Questions about Kernel and kernel updates

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red-striped-zebra
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Questions about Kernel and kernel updates

Post by red-striped-zebra »

1. I received kernel updates for 5.4.0-149.166 two days ago. It doesn't show any changelog. Is that always the case with kernel updates?

2. Since kernel updates (represented by lightning) aren't security updates (represented by shield), is it necessary to update kernels every time? For instance I am currently running LM 20.3, and super happy with the performance. Do I still need to update the kernel, though these have nothing to do with security. Can't I just get the security updates and be done with it, or should I expect poor performance?

3. Is it okay to delete older kernel packages? I checked my installed kernels with this command

Code: Select all

dpkg --list | grep linux-image
I found the older packages are still there (from as old as 5.4.0-132.148 all the way to 5.4.0-148.165). I thought these were replaced automatically as the new ones install themselves. Is it wise and safe to remove them myself to free up space (because as it turns out, I never created separate partition for the kernel itself; but that's another thread)? If possible, I should like to remove all but the latest one.

4. What is the difference between an unsigned and signed kernel image? Internet answers not helping; need it more dumbed down.

So the same command above revealed kernel images from as old as 5.4.0-132.148 all the way to 5.4.0-148.165, and awkwardly, one version called 5.0.4-74.83. 74??? But that is so out of sequence, duh! Anyway all of them are signed.

BUT the last on the list is generic kernel image 5.4.0.148.146. Are generic kernels safe, and if they aren't safe (A youtuber made a comment saying signed are safer than unsigned/generic), why does linux install them on our machines?

Please enlighten me.

(edit: bold)
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Re: Questions about Kernel and kernel updates

Post by Pjotr »

The kernel changelogs are here:
http://changelogs.ubuntu.com/changelogs ... n/l/linux/

That's the best spot to query, because the Ubuntu kernels that Mint uses, get into Mint by means of a meta package which shows little or no changelog info in Update Manager.

No worries about signed or unsigned; that has to do with Secure Boot, which is a rather useless feature anyway (I recommend to disable it in the BIOS).

You can delete old unused kernels by means of the built-in kernel tool in Update Manager. Panel: View - Linux kernels. If you wish, you can freeze your kernel like this:
https://easylinuxtipsproject.blogspot.c ... 2.html#ID7
(item 7)

..... but in general, I don't recommend such a kernel freeze. Only for certain situations.
Last edited by Pjotr on Fri May 26, 2023 4:50 am, edited 1 time in total.
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Re: Questions about Kernel and kernel updates

Post by Boca »

red-striped-zebra wrote: Fri May 26, 2023 4:24 am ....
3. Is it okay to delete older kernel packages? I checked my installed kernels with this command

Code: Select all

dpkg --list | grep linux-image
....
Hi,

in update Manager - Edit - Preferences - Automation, you can select for obsolete/un-supported kernels to be removed.

Hope that helps.
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Re: Questions about Kernel and kernel updates

Post by Petermint »

Generally you keep at least one old kernel for a week or two while you use different applications. A kernel update might change something for graphics or WiFi or AMD that limits your use. You step back to the previous kernel then wait a month or two for a new kernel.

I never apply kernel updates when traveling without a full backup. The update may fail. Currently I am traveling but I have a full backup and a live Linux Mint on a bootable USB stick if I need to recover.
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Re: Questions about Kernel and kernel updates

Post by Termy »

red-striped-zebra wrote: Fri May 26, 2023 4:24 am Are generic kernels safe
I think what you really want to know is whether Canonical's generic kernels are unsafe.

I can analogise your question to asking whether a particular motorbike is safe. I'd say no motorbike is safe. There will always be dangers. Even on an empty road, a rock, pothole, or an oil spill in the wrong place might be enough to send you flying. Is any software truly safe? I brought this up to convey my view that it's not so much about being safe, but avoiding being unsafe. It's kind of a funny topic, really, because how could something that is already safe, be more safe? Surely, it's either safe or it isn't?

As I understand it, Canonical's generic kernels are basically kernels taken from kernel.org (the horse's mouth), but configured differently and maintained and revised separately by Canonical. I had faith in Canonical's generic kernels for years. Canonical have a good reputation to lose, they have a lot of experience, they have plenty of money to pay their developers, and they seem to have a good track record.

Essentially though, generic kernels are configured to work on as many people's systems as possible. The usual approach: suitable for everyone, optimal for nobody. But, this is why we have kernels specific to a given goal, such as security, performance, or low latency. The same applies to software and distributions. You could certainly argue that a hardened kernel is safer than Canonical's generic kernels, but that doesn't mean Canonical's generic kernels are unsafe.

