kernel-dev: Added 'make defconfig' details for own source work

I added some detail about what really happens when you use the
'make defconfig' command when working with your own sources.

Fixes [YOCTO #6611]

(From yocto-docs rev: 653c7726e024dcaa908127f0df1d1856f26f4ff0)

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

1 files changed, 12 insertions, 1 deletions

diff --git a/documentation/kernel-dev/kernel-dev-common.xml b/documentation/kernel-dev/kernel-dev-common.xml
index 532e2e87a6..27c82ceb58 100644
--- a/documentation/kernel-dev/kernel-dev-common.xml
+++ b/documentation/kernel-dev/kernel-dev-common.xml
@@ -646,7 +646,18 @@
                     <filename>files</filename> directory as "defconfig" and
                     then add it to the
                     <ulink url='&YOCTO_DOCS_REF_URL;#var-SRC_URI'><filename>SRC_URI</filename></ulink>
-                    variable in the recipe.
+                    variable in the recipe.</para>
+                    <para>Running the <filename>make defconfig</filename>
+                    command results in the default configuration for your
+                    architecture as defined by your kernel.
+                    However, no guarantee exists that this configuration is
+                    valid for your use case, or that your board will even boot.
+                    This is particularly true for non-x86 architectures.
+                    To use non-x86 <filename>defconfig</filename> files, you
+                    need to be more specific and find one that matches your
+                    board (i.e. for arm, you look in
+                    <filename>arch/arm/configs</filename> and use the one that
+                    is the best starting point for your board).
                     </para></listitem>
                 <listitem><para>Edit the following variables in your recipe
                     as appropriate for your project: