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How to update running kernel without reboot? I know about Oracle ksplice but it's not free and it supports only distributions that I don't use. Are there alternatives to ksplice?

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The underlying technology is free and part of the mainline kernel; Oracle just provides prebuilt images. You can build your own ksplice patches to dynamically load into your own kernel.

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That's nice! But where is it in menuconfig or how is it called in .config? – Alex Bolotov Feb 25 '12 at 14:38
See the ksplice package. – psusi Feb 25 '12 at 20:09
Hey, I've posted a follow-up on Ask Ubuntu that you might be able to answer (or help on): askubuntu.com/questions/193069/… – Oli Sep 26 '12 at 7:01
It might be nice to add more details to this answer instead of creating 2-sentence answers – ILMostro_7 Oct 22 '15 at 9:23

One alternative to ksplice is kexec(). Rather than patching the Linux kernel whilst running, this command essentially replaces the current kernel with a new one without rebooting your system.

In order for this to be available, it needs to be turned on as a compiler option in your distribution's kernel - that is, you can compile kernels without this functionality, so you'll need to check it is available and/or enable it yourself.

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Replacing the current kernel with a new one effectively is rebooting, just without the bother of going through the boot loader. You still end up having to save your work, shutdown, and restart your applications. – psusi Feb 25 '12 at 20:07

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