Hi There,
I have been patching the kernel in my Alma 8.8 OS and it has installed an Alma 8.10 kernel ‘4.18.0-553.159.1.el8_10.x86_64’
If I reboot my host, will it use this latest kernel and is it safe to use the higher OS kernel in a lower version?
Regards,
Mohammad Farhan
You can see the default kernel by running:
grubby --info DEFAULT
It is usually safe to boot a newer kernel, but it might depend on what patching you did.
Yeah! My Alma 8.8 host shows that it booted from 8.10 kernel → kernel-4.18.0-553.159.1.el8_10.x86_64
Is it OK? No compatibility issues due to lower OS version?
Is it recommended OR I need to upgrade my OS to 8.10 as well?
You really should update your system fully to address bugs (security and otherwise). There is no reason to cherry pick updates like you did here, especially with the kernel. To reduce security issues, to reduce potential compatibility problems, and to reduce potential unforeseen system issues, I (and many others) would recommend that you fully update your system.
Just to reinforce what has been said with an example, I recently had an SSHD failure (locking everyone out) on a host than had not been patched since EL9.2. Installation of a new package resulted in OpenSSL being upgraded to an EL9.8 version which was incompatible with the EL9.2 SSHD. In principle, there could be package metadata that would have told DNF to also upgrade SSHD, but it probably either didn’t occur to the packagers, or they left it out to keep the metadata more efficient, because nobody’s supposed to be doing mixing packages like that.
With me it’s generally the reverse: I’ll run an older kernel with newer userspace because I’m missing a compatible version of an out-of-tree kernel module. A lot of the time you can get away with it, especially when the gap is small, but in general, the further you deviate from latest-latest-latest, the more likely you are to run into problems, because nobody’s out there anticipating and testing all the possible combinations of package versions and making sure they work. It just wouldn’t be feasible.
The 8.10 kernel may work on AlmaLinux 8.8, but mixing packages from different minor releases is not recommended.
A similar issue occurred on AlmaLinux 9.2, where OpenSSH failed because it was built against a different OpenSSL version than the one installed at runtime.
It is safer to update the whole system to AlmaLinux 8.10.