is it safe to have only one kernel installed

Loyalty_Cham · 2018-10-04 18:21:00

Hello community.
Sorry if it's a bit silly question, but I was wondering whether if it's safe to have only one kernel installed on your Arch system.
I do here people saying that it's advisable to have both LTS and latest kernel installed. But I do like to have only the latest kernel installed in my system.

Is there any harm or disadvantage of having only the latest kernel installed.

Thanks! Your help are much appreciated.

ugjka · 2018-10-04 18:29:22

keep an install iso handy on some usb stick in case kittens die after an update

jasonwryan · 2018-10-04 18:29:35

Yes, it is "safe". The advantage of another kernel is that if one fails to boot, the other one may still come up. You could keep a USB with the ISO on it for the same purpose.

Slithery · 2018-10-04 18:30:57

The only disadvantage is it takes slightly longer to fix if the new kernel doesn't work with your system - You'll need to boot from an Arch install USB to fix it rather than just selecting a different kernel from your bootloader.

qinohe · 2018-10-04 21:08:12

Hi, yes good idea, you can install as many as you like, I don't think there is a maximum.
Right now I have a problem with certain kernels, The safeguard was a different kernel, otherwise you would need the ISO, which you can load with certain bootloaders too btw.

Trilby · 2018-10-04 21:53:06

As noted above, having a second kernel installed can help solve some problems easier than needing a bootable medium (e.g., usb) around. But what hasn't yet been noted is that the set of problems that could be solved this way are pretty small.

There are all sorts of problems that could hinder your normal workflow, but you'd still be able to boot (at least into multi-user or rescue targets) and fix the problem with no bootable usb required. There are also various problems that could prevent booting entirely, regardless of the kernel used, and in these cases you would need a bootable usb whether or not you had a second kernel installed. Then there are pretty small number of problems that would prevent you from booting your default kernel (even with the fallback initramfs) but might allow you to still boot a different spare kernel.

But given the fact that you probably want a bootable usb around anyways to deal with any problems that require it, having a second kernel really doesn't do anything for you other than saving a couple of seconds in working through an extremely unlikely problem.

That really doesn't seem worth it to me.

There can be reasons to have a second kernel installed including testing different kernel patchsets, or using different patch sets for different tasks, but keeping a spare around to deal with booting issues just doesn't make sense as a reason to me.

HiImTye · 2018-10-04 23:33:16

keep in mind that if you use DKMS, your update time will be cumulatively larger for every kernel and every DKMS package, for the small advantage of not having to boot from a USB stick occasionally.

ngoonee · 2018-10-05 01:10:15

HiImTye wrote:

keep in mind that if you use DKMS, your update time will be cumulatively larger for every kernel and every DKMS package, for the small advantage of not having to boot from a USB stick occasionally.

This was the reason I ended up not using 'backup' kernels. USB sticks are everywhere, and I keep old-ish bootable Arch on every USB I own just in case (doesn't take much space).

Lupo Alberto · 2018-10-05 08:32:56

It's best for me to have some rescue live-cd as *.iso file in /boot and set by propriate way grub.cfg.

Last edited by Lupo Alberto (2018-10-05 08:35:28)

Loyalty_Cham · 2018-10-05 09:38:41

Thanks a lot guys for the positive comments. I have a usb and I will put Arch there just incase if any thing goes wrong

c00ter · 2018-10-05 14:22:41

My machine gets a little *finicky* when new current kernels are introduced but always seems to work well with the LTS kernel so, for me & this machine, keeping more than one kernel installed is very handy.

regards

Trilby · 2018-10-05 14:48:05

c00ter, if that's the case why not just stick with LTS?

c00ter · 2018-10-06 01:24:52

Trilby wrote:

c00ter, if that's the case why not just stick with LTS?

When this laptop was new in mid-2014 only the current kernel worked. Common on new hardware, I know, as well as the LTS kernel catching up with the then new hardware a couple of months later. Since then I keep the LTS for a little bit better audio/video streaming response, and the current kernel for a security blanket just in case the next LTS upgrade goes south. That has never happened in the near-4 years now that the LTS has been resident on this computer, but still...

