[CONFIGURATION] upgrade kernerl or not to?

[lcharles]

I've read a few posts about adding back the ability for Kubuntu 18.04 to update the kernel. This post for example:

https://www.kubuntuforums.net/showth...Kunutu-18-04-2

what are the trade offs for keeping the kernel updated? It sounds like its a reasonable thing to do give the feature is added back in 18.04.2

[oshunluvr]

You may be a little confused or at least not using the correct terminology. The link you referenced is really about adding a higher (later) kernel line to the 18.04 LTS versions. It does indeed install a new kernel, but it's not about kernel updates as much as it is about newer hardware and X support, referred to as "HWE" aka "HardWare Enablement" . In other words, not installing the hwe packages doesn't mean your 4.15.0 kernel won't be updated - it will be up to 2023. It means that you'll move to the 4.18.0 kernel series and have support for newer hardware and maybe other changes. LTS releases by nature tend toward stability (in the Linux sense this means bug fixes rather than upgrades) and this includes the kernel.

Should you want to install this? Hard to say. If your PC is new-ish, probably yes. If it's ancient, probably no.

The real answer is: If you need support for something that exists in 4.18.0 but not in 4.15.0, yes install it. If you don't, you can anyway, but you may not see any difference. I know of no reason not to upgrade unless you find something stops working after installing it. Then just revert to 4.15.0.

I am maintaining 4 systems right now and am adding a 5th this week. I upgraded all of them to the newer HWE stack just so I would have consistency in configuration management. They're a mix of middle aged, new-ish, and new PCs. I've seen no problems.

My main point is, if you decide not the install the HWE packages, you'll still get kernel updates.

[lcharles]

yes, I have been confused. When I was using 16.04 the kernel was something like 4.10.0.25-generic. Periodically when I updated other packages it would be changed to something like 4.10.0.33-generic. I assumed these were kernel updates. With 18.04 I currently have 4.15.0.32-generic. Now once and a while when I do updates different kernels like 4.15.0.38 are downloaded but they are never installed. So I've been running 4.15.0.32-generic for a while and I've assumed the kernel is not being updated. Since I don't know if a hardware issue will come up some where down the line I'm inclined to install "HWE" and see how it goes. How this is all different than what happened with 16.04 I have no idea.

[claydoh]

It should not be any different than it has ever been for LTS releases. The current 4.15 kernel is .46, actually. if you saw a kernel being downloaded and did NOT install, you would have seen some sort of error message about packages failing to install.

My guess is that you for whatever reason are just booting to your .32 kernel, but have newer ones installed.

You can use Kinfocenter, or the command uname -r to check your current running kernel, and you can use Discover to look for all installed kernels by searching for installed packages containing the term linux-image-4.15, or (easier) use the command line:

apt search linux-image | grep installed

Why would you be "stuck" on the .32 kernel? One possibility is that if you for whatever reason booted to a different kernel in grub from the default one, that one becomes the new default. You can also check if you can select a different one in Grub (you should have at least two to choose from).


One cool thing to note that going to the HWE kernels does not remove the 4.15 kernels, it looks like you keep two version of the 4.18 and the 4.15, so there is a fallback for each one.

[lcharles]

Well something is odd.

uname -r
4.15.0-32-generic

apt search linux-image | grep installed

WARNING: apt does not have a stable CLI interface. Use with caution in scripts.

alsa-base/bionic,bionic,now 1.0.25+dfsg-0ubuntu5 all [installed]
linux-image-4.15.0-31-generic/now 4.15.0-31.33 amd64 [installed,local]
linux-image-4.15.0-32-generic/bionic-updates,bionic-security,now 4.15.0-32.35 amd64 [installed,automatic]

But when I use Muon to look at the list of available "linux-image-4.15" it shows everything from 4.15.0.31-generic to 4.15.0.46-generic but only .31 and .32 installed.
So if these were all downloaded and never installed, why? I don't want to force an install if something is not working right and break my system.
And I don't know if it's relevant (my lack of knowledge) but

sudo apt-get autoremove

gives

Reading package lists... Done
Building dependency tree       
Reading state information... Done
0 upgraded, 0 newly installed, 0 to remove and 3 not upgraded

[Snowhog]

That Muon Package Manager shows these kernels only means it knows about them. If not identified as installed, they aren’t installed.

[claydoh]

How are you performing updates?
Do an update in the terminal, and look at the output

sudo apt update
sudo apt full-upgrade

And see if any kernels are offered to be installed.

