How to customize the Linux Kernel

From menuconfig

The most frequent way of customization of the Linux Kernel is to change the .config file that contains the Kernel options. Setup the environment and run:

pengwyn@pengwyn-desktop:~/yocto/build$ bitbake linux-pengwyn -c cleanall

...

pengwyn@pengwyn-desktop:~/yocto/build$ bitbake linux-pengwyn -c menuconfig

...

a new window, like the following one, will pop-up

follow the instructions, save and exit, than you ready to generate your preferred image based on your customized kernel. If you prefer, you can build just the kernel running:

pengwyn@pengwyn-desktop:~/yocto/build$ bitbake linux-pengwyn

...

At the end of the build process, the output file (uImage.bin), along with the built kernel modules (modules-3.2.0-r0-pengwyn.tgz), will be placed under tmp/deploy/images/ inside your build directory, so, if you are building your system from the default directory, the destination directory will be /home/pengwyn/yocto/build/tmp/deploy/images.

From sources

If you want to modify the Linux kernel sources instead, insert the following commands to create an image of the actual used sources:

pengwyn@pengwyn-desktop:~$ mkdir -p /home/pengwyn/Documents/linux-kernel
pengwyn@pengwyn-desktop:~$ cd /home/pengwyn/Documents/linux-kernel
pengwyn@pengwyn-desktop:~/Documents/linux-kernel$ cp /home/pengwyn/yocto/poky/meta-silica/recipes-kernel/linux/linux-pengwyn-3.2/linux-pengwyn* .
pengwyn@pengwyn-desktop:~/Documents/linux-kernel$ tar -xzf linux-pengwyn_3.2.tar.gz
pengwyn@pengwyn-desktop:~/Documents/linux-kernel$ mv linux-pengwyn_3.2 a
pengwyn@pengwyn-desktop:~/Documents/linux-kernel$ patch -p1 -d a/ < linux-pengwyn_3.2.patch
patching file ...
...
pengwyn@pengwyn-desktop:~/Documents/linux-kernel$ cp -r a/ b/

Modify the sources contained inside directory b, than create your patch

pengwyn@pengwyn-desktop:~/Documents/linux-kernel$ diff -Naur a/ b/ > linux-pengwyn_3.2.mine.patch
pengwyn@pengwyn-desktop:~/Documents/linux-kernel$ cp linux-pengwyn_3.2.mine.patch /home/pengwyn/yocto/poky/meta-silica/recipes-kernel/linux/linux-pengwyn-3.2/

Create a file named linux-pengwyn_3.2.bbappend inside directory /home/pengwyn/yocto/poky/meta-silica/recipes-kernel/linux/ and write the following text inside the .bbappend file:

SRC_URI += "file://linux-pengwyn_3.2.mine.patch \
"

Clean and build:

bitbake linux-pengwyn -c cleanall
bitbake linux-pengwyn