A valid question, Trilby.

Last edited by c00ter (2018-10-06 01:26:15)

ngoonee · 2018-10-06 03:04:56

Trilby wrote:

c00ter, if that's the case why not just stick with LTS?

If his machine survives long enough (highly likely, nowadays) it'll eventually be the LTS kernels which make his computer finicky.

graysky · 2018-10-06 06:56:50

Lupo Alberto wrote:

It's best for me to have some rescue live-cd as *.iso file in /boot and set by propriate way grub.cfg.

Agreed. I do the same (iso on SSD with entry in grub.cfg):

cat /etc/grub.d/40_custom
...

menuentry 'ISO loopback-Arch (on SSD)' {
set reldate=2018.10.01
###
set isofile="archlinux-$reldate-x86_64.iso"
set imgdevpath='/dev/sdb1'
loopback loop (hd2,1)/$isofile
linux (loop)/arch/boot/x86_64/vmlinuz img_dev=$imgdevpath img_loop=$isofile archisobasedir=arch earlymodules=loop
initrd (loop)/arch/boot/x86_64/archiso.img
}

...

ngoonee wrote:

Trilby wrote:
c00ter, if that's the case why not just stick with LTS?
If his machine survives long enough (highly likely, nowadays) it'll eventually be the LTS kernels which make his computer finicky.

Depends... if whatever is causing the problem eventually get fixed, that fix could be backported to LTS.

c00ter · 2018-10-06 16:33:06

ngoonee wrote:

Trilby wrote:
c00ter, if that's the case why not just stick with LTS?
If his machine survives long enough (highly likely, nowadays) it'll eventually be the LTS kernels which make his computer finicky.

Good to know, ngoonee, since my wife and I have been known to use even a older, busted-screen laptop as a file server.

regards

ngoonee · 2018-10-07 20:45:09

graysky wrote:

ngoonee wrote:
Trilby wrote:
c00ter, if that's the case why not just stick with LTS?
If his machine survives long enough (highly likely, nowadays) it'll eventually be the LTS kernels which make his computer finicky.
Depends... if whatever is causing the problem eventually get fixed, that fix could be backported to LTS.

The civic-conscious part of me says that that will only happen if he stays on mainline AND reports whatever finicky issues exist. The practical part of me says someone else will do that, so yes LTS would possibly have it fixed. For various definitions of 'it'.

frank604 · 2018-10-07 21:59:42

@graysky
I never thought to place the iso and create an entry. Brilliant! That saves me 1 usb stick lol and convenience of not having to look for this 1 stick in a box of many. cool beans yo.

Trilby · 2018-10-07 22:06:19

The iso makes even less sense to me than the extra kernel. Problems that would require the iso (e.g., the default/fallback kernels not able to boot) yet still allow the iso to boot (e.g., not a bootloader issue) is an incredibly narrow wedge of the pie of possible problems.

If you want a fallback plan for worst-case scenarios, you should really have a fallback plan that will *actually work* under worst-case scenarios.

Having an iso in your bootloader makes about as much sense to me as health insurance that only covers you as long as you are healthy (a scam that is perpetrated by many insurance companies today).

frank604 · 2018-10-07 22:21:17

Excellent point Trilby.

Back to the OP's question. Few years ago, I used to carry multiple bootable iso from my phone via DriveDroid. https://softwarebakery.com/projects/drivedroid **does require root though**

Last edited by frank604 (2018-10-07 22:22:20)

jasonwryan · 2018-10-07 22:30:04

Remember the days when Arch would fail to boot? Good times...

Loyalty_Cham · 2018-10-07 23:19:22

Arch never failed me

Trilby · 2018-10-08 00:54:16

forum sidebar wrote:

Loyalty_Cham
Member
Registered: 2018-06-18

That's why. You don't remember those days; you weren't here for them

ngoonee · 2018-10-08 09:21:09

Trilby wrote:

Having an iso in your bootloader makes about as much sense to me as health insurance that only covers you as long as you are healthy (a scam that is perpetrated by many insurance companies today).

*must* *resist* *bikeshed*

Trilby wrote:

forum sidebar wrote:
