class='monospaced'>
      $ bitake core-image-sato
@@ -696,15 +696,15 @@
     <title>Licenses</title>
 
     <para>
-        This section describes the mechanism by which the OpenEmbedded build system 
+        This section describes the mechanism by which the OpenEmbedded build system
         tracks changes to licensing text.
-        The section also describes how to enable commercially licensed recipes, 
+        The section also describes how to enable commercially licensed recipes,
         which by default are disabled.
     </para>
 
     <para>
-        For information that can help you maintain compliance with various open 
-        source licensing during the lifecycle of the product, see the 
+        For information that can help you maintain compliance with various open
+        source licensing during the lifecycle of the product, see the
         "<ulink url='&YOCTO_DOCS_DEV_URL;#maintaining-open-source-license-compliance-during-your-products-lifecycle'>Maintaining Open Source License Compliance During Your Project's Lifecycle</ulink>" section
         in the Yocto Project Development Manual.
     </para>
@@ -713,8 +713,8 @@
         <title>Tracking License Changes</title>
 
         <para>
-            The license of an upstream project might change in the future. 
-            In order to prevent these changes going unnoticed, the  
+            The license of an upstream project might change in the future.
+            In order to prevent these changes going unnoticed, the
             <filename><link linkend='var-LIC_FILES_CHKSUM'>LIC_FILES_CHKSUM</link></filename>
             variable tracks changes to the license text. The checksums are validated at the end of the
             configure step, and if the checksums do not match, the build will fail.
@@ -736,15 +736,15 @@
             </para>
 
             <para>
-                The build system uses the 
-                <filename><link linkend='var-S'>S</link></filename> variable as the 
-                default directory used when searching files listed in 
+                The build system uses the
+                <filename><link linkend='var-S'>S</link></filename> variable as the
+                default directory used when searching files listed in
                 <filename>LIC_FILES_CHKSUM</filename>.
                 The previous example employs the default directory.
             </para>
 
             <para>
-                You can also use relative paths as shown in the following example: 
+                You can also use relative paths as shown in the following example:
                 <literallayout class='monospaced'>
      LIC_FILES_CHKSUM = "file://src/ls.c;startline=5;endline=16;\
                                          md5=bb14ed3c4cda583abc85401304b5cd4e"
@@ -753,14 +753,14 @@
             </para>
 
             <para>
-                In this example, the first line locates a file in 
-                <filename>${S}/src/ls.c</filename>. 
-                The second line refers to a file in 
+                In this example, the first line locates a file in
+                <filename>${S}/src/ls.c</filename>.
+                The second line refers to a file in
                 <filename><link linkend='var-WORKDIR'>WORKDIR</link></filename>, which is the parent
                 of <filename><link linkend='var-S'>S</link></filename>.
             </para>
             <para>
-                Note that this variable is mandatory for all recipes, unless the 
+                Note that this variable is mandatory for all recipes, unless the
                 <filename>LICENSE</filename> variable is set to "CLOSED".
             </para>
         </section>
@@ -768,48 +768,48 @@
         <section id="usingpoky-LIC_FILES_CHKSUM-explanation-of-syntax">
             <title>Explanation of Syntax</title>
             <para>
-                As mentioned in the previous section, the 
-                <filename>LIC_FILES_CHKSUM</filename> variable lists all the 
-                important files that contain the license text for the source code. 
+                As mentioned in the previous section, the
+                <filename>LIC_FILES_CHKSUM</filename> variable lists all the
+                important files that contain the license text for the source code.
                 It is possible to specify a checksum for an entire file, or a specific section of a
                 file (specified by beginning and ending line numbers with the "beginline" and "endline"
-                parameters, respectively). 
+                parameters, respectively).
                 The latter is useful for source files with a license notice header,
                 README documents, and so forth.
-                If you do not use the "beginline" parameter, then it is assumed that the text begins on the 
-                first line of the file. 
-                Similarly, if you do not use the "endline" parameter, it is assumed that the license text 
-                ends with the last line of the file. 
+                If you do not use the "beginline" parameter, then it is assumed that the text begins on the
+                first line of the file.
+                Similarly, if you do not use the "endline" parameter, it is assumed that the license text
+                ends with the last line of the file.
             </para>
 
             <para>
-                The "md5" parameter stores the md5 checksum of the license text. 
+                The "md5" parameter stores the md5 checksum of the license text.
                 If the license text changes in any way as compared to this parameter
                 then a mismatch occurs.
                 This mismatch triggers a build failure and notifies the developer.
                 Notification allows the developer to review and address the license text changes.
-                Also note that if a mismatch occurs during the build, the correct md5 
+                Also note that if a mismatch occurs during the build, the correct md5
                 checksum is placed in the build log and can be easily copied to the recipe.
             </para>
 
             <para>
-                There is no limit to how many files you can specify using the 
+                There is no limit to how many files you can specify using the
                 <filename>LIC_FILES_CHKSUM</filename> variable.
-                Generally, however, every project requires a few specifications for license tracking. 
-                Many projects have a "COPYING" file that stores the license information for all the source 
+                Generally, however, every project requires a few specifications for license tracking.
+                Many projects have a "COPYING" file that stores the license information for all the source
                 code files.
-                This practice allows you to just track the "COPYING" file as long as it is kept up to date. 
+                This practice allows you to just track the "COPYING" file as long as it is kept up to date.
             </para>
 
