Has the Linux kernel 3.13.0-37 incorporated patch updating w/o rebooting?

[RLynwood]

Hello, all,

I'm still on 14.04, using kernel 3.13.0-37 and wondering, per the Subject, if I still need ksplice. I have it installed, but I don't have any reference to it: no entry in the K-menu or an icon in the system tray. If it isn't needed anymore, I can remove it; if it is needed for this kernel, I need to know how to get it displayed so as to have it working. I'll appreciate your help. Thanks.

Regards,
Ray

[Rod J]

Not sure how you are using such an old kernel. I'm using 3.13.0-55 now by the usual updates. Are you updating your system? Are you running a server (seems that is what ksplice is used for)?

[SteveRiley]

Ksplice is an older method for patching a running kernel without rebooting. It was acquired by Oracle who, alas, decided to keep the goods for their own Linux distro. Oracle offers a community version that integrates with something called Uptrack to download and apply patches.

Last year, kGraft (from SUSE) and Kpatch (from Red Hat) independently appeared. They use similar techniques, and a framework for both was incorporated into the kernel. If you truly need kernel hotpatching, these are the tools to look at. Ksplice is almost Oracle abandonware.

[Snowhog]

Oracle is still providing Ksplice for Ubuntu and Fedora Desktops for free.

http://ksplice.oracle.com/try/desktop

[SteveRiley]

Yep, that's the thing that uses Uptrack, a proprietary service from Oracle that takes care of the updating. Otherwise, you need to learn how to use the utilities to make your own diffs and keep kernel sources around.

kGraft and Kpatch are the future -- mainly because of the kernel integration and because these utilities are covered by open source licenses.

[RLynwood]

Thanks, all. Rod, my kernel is as old as it is because I'm using Mint 17.1 now. It's up to date--for it; I guess its kernel is just that old. I fully expect to update it to 17.2 as soon as its KDE version comes out.

I haven't installed Kubuntu 15.04 yet because of having gotten caught up in market concerns. I'll get to it as soon as I can, with my humble abilities.

Steve, your answer is what I was looking for. The only question I have is whether its been integrated into any kernel yet and, if so, which one. If it hasn't, how do I get Kpatch and make sure it's working? And if it isn't the right option for now, how do I get Ksplice Uptrack Manager working? As I said, its installed, but I doubt that it's working because I never get any notifications of kernel updates and there's no system tray icon for it.

[SteveRiley]

Steve, your answer is what I was looking for. The only question I have is whether its been integrated into any kernel yet and, if so, which one.

The foundations for supporting KPatch and kGraft are in kernel 4.0 and higher. LWN.net and other sources can provide more information -- searching for both terms will help.

If it hasn't, how do I get Kpatch and make sure it's working? And if it isn't the right option for now, how do I get Ksplice Uptrack Manager working? As I said, its installed, but I doubt that it's working because I never get any notifications of kernel updates and there's no system tray icon for it.

I don't know what the usability state of Kpatch and kGraft are -- your research should provide such information.

For Ksplice and regular kernel updates, you need to install ksplice-uptrack.deb from Oracle. Note: this is available only for Fedora and Ubuntu. It will surely work with Ubuntu flavors like Kubuntu; you'll need to test it yourself on Mint. According to the user's guide, this package includes a system tray notifier.

[RLynwood]

Thanks for the direction for Kgraft and kpatch. I'll pursue that.
And thanks for the direction for ksplice-uptrack. My problem was trusting the distro. I'd installed Ksplice via the repository, and it didn't install anything but the ksplice software itself. I've just installed Oracle's (free) version, and it installed completely, system-tray update icon and all (also, I checked SPM & the Software Manager, both of which verified what had been installed).

Do you use Ksplice, Kgraft, or Kpatch? And why?

[SteveRiley]

To properly use the version of Ksplice in the repository, you need to do what I mentioned in my post #5.

No, I don't use any of these technologies because I don't have farms of hundreds or thousands of servers to manage and keep running 100%. When new kernel updates appear, I install them and then reboot. At home I have one laptop and one server. A few seconds of downtime doesn't affect anyone.

[RLynwood]

To properly use the version of Ksplice in the repository, you need to do what I mentioned in my post #5.

I assume this statement refers to your statement

you need to learn how to use the utilities to make your own diffs and keep kernel sources around.

Right?

No, I don't use any of these technologies because I don't have farms of hundreds or thousands of servers to manage and keep running 100%. When new kernel updates appear, I install them and then reboot. At home I have one laptop and one server. A few seconds of downtime doesn't affect anyone.

I assume you're comparing the "few seconds" of rebooting time with the time it'd take to "use the utilities to make one's own diffs [what are these?] and keep the kernel sources around." Is that right? Otherwise, why bother rebooting if you don't have to?
I sure look forward to your future, when on of those foss kernel splicers is integrated into the kernel.

