Patching the kernel involves changing or adding configurations to an existing kernel, changing or adding recipes to the kernel that are needed to support specific hardware features, or even altering the source code itself.
yocto-kernel
script
found in the Source Directory
under scripts
to manage kernel patches and configuration.
See the "Managing kernel Patches and Config Items with yocto-kernel"
section in the Yocto Project Board Support Packages (BSP) Developer's Guide for
more information.
This example creates a simple patch by adding some QEMU emulator console
output at boot time through printk
statements in the kernel's
calibrate.c
source code file.
Applying the patch and booting the modified image causes the added
messages to appear on the emulator's console.
The example assumes a clean build exists for the qemux86
machine in a Source Directory named poky
.
Furthermore, the Build Directory is
build
and is located in poky
and
the kernel is based on the Linux 3.4 kernel.
For general information on how to configure the most efficient build, see the
"Building an Image" section
in the Yocto Project Quick Start.
Also, for more information on patching the kernel, see the "Applying Patches" section in the Yocto Project Linux Kernel Development Manual.