14 DAY TRIAL // A new development cycle has been started for the Linux kernel, 3.19, but it looks like the 3.20 branch is about to receive a very interesting patch that should really shake things up if it's going to get accepted, that is.
The OpenSuSE devs have been working for some time with a couple of tools called kPatch and kGraft. This essentially allows users to upgrade the Linux kernel on the fly without the need to restart the system. It might not seem like much for regular users with normal PCs, but please keep in mind that they represent only a small fraction of the total of Linux distros.
Servers powered by Linux are far more common and widespread and restarting a server is not exactly an option and it's usually done when it's something very important.
The ability to patch the kernel without the need to reboot is something that most other systems crave for, including the Windows and Mac OS X. There is no need to explain why this would be a great feature to have and why everyone is probably looking for ways to implement it.
openSUSE is already doing it
The openSUSE developers have been working on these tools for almost a year and they have been implemented in the latest openSUSE distribution. Like any of the major OSes out there, the devs don't use the stock kernel and they modify it according to their needs. In this case, they also have this patch already implemented. Now they are looking to push the patch into the Linux kernel, possibly for the 3.20 branch.
"A substantial amount of work has been invested into abstracing "Live Patching" core functionality out of the already existing implementations, so that further improvements can be built on top of it in incremental steps. The core functionality (which is self-contained) now works and has been Reviewed/Acked by both interested parties (i.e. people working on kPatch and kGraft) and agreed to be a common ground on which further development will happen."
"We plan to send a pull request for 3.20, therefore I'd like to ask you to include 'for-next' branch of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/livepatching.git into linux-next pile," wrote Jiri Kosina from SUSE Labs.
It's unclear whether the patch will be accepted into the 3.20 branch of the Linux kernel. This kind of feature might need some additional testing and it's quite a big deal. In any case, we'll have to wait for a couple of months or at least the 3.19 will be finished in order to see if it gets the approval of Linux Torvalds for the 3.20 devel cycle.