[SteveRiley]

I assume this statement refers to your statement
Right?

Correct.

I assume you're comparing the "few seconds" of rebooting time with the time it'd take to "use the utilities to make one's own diffs [what are these?] and keep the kernel sources around." Is that right?

A "diff" file contains only the differences between, say, file A and file B.

More on the Ksplice utilities: http://cormander.com/2011/08/how-to-...raw-utilities/
The person who wrote that is using Fedora. The instructions would be similar for Debian/Ubuntu, but the details on packaging would be different.

Otherwise, why bother rebooting if you don't have to?

There are other reasons that reboots are required besides kernel updates. Unless you're just interested in the mechanics of manipulating kernels, there's no advantage to using Ksplice on desktops. (Years ago I tried compiling my own kernels. I spent well over 50 hours learning all about various configuration options and trying to tweak everything as much as possible. There was absolutely no performance gain. So I went back to distro-supplied kernels.)

[RLynwood]

There are other reasons that reboots are required besides kernel updates.

Like what?

Unless you're just interested in the mechanics of manipulating kernels, there's no advantage to using Ksplice on desktops.

This certainly would be true if one had to do all that maintenance stuff you mentioned. I thought of it as simply not having to reboot, and no one, either in our LUG or in any forum, not that I've spent a lot of energy persuing it, ever has explained why Ksplice hasn't either been incorporated into the kernel--before Oracle bought it, though it was proprietary even then; I guess that's the reason--or commonly used by normal, everyday desktop users like me. It seemed to me like an obvious, no-brainer gain to the public, despite it's being proprietary, yet I saw almost no mention of it anywhere. And what very little comment I did see, seemed to be negative without saying why. So I appreciate your explanation. It's something I've wondered about for a long time--many years.

[SteveRiley]

Like what?

Changes to libc are best handled through rebooting. Some video driver updates work better when the machine is restarted, especially if the underlying kernel module is replaced. Applications that leak memory can render a machine into a state where a reboot is necessary. Sometimes you want to regularly test booting to ensure that the procedure continues to work.

This certainly would be true if one had to do all that maintenance stuff you mentioned. I thought of it as simply not having to reboot, and no one, either in our LUG or in any forum, not that I've spent a lot of energy persuing it, ever has explained why Ksplice hasn't either been incorporated into the kernel--before Oracle bought it, though it was proprietary even then; I guess that's the reason--or commonly used by normal, everyday desktop users like me.

For desktop users, there's no benefit to any of these technologies, really. With SSDs, your system can boot in a matter of seconds anyway.

It seemed to me like an obvious, no-brainer gain to the public, despite it's being proprietary, yet I saw almost no mention of it anywhere. And what very little comment I did see, seemed to be negative without saying why. So I appreciate your explanation. It's something I've wondered about for a long time--many years.

Ksplice works very well for systems that absolutely need 100% uptime. It kind of faded from view after Oracle bought it. But the need hasn't gone away -- that's why there's renewed interest in alternate approaches like Kpatch and kGraft.

[RLynwood]

Well, now I know some real, functional reasons for rebooting when required. Thanks. But, though I have an SSD, I'm not using it; I'm still using my multibooted, 5400rpm laptop drive. So rebooting takes more like a minute or more. As soon as I decide which OS I want to use from then on, Kubuntu or Mint, I'll install that on the SSD. Then it should reboot quickly.

"It kind of faded from view after Oracle bought it." That's what I thought I'd noticed and assumed that the foss community therefore had shown no interest in it.
"But the need hasn't gone away--that's why there's renewed interest in alternate approaches like Kpatch and kGraft." Well, despite your reasons for rebooting when required, I'm glad for at least this advancement. Now, if someones will develop a Debian version ....
Btw, I'm keeping a record of this entire conversation for future reference. I really appreciate your expertise and concise, cogent, articulate answers. I'll bet others do, too. Thanks.

P.s.
I installed Ksplice the other day, then ran all the updates it said were available, probably nearly 1-2 dozen. Then, after reading your post about why to reboot anyway, I removed ksplice. Since then the update manager has been giving an error message saying it can't connect with the server (my words, not theirs) each day when it checks for updates. But, when I click the close button, it then completes the update check, telling me if there is any update. From there it works fine.

[SteveRiley]

I installed Ksplice the other day, then ran all the updates it said were available, probably nearly 1-2 dozen. Then, after reading your post about why to reboot anyway, I removed ksplice. Since then the update manager has been giving an error message saying it can't connect with the server (my words, not theirs) each day when it checks for updates. But, when I click the close button, it then completes the update check, telling me if there is any update. From there it works fine.

Which update manager -- the Uptrack thing bundled with Oracle's Ksplice, or the standard Kubuntu/Muon update manager?