If not, try reinstalling the package linux-image-generic, which is a meta-package that depends on the current kernel, so will pull in the latest 4.15 kernel.

 sudo apt install --reinstall linux-image-generic

And see if that will pull in the current kernel.

[lcharles]

OK no kernels were offered to be installed.

l-k@l-k1804:~$ sudo apt install --reinstall linux-image-generic
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
linux-image-generic : Depends: linux-image-4.15.0-47-generic but it is not installable
                      Recommends: thermald but it is not going to be installed
E: Unable to correct problems, you have held broken packages.
l-k@l-k1804:~$

Also there was an update today that installed some packages but not the updated kernel. Here's installation output from that in case the output is useful. For updates I'm using:

sudo apt-get update && time sudo apt-get dist-upgrade

Anyway the output from the update is;

Reading package lists... Done
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Calculating upgrade... Done
The following packages were automatically installed and are no longer required:
 linux-headers-4.15.0-46 linux-headers-4.15.0-46-generic
Use 'sudo apt autoremove' to remove them.
The following NEW packages will be installed:
 linux-headers-4.15.0-47 linux-headers-4.15.0-47-generic
The following packages will be upgraded:
 apt apt-utils libapt-inst2.0 libapt-pkg5.0 libnss-systemd libpam-systemd libsystemd0 libsystemd0:i386
 libudev1 libudev1:i386 linux-headers-generic linux-libc-dev opera-stable systemd systemd-sysv udev
16 upgraded, 2 newly installed, 0 to remove and 0 not upgraded.
Need to get 0 B/90.7 MB of archives.
After this operation, 90.1 MB of additional disk space will be used.
Do you want to continue? [Y/n] y
Preconfiguring packages ...
(Reading database ... 288176 files and directories currently installed.)
Preparing to unpack .../libsystemd0_237-3ubuntu10.16_i386.deb ...
De-configuring libsystemd0:amd64 (237-3ubuntu10.15) ...
Unpacking libsystemd0:i386 (237-3ubuntu10.16) over (237-3ubuntu10.15) ...
Preparing to unpack .../libsystemd0_237-3ubuntu10.16_amd64.deb ...
Unpacking libsystemd0:amd64 (237-3ubuntu10.16) over (237-3ubuntu10.15) ...
Setting up libsystemd0:amd64 (237-3ubuntu10.16) ...
Setting up libsystemd0:i386 (237-3ubuntu10.16) ...
(Reading database ... 288176 files and directories currently installed.)
Preparing to unpack .../0-libnss-systemd_237-3ubuntu10.16_amd64.deb ...
Unpacking libnss-systemd:amd64 (237-3ubuntu10.16) over (237-3ubuntu10.15) ...
Preparing to unpack .../1-libpam-systemd_237-3ubuntu10.16_amd64.deb ...
Unpacking libpam-systemd:amd64 (237-3ubuntu10.16) over (237-3ubuntu10.15) ...
Preparing to unpack .../2-systemd_237-3ubuntu10.16_amd64.deb ...
Unpacking systemd (237-3ubuntu10.16) over (237-3ubuntu10.15) ...
Preparing to unpack .../3-udev_237-3ubuntu10.16_amd64.deb ...
Unpacking udev (237-3ubuntu10.16) over (237-3ubuntu10.15) ...
Preparing to unpack .../4-libudev1_237-3ubuntu10.16_amd64.deb ...
De-configuring libudev1:i386 (237-3ubuntu10.15) ...
Unpacking libudev1:amd64 (237-3ubuntu10.16) over (237-3ubuntu10.15) ...
Preparing to unpack .../5-libudev1_237-3ubuntu10.16_i386.deb ...
Unpacking libudev1:i386 (237-3ubuntu10.16) over (237-3ubuntu10.15) ...
Setting up systemd (237-3ubuntu10.16) ...
(Reading database ... 288176 files and directories currently installed.)
Preparing to unpack .../systemd-sysv_237-3ubuntu10.16_amd64.deb ...
Unpacking systemd-sysv (237-3ubuntu10.16) over (237-3ubuntu10.15) ...
Preparing to unpack .../libapt-pkg5.0_1.6.10_amd64.deb ...
Unpacking libapt-pkg5.0:amd64 (1.6.10) over (1.6.9) ...
Setting up libudev1:amd64 (237-3ubuntu10.16) ...
Setting up libudev1:i386 (237-3ubuntu10.16) ...
Setting up libapt-pkg5.0:amd64 (1.6.10) ...
(Reading database ... 288176 files and directories currently installed.)
Preparing to unpack .../libapt-inst2.0_1.6.10_amd64.deb ...
Unpacking libapt-inst2.0:amd64 (1.6.10) over (1.6.9) ...
Preparing to unpack .../archives/apt_1.6.10_amd64.deb ...
Unpacking apt (1.6.10) over (1.6.9) ...
Setting up apt (1.6.10) ...
(Reading database ...

288177 files and directories currently installed.)
Preparing to unpack .../0-apt-utils_1.6.10_amd64.deb ...
Unpacking apt-utils (1.6.10) over (1.6.9) ...
Preparing to unpack .../1-opera-stable_58.0.3135.107_amd64.deb ...
Unpacking opera-stable (58.0.3135.107) over (58.0.3135.90) ...
Selecting previously unselected package linux-headers-4.15.0-47.
Preparing to unpack .../2-linux-headers-4.15.0-47_4.15.0-47.50_all.deb ...
Unpacking linux-headers-4.15.0-47 (4.15.0-47.50) ...
Selecting previously unselected package linux-headers-4.15.0-47-generic.
Preparing to unpack .../3-linux-headers-4.15.0-47-generic_4.15.0-47.50_amd64.deb ...
Unpacking linux-headers-4.15.0-47-generic (4.15.0-47.50) ...
Preparing to unpack .../4-linux-headers-generic_4.15.0.47.49_amd64.deb ...
Unpacking linux-headers-generic (4.15.0.47.49) over (4.15.0.46.48) ...
Preparing to unpack .../5-linux-libc-dev_4.15.0-47.50_amd64.deb ...
Unpacking linux-libc-dev:amd64 (4.15.0-47.50) over (4.15.0-46.49) ...
Setting up libapt-inst2.0:amd64 (1.6.10) ...
Setting up libnss-systemd:amd64 (237-3ubuntu10.16) ...
Setting up linux-headers-4.15.0-47 (4.15.0-47.50) ...
Processing triggers for mime-support (3.60ubuntu1) ...
Processing triggers for ureadahead (0.100.0-20) ...
ureadahead will be reprofiled on next reboot
Processing triggers for desktop-file-utils (0.23-1ubuntu3.18.04.2) ...
Setting up apt-utils (1.6.10) ...
Setting up systemd-sysv (237-3ubuntu10.16) ...
Setting up linux-libc-dev:amd64 (4.15.0-47.50) ...
Processing triggers for menu (2.1.47ubuntu2.1) ...
Setting up opera-stable (58.0.3135.107) ...
Setting up linux-headers-4.15.0-47-generic (4.15.0-47.50) ...
Processing triggers for libc-bin (2.27-3ubuntu1) ...
Setting up udev (237-3ubuntu10.16) ...
update-initramfs: deferring update (trigger activated)
Processing triggers for man-db (2.8.3-2ubuntu0.1) ...
Processing triggers for shared-mime-info (1.9-2) ...
Unknown media type in type 'all/all'
Unknown media type in type 'all/allfiles'
Processing triggers for dbus (1.12.2-1ubuntu1) ...
Processing triggers for hicolor-icon-theme (0.17-2) ...
Setting up linux-headers-generic (4.15.0.47.49) ...
Setting up libpam-systemd:amd64 (237-3ubuntu10.16) ...
Processing triggers for menu (2.1.47ubuntu2.1) ...
Processing triggers for initramfs-tools (0.130ubuntu3.7) ...
update-initramfs: Generating /boot/initrd.img-4.15.0-32-generic

[lcharles]

I hope I didn't post too much information. Is there something I should try next?

[jglen490]

When was the last time you rebooted after an upgrade?

I ask because while a new kernel may be referenced in grub, that new kernel won't be put into use until you reboot.

This may not be the actual solution to your problem, but it is a possibility.

[claydoh]

Also, if you've ever selected a different kernel in Grub, that one will become the default one that boots automatically, I think.

[lcharles]

I reboot after each update or upgrade. Looking at the kernels available with Muon shows .47-generic available but not installed. In fact Muon only shows .31-generic and ..32-generic installed.

[claydoh]

The following packages have unmet dependencies:
linux-image-generic : Depends: linux-image-4.15.0-47-generic but it is not installable

oops missed this one. This is the reason why you don't have the current kernel automatically. You could manually install the linux-image-4-15.0-47 package for the latest one, of course, but you'd still have to do this every time a new one is made, and hope you notice when this happens, so we need to find out why the meta-package linux-image-generic won't install