Generic kernels are a good choice for most people.
red-striped-zebra wrote: Fri May 26, 2023 4:24 am Is it okay to delete older kernel packages?
It's OK to uninstall older kernels which you no longer need. As others have said, keeping around a 2nd kernel as a fallback is a sensible idea for most users.
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Re: Questions about Kernel and kernel updates

Post by Hoser Rob »

As long as the new kernel is with the same series ... in your case 5.4.etc ... I wouldn't worry about it so much. This is a valid concern, esp. with older hardware. You could always take a timeshift snapshot before, high level updates are kind of what it's for.

The reason is that kernel releases later that the 5.4 series are going to have some support features added for newer hardware but some support features for older hardware will be removed. The latter has really become more common with 5.x series kernels.
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Re: Questions about Kernel and kernel updates

Post by SMG »

red-striped-zebra wrote: Fri May 26, 2023 4:24 am2. Since kernel updates (represented by lightning) aren't security updates (represented by shield)
Kernel updates are represented by lightening because kernels are the core of the operating system and it is important to keep them updated. No other update gets the lightening; only kernels do. Kernels can and do include security updates as well as bug fixes and patches.
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Re: Questions about Kernel and kernel updates

Post by red-striped-zebra »

Thanks one and all for your valuable replies! Much appreciated.
Pjotr wrote: Fri May 26, 2023 4:43 am The kernel changelogs are here:
http://changelogs.ubuntu.com/changelogs ... n/l/linux/
Thanks for this. But why is this site NOT https? Didn't ubuntu get the memo?

Great answers, thanks.
No worries about signed or unsigned; that has to do with Secure Boot, which is a rather useless feature anyway (I recommend to disable it in the BIOS).
generic kernels are always unsigned, I assume.
Termy wrote: Fri May 26, 2023 4:43 am It's OK to uninstall older kernels which you no longer need. As others have said, keeping around a 2nd kernel as a fallback is a sensible idea for most users.
Thanks for your detailed explanation.

So, since the latest version is 5.4.0-149.166, I'll assume to 5.4.0-148.165 is the one I can use as fallback (?).
However, is there a way to find out which kernel version was supplied with the original .iso? I would like to keep that one as well.
SMG wrote: Fri May 26, 2023 4:43 am Kernel updates are represented by lightening because kernels are the core of the operating system and it is important to keep them updated. No other update gets the lightening; only kernels do. Kernels can and do include security updates as well as bug fixes and patches.
Ah, thanks for the correction.
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Re: Questions about Kernel and kernel updates

Post by red-striped-zebra »

One little thing I'd like someone to clarify:

using the dpkg --list | grep linux-image command shows the list of kernels. But at the bottom, where it likely has the latest kernel, it shows two kinds. For the latest kernel install in 20.3 LM cinnamon, it shows:

Code: Select all

5.4.0 DASH 149.166
AND

Code: Select all

5.4.0 DOT 149.147
As all the previous signed kernels are with DASH, I'll assume DASH is for signed, DOT is for generic. Am I right? And yet, at the time of update, System Manager informed 5.4.0 DASH 149.166 was the generic kernel it was going to install next. There was no mention of 5.4.0 DOT 149.147 being installed, yet it pops up the next day. So what are the last two segments in kernel version numbers?
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Re: Questions about Kernel and kernel updates

Post by SMG »

red-striped-zebra wrote: Sat May 27, 2023 8:12 am Thanks one and all for your valuable replies! Much appreciated.
Pjotr wrote: Fri May 26, 2023 4:43 am The kernel changelogs are here:
http://changelogs.ubuntu.com/changelogs ... n/l/linux/
Thanks for this. But why is this site NOT https? Didn't ubuntu get the memo?
The site is https. I just clicked the link and what came up is https://changelogs.ubuntu.com/changelog ... n/l/linux/
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Re: Questions about Kernel and kernel updates

Post by Termy »

red-striped-zebra wrote: Sat May 27, 2023 8:12 am So, since the latest version is 5.4.0-149.166, I'll assume to 5.4.0-148.165 is the one I can use as fallback (?).
However, is there a way to find out which kernel version was supplied with the original .iso? I would like to keep that one as well.
I'm not sure what the one just before 5.4.0-149.166 is. I'm not even familiar with that format, as, when I used generic kernels, they didn't have the extra .nnn on the end. The main thing is that the fallback kernel works, yet is still suitable. I would not keep around a kernel so old as the original that came with the ISO, but if you wanted to install it, it's probably in the repositories. I have no idea what the first one on any of the ISOs are. :lol:
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Re: Questions about Kernel and kernel updates

