diff --git a/documentation/kernel-dev/kernel-dev-common.xml b/documentation/kernel-dev/kernel-dev-common.xml
index f0e95aca07..6f39a70dff 100644
--- a/documentation/kernel-dev/kernel-dev-common.xml
+++ b/documentation/kernel-dev/kernel-dev-common.xml
@@ -148,16 +148,16 @@
You can make wholesale or incremental changes to the Linux
kernel .config file by including a
- defconfig or by specifying
- configuration fragments in the
+ defconfig and by specifying
+ configuration fragments in the
SRC_URI.
- If you have a complete Linux kernel .config
- file you want to use, copy it to a directory named
- files, which must be in
- your layer's recipes-kernel/linux
+ If you have a final Linux kernel .config
+ file you want to use, copy it to a directory named
+ files, which must be in
+ your layer's recipes-kernel/linux
directory, and name the file "defconfig".
Then, add the following lines to your linux-yocto
.bbappend file in your layer:
@@ -165,24 +165,36 @@
FILESEXTRAPATHS_prepend := "${THISDIR}/files:"
SRC_URI += "file://defconfig"
- The
- SRC_URI tells the build system how to
- search for the file, while the
+ The SRC_URI tells the build system how to
+ search for the file, while the
FILESEXTRAPATHS
- extends the
+ extends the
FILESPATH
- variable (search directories) to include the
+ variable (search directories) to include the
files directory you created for the
configuration changes.
+
+ The build system applies the configurations from the
+ .config file before applying any
+ subsequent configuration fragments.
+ The final kernel configuration is a combination of the
+ configurations in the .config file and
+ any configuration fragments you provide.
+ You need to realize that if you have any configuration
+ fragments, the build system applies these on top of and
+ after applying the existing .config
+ file configurations.
+
+
Generally speaking, the preferred approach is to determine the
incremental change you want to make and add that as a
configuration fragment.
For example, if you want to add support for a basic serial
- console, create a file named 8250.cfg in the
- files directory with the following
+ console, create a file named 8250.cfg in
+ the files directory with the following
content (without indentation):
CONFIG_SERIAL_8250=y
@@ -193,8 +205,8 @@
CONFIG_SERIAL_CORE=y
CONFIG_SERIAL_CORE_CONSOLE=y
- Next, include this configuration fragment and extend the
- FILESPATH variable in your
+ Next, include this configuration fragment and extend the
+ FILESPATH variable in your
.bbappend file:
FILESEXTRAPATHS_prepend := "${THISDIR}/files:"