openSUSE:Online Kernel Patching

Requirements

SLE11 SP2 or some latest openSUSE release
Installed Ksplice package from OBS
Some kernel patch (a diff) you want to apply online

Building a Binary Patch

Step 1: Build a SUSE kernel

This should result in two directories:

linux-<version> with sources, and
linux-obj with object files

Step 2: Creating Configuration for Ksplice

Configuration is meant to be a directory where Ksplice reads from. It should contain these three entries:

build: a link to linux-obj above
flags: a text file with flags passed to make. This is usually "O=<path to linux-obj>"
System.map: simply a copy of build/System.map

Step 3: Creating Binary Patch

The final step is to actually create the binary patch. Now, it is as simple as running ksplice-create:

ksplice-create --patch=<path_to_diff> --config=<path_to_conf_dir> <path_to_linux_sources>

Note that it accepts also -j parameter to perform a parallel build and speed up the whole process.

Patching the Kernel

Given the binary patch, you can just call ksplice-apply utility to apply the patch as follows:

ksplice-apply ksplice-<id>.tar.gz

And check what patches are applied:

ksplice-view

Unpatching the Kernel

Sometimes you might want to remove patches from the running system. For that purpose, ksplice-undo exists. The only thing needed is the id of the patch. You can find that by ksplice-view. Then issue command like the one below to get rid of the patch.

ksplice-undo ksplice-<id>