Post by TaterChip »

red-striped-zebra wrote: Sat May 27, 2023 8:12 am However, is there a way to find out which kernel version was supplied with the original .iso? I would like to keep that one as well.
This is what I was able to dig up
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Re: Questions about Kernel and kernel updates

Post by stevengarland »

Why are you sticking with old kernel 5.4? There are far newer approved kernels available. As SMG said new kernels are important.
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Re: Questions about Kernel and kernel updates

Post by TaterChip »

stevengarland wrote: Sat May 27, 2023 10:15 am Why are you sticking with old kernel 5.4? There are far newer approved kernels available. As SMG said new kernels are important.
I think mine is 5.15.something with the latest update of Mint. However isn't there a 6.something out there. IF so, why is Mint still on 5.15?
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Re: Questions about Kernel and kernel updates

Post by SMG »

red-striped-zebra wrote: Sat May 27, 2023 8:12 amHowever, is there a way to find out which kernel version was supplied with the original .iso? I would like to keep that one as well.
There is nothing special about the kernel used on the ISO. It's just what was the newest when the ISO was frozen and tested.
TaterChip wrote: Sat May 27, 2023 10:17 amI think mine is 5.15.something with the latest update of Mint. However isn't there a 6.something out there. IF so, why is Mint still on 5.15?
The 5.15 kernel is the newest one available for Linux Mint 20.3 which is what the OP is using.
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Re: Questions about Kernel and kernel updates

Post by TaterChip »

SMG wrote: Sat May 27, 2023 11:02 am The 5.15 kernel is the newest one available for Linux Mint 20.3 which is what the OP is using.
I was talking about in general. Why is the kernel in Mint so far behind what's available. Is it for stability reasons?
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Re: Questions about Kernel and kernel updates

Post by SMG »

TaterChip wrote: Sat May 27, 2023 11:06 amI was talking about in general. Why is the kernel in Mint so far behind what's available. Is it for stability reasons?
We ask people to not add new questions to someone else's topic like you are doing. The discussion of why Linux Mint is not using bleeding edge software is not part of this topic.

Short answer: Linux Mint uses Long-Term-Support kernels and tests the software against those kernels. If someone has newer hardware for which the kernel does not have the drivers, they can use a newer kernel series, but there is no guarantee it is known to work with the base operating system and components because it is not tested against them.

If you want more info, please create a new topic in the Chat about Linux Mint forum.
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Re: Questions about Kernel and kernel updates

Post by red-striped-zebra »

@SMG I take it Pjotr is an adventurous fellow.
stevengarland wrote: Sat May 27, 2023 10:15 am Why are you sticking with old kernel 5.4? There are far newer approved kernels available. As SMG said new kernels are important.
Because I am not a meddler (haven't enough knowledge!), so I accept what the Update Man brings me.

Also, because my LM 20.3 iso came with 5.4. I <3 LM 20.3's performance and have no intention to change it till the LTS retires. LM 21.1 is buggy, from what I keep reading here. Perhaps it takes upto xx.3 till the distro gets truly stable, I guess.
SMG wrote: Sat May 27, 2023 10:15 am The 5.15 kernel is the newest one available for Linux Mint 20.3 which is what the OP is using.
As per the Attachment posted by Taterchip, 5.1x kernel was for the EDGE version.

Logically, .1 series should be released before .4; so why confuse plebs, Torvalds?
There is nothing special about the kernel used on the ISO. It's just what was the newest when the ISO was frozen and tested.
In that case, I am keeping the latest and the penultimate one.
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Re: Questions about Kernel and kernel updates

Post by Pjotr »

red-striped-zebra wrote: Sat May 27, 2023 11:27 am @SMG I take it Pjotr is an adventurous fellow.
Not particularly, actually. In fact, I frequently prefer to err on the side of caution. Why would you think so?
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Re: Questions about Kernel and kernel updates

Post by red-striped-zebra »

Pjotr wrote: Sat May 27, 2023 3:14 pm Not particularly, actually. In fact, I frequently prefer to err on the side of caution. Why would you think so?
cause you posted an http(not secure) link to the ubuntu changelogs, in the second post.
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