I am using webmin (which uses yum) to install updates on my server, and it somestimes updates kernel as well including kernel-firmware and kernel-headers. Do I need to restart the server after a kernel update?
There are at least two reasons for rebooting:
- You probably want to use the advantages of the newer version (security fixes)
- Usually during a kernel update the module tree of the old kernel is removed. Thus if you (or some script) unload a module then the system cannot load it again because it finds only the newer one on disk (if at all) and this is compiled for a different kernel and thus cannot be loaded (at least usually).
To actually use the new kernel you will have to reboot.
No way around that.
Do you have to reboot immediately after installing the update ?
In general NOT, you can schedule the reboot for a more convenient moment.
But it is NOT a good idea to install more updates before you reboot.
Some updates have different versions depending on which kernel you are running.
And anyway: After rebooting with a new kernel always check for updates. Some of your existing packages may need a new version after the kernel update.
With Linux 4.0 and later, they say you don't have to reboot for the Kernel anymore.