Linux kernel no reboot

How can I upgrade my server’s kernel without rebooting?

This is a loaded question because I’m already aware of, and am very interested in ksplice. The problem is that since they were bought by Oracle, they have been forced to pull numerous server distributions from the offerings. The answer isn’t as simple as it once was. I noticed a question on Unix.SE that states:

Great! But how?!

I’ve installed the free ksplice package in the repo on my desktop (not ksplice-uptrack which is non-free) and now want to generate and apply updates. What’s the process? Are there any scripts out there to automate the process? Moreover, if all the machinery required for rebootless upgrades is sitting there in the kernel (and ksplice package), why on earth aren’t we taking advantage of it by default? Quite recently kGraft was announced. It seems to be roughly the same result so if you have an answer that involves it, I’d be just as happy with that. It’s currently a few months from being released though. Note 1: I am happy for a solution beside ksplice but it has to deliver the same thing: rolling updates to the kernel that can be applied without rebooting the server. Note 2: I’ll say it again; the main ksplice «service» does not support Ubuntu Server. It used to but it doesn’t any more. When I talk about wanting to use ksplice, I’m talking about the open source tools in the ksplice package. Any answer that talks about ksplice-uptrack is probably not what I’m after as this is the part that integrates directly with aforementioned «service».

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ubuntu upgrade kernel without reboot

There is no way to use the updated kernel without restarting your system. Until you restart, you will still be using the old kernel you booted into when you started up your computer prior to updating your kernel.

Do I need to reboot after kernel update?

With versions of Linux before 4.0, when the kernel is updated via a patch, the system needs to reboot. . This is why it’s important to install the patch as soon as possible. Unlike other operating systems, Linux is able to update many different parts of the system without a reboot, but the kernel is different.

How does Linux update without reboot?

Live kernel patching is the process of applying security patches to a running Linux kernel without the need for a system reboot. The implementation for Linux is named livepatch. The process of patching a live kernel is a fairly complex process. It can be compared to an open heart surgery.

How do I change the kernel parameters in Linux without rebooting?

1. Read variable from command line. Type the following command. .
2. Write variable from command line. The syntax is: .
3. Reload settings from all system configuration files. Type the following command to reload settings from config files without rebooting the box: .
4. Persistent configuration.

How do I upgrade my kernel?

1. Step 1: Check Your Current Kernel Version. At a terminal window, type: uname –sr. .
2. Step 2: Update the Repositories. At a terminal, type: sudo apt-get update. .
3. Step 3: Run the upgrade. While still in the terminal, type: sudo apt-get dist-upgrade.

What is Ubuntu Live patch?

Livepatch allows you to install some critical kernel security updates without rebooting your system, by directly patching the running kernel. . It’s mainly intended for servers which are supposed to have months and years of continuous uptime without reboots.

What is a kernel patch?

Kernel patch may refer to: . Ksplice, an extension of the Linux kernel that allows security patches to be applied to a running kernel. XNU kernel patch, a series of initial patches necessary to run the OSx86 kernel on non-Apple hardware.

Does Linux need to be rebooted?

Linux servers never need to be rebooted unless you absolutely need to change the running kernel version. Most problems can be solved by changing a configuration file and restarting a service with an init script. . I usually reboot after scheduled system updates, though.

How does Ubuntu Livepatch work?

The Canonical Livepatch Service removes all of the aggravation of keeping your Ubuntu systems up to date with critical kernel patches. . You must be using a Long Term Support (LTS) release of Ubuntu such as 16.04 or 18.04. The most recent LTS version is 18.04, so that’s the version we’re going to use here.

How do I permanently change kernel parameters in Linux?

To permanently modify kernel parameters, either use the sysctl command to write the values to the /etc/sysctl. conf file or make manual changes to the configuration files in the /etc/sysctl. d/ directory.

What are the kernel parameters in Linux?

The kernel parameter sem consists of 4 tokens, SEMMSL, SEMMNS, SEMOPM and SEMMNI. SEMMNS is the result of SEMMSL multiplied by SEMMNI. The database manager requires that the number of arrays (SEMMNI) be increased as necessary.

What is kernel tuning in Linux?

Linux System V Shared Memory Kernel Tuning

SHMMNI — This parameter sets the system wide maximum number of shared memory segments. It should be set to at least the number of nodes that are to be run on the system using System V Shared Memory.

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How Linux servers update their kernel without rebooting

According to my informations, upgrading the linux kernel needs a reboot. Rebooting a home computer is not a problem, but I don’t think that it is the same thing for a server. So does the servers that use Linux distributions reboot after upgrading the kernel, or do they use some kind of a trick to avoid booting ??

2 Answers 2

Yes, they do a «reboot», but could do a kexec_load system call to preload the new kernel.

There is the possibility of patching the running kernel as well, redhat kpatch for example. All the things which do this that I am aware of can not change the data structures.

Of course lisp machines used to be able to patch their running kernels in the last century.

There’s also vanilla kexec , for just booting the new kernel immediately. Depending on your definition of «reboot», this might qualify as a non-reboot kernel upgrade.

A kernel change should get a reboot. You can install the kernel, and in some cases you can insert and remove modules of different kernels, but I would not advise it.

A server could be rebooted and service would be unaffected if the server is part of a cluster. You can create firewall/router clusters too, such that there is no single point of failure (SPOF). To do this you use what is called a Virtual IP (VIP) that is shared across more than one system.

If you want to experiment with this idea you can use QEMU or VirtualBox and others to create virtual networks.

The question was not specific to minor patching but mentions ‘upgrade’ which I will take to mean major version upgrades. Therefore, to ‘upgrade’ from 2.6 -> 3.0 I would recommend dropping the machine from load before starting upgrade work. Post kernel changes I would reboot. Since grub/lilo is likely to need changes I would suggest a courtesy reboot anyway.

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