[yocto] [PATCH v2 1/2] kernel-dev: Fix the locations of .config and source directory

[Tom Zanussi]

The locations of the kernel .config file and source directory moved a
couple releases ago; update the documentation accordingly.

Also, add a note explaining how to expand variables, which serves a
couple of purposes:

  * For curious readers, shows them how to demystify where these
    variables come from and how they're used.
  * For suspicious readers, shows them how they can verify that the
    variables in the documentation are actually correct.

Fixes [YOCTO #9124].

Signed-off-by: Tom Zanussi <tom.zanussi at linux.intel.com>
---
 documentation/kernel-dev/kernel-dev-common.xml | 20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/documentation/kernel-dev/kernel-dev-common.xml b/documentation/kernel-dev/kernel-dev-common.xml
index 261471c..5bd12be 100644
--- a/documentation/kernel-dev/kernel-dev-common.xml
+++ b/documentation/kernel-dev/kernel-dev-common.xml
@@ -384,9 +384,7 @@
 
             <para>
                 The resulting <filename>.config</filename> file is
-                located in
-                <filename>${</filename><ulink url='&YOCTO_DOCS_REF_URL;#var-WORKDIR'><filename>WORKDIR</filename></ulink><filename>}</filename> under the
-                <filename>linux-${</filename><ulink url='&YOCTO_DOCS_REF_URL;#var-PACKAGE_ARCH'><filename>PACKAGE_ARCH</filename></ulink><filename>}-${<ulink url='&YOCTO_DOCS_REF_URL;#var-LINUX_KERNEL_TYPE'><filename>LINUX_KERNEL_TYPE</filename></ulink>}-build</filename> directory.
+                located in the build directory,  <filename>${</filename><ulink url='&YOCTO_DOCS_REF_URL;#var-B'><filename>B</filename></ulink><filename>}</filename>, which expands to <filename>${</filename><ulink url='&YOCTO_DOCS_REF_URL;#var-WORKDIR'><filename>WORKDIR</filename></ulink><filename>}</filename><filename>/linux-</filename><filename>${</filename><ulink url='&YOCTO_DOCS_REF_URL;#var-PACKAGE_ARCH'><filename>PACKAGE_ARCH</filename></ulink><filename>}-${</filename><ulink url='&YOCTO_DOCS_REF_URL;#var-LINUX_KERNEL_TYPE'><filename>LINUX_KERNEL_TYPE</filename></ulink><filename>}-build</filename>.
                 You can use the entire <filename>.config</filename> file as the
                 <filename>defconfig</filename> file as described in the
                 "<link linkend='changing-the-configuration'>Changing the Configuration</link>" section.
@@ -396,6 +394,19 @@
                 section in the Yocto Project Development Manual.
             </para>
 
+            <note>
+              If you're ever confused about what a variable expands
+              to, you can determine that unequivocally by looking at
+              the output of the <filename>bitbake -e</filename> command:
+
+	      <literallayout class='monospaced'>
+     $ bitbake -e virtual/kernel
+              </literallayout>
+
+	      Search the output for the variable you're interested in
+	      and you can see exactly how it's expanded and used.
+            </note>
+
             <para>
                 A better method is to create a configuration fragment using the
                 differences between two configuration files: one previously
@@ -512,8 +523,7 @@
                 </literallayout>
                 Taking this step ensures you have the sources prepared
                 and the configuration completed.
-                You can find the sources in the
-                <filename>${</filename><ulink url='&YOCTO_DOCS_REF_URL;#var-WORKDIR'><filename>WORKDIR</filename></ulink><filename>}/linux</filename> directory.
+                You can find the sources in the symlinked <filename>source/</filename> directory just off the build directory, in other words <filename>${</filename><ulink url='&YOCTO_DOCS_REF_URL;#var-B'><filename>B</filename></ulink><filename>}/source</filename>, which expands to <filename>${</filename><ulink url='&YOCTO_DOCS_REF_URL;#var-WORKDIR'><filename>WORKDIR</filename></ulink><filename>}</filename><filename>/linux-</filename><filename>${</filename><ulink url='&YOCTO_DOCS_REF_URL;#var-PACKAGE_ARCH'><filename>PACKAGE_ARCH</filename></ulink><filename>}-${</filename><ulink url='&YOCTO_DOCS_REF_URL;#var-LINUX_KERNEL_TYPE'><filename>LINUX_KERNEL_TYPE</filename></ulink><filename>}-build/source</filename>.  The directory pointed to by the <filename>source/</filename> symlink is also known as <filename>${</filename><ulink url='&YOCTO_DOCS_REF_URL;#var-STAGING_KERNEL_DIR'><filename>STAGING_KERNEL_DIR</filename></ulink><filename>}</filename>
             </para>
 
             <para>
-- 
1.9.3