Patches

Overview

Koble uses a patched Linux kernel to allow additional functionality and stability. An example of a kernel patch is the addition of random MAC addresses for network interfaces in a way that makes collisions unlikely. This is taken from Netkit.

Creating Patches

To create a patch you need two copies of the Linux kernel source. Use the URL defined by KERNEL_URL in BUILD to fetch the source code:

wget https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.14.9.tar.xz
tar -xvf linux-5.14.9.tar.xz
mv linux-source-5.14.9 linux-orig
cp -r linux-orig linux-custom

Now you can make changed to the source code within the linux-custom directory (while leaving linux-orig as it is).

To create a patch from the changes run:

diff -urpN linux-orig linux-custom > 93-tutorial-example.patch

Adding Patches to the Kernel Build

You can move the .patch file to the patches/ directory. The patch must also be added to the file patches/series, e.g:

patches/series

02_x-terminal-emulator.patch
03_uml_switch.patch
05_fix_static_build.patch
08-fix-pcap-linkage.patch
90-netkit_support.patch
93-tutorial-example.patch