             <tip>
-                If you specify an empty or invalid "md5" parameter, BitBake returns an md5 mis-match 
-                error and displays the correct "md5" parameter value during the build. 
-                The correct parameter is also captured in the build log. 
+                If you specify an empty or invalid "md5" parameter, BitBake returns an md5 mis-match
+                error and displays the correct "md5" parameter value during the build.
+                The correct parameter is also captured in the build log.
             </tip>
 
             <tip>
-                If the whole file contains only license text, you do not need to use the "beginline" and 
-                "endline" parameters. 
+                If the whole file contains only license text, you do not need to use the "beginline" and
+                "endline" parameters.
             </tip>
         </section>
     </section>
@@ -820,10 +820,10 @@
         <para>
             By default, the OpenEmbedded build system disables
             components that have commercial or other special licensing
-            requirements.  
+            requirements.
             Such requirements are defined on a
             recipe-by-recipe basis through the <filename>LICENSE_FLAGS</filename> variable
-            definition in the affected recipe.  
+            definition in the affected recipe.
             For instance, the
             <filename>$HOME/poky/meta/recipes-multimedia/gstreamer/gst-plugins-ugly</filename>
             recipe contains the following statement:
@@ -839,7 +839,7 @@
                 definition to be enabled and included in an image, it
                 needs to have a matching entry in the global
                 <filename>LICENSE_FLAGS_WHITELIST</filename> variable, which is a variable
-                typically defined in your <filename>local.conf</filename> file.  
+                typically defined in your <filename>local.conf</filename> file.
             For example, to enable
                 the <filename>$HOME/poky/meta/recipes-multimedia/gstreamer/gst-plugins-ugly</filename>
                 package, you could add either the string
@@ -867,7 +867,7 @@
                 the initial underscore character or characters.
             A partial string will match
                 any license that contains the given string as the first
-                portion of its license.  
+                portion of its license.
             For example, the following
                 whitelist string will also match both of the packages
                 previously mentioned as well as any other packages that have
@@ -879,7 +879,7 @@
 
         <section id="license-flag-matching">
             <title>License Flag Matching</title>
-       
+
             <para>
                         The definition of 'matching' in reference to a
                         recipe's <filename>LICENSE_FLAGS</filename> setting is simple.
@@ -891,7 +891,7 @@
                 Before a flag
                 defined by a particular recipe is tested against the
                 contents of the <filename>LICENSE_FLAGS_WHITELIST</filename> variable, the
-                string <filename>_${PN}</filename> (with 
+                string <filename>_${PN}</filename> (with
                 <link linkend='var-PN'><filename>PN</filename></link> expanded of course) is
                 appended to the flag, thus automatically making each
                 <filename>LICENSE_FLAGS</filename> value recipe-specific.
@@ -907,7 +907,7 @@
                 You can broaden the match by
                 putting any "_"-separated beginning subset of a
                 <filename>LICENSE_FLAGS</filename> flag in the whitelist, which will also
-                match.  
+                match.
                 For example, simply specifying "commercial" in
                 the whitelist would match any expanded <filename>LICENSE_FLAGS</filename>
                 definition starting with "commercial" such as
@@ -923,7 +923,7 @@
             <para>
                 Broadening the match allows for a range of specificity for the items
                 in the whitelist, from more general to perfectly
-                specific.  
+                specific.
                 So you have the choice of exhaustively
                 enumerating each license flag in the whitelist to
                 allow only those specific recipes into the image, or
@@ -935,7 +935,7 @@
             <para>
                 This scheme works even if the flag already
                 has <filename>_${PN}</filename> appended - the extra <filename>_${PN}</filename> is
-                redundant, but does not affect the outcome.  
+                redundant, but does not affect the outcome.
                 For example, a license flag of "commercial_1.2_foo" would
                 turn into "commercial_1.2_foo_foo" and would match
                 both the general "commercial" and the specific
@@ -944,8 +944,8 @@
                 "commercial_1.2_foo_foo" and "commercial_1.2", which
                 does not make much sense regarding use in the whitelist.
             </para>
-  
-            <para>  
+
+            <para>
                 For a versioned string, you could instead specify
                 "commercial_foo_1.2", which would turn into
                 "commercial_foo_1.2_foo".
@@ -993,8 +993,8 @@
             </para>
 
             <para>
-                Specifying audio and video plug-ins as part of the 
-                <filename>COMMERCIAL_AUDIO_PLUGINS</filename> and 
+                Specifying audio and video plug-ins as part of the
+                <filename>COMMERCIAL_AUDIO_PLUGINS</filename> and
                 <filename>COMMERCIAL_VIDEO_PLUGINS</filename> statements
                 or commercial qt components as part of
                 the <filename>COMMERCIAL_QT</filename> statement (along
@@ -1006,6 +1006,6 @@
     </section>
 </section>
 </chapter>
-<!-- 
-vim: expandtab tw=80 ts=4 
+<!--
+vim: expandtab tw=80 ts=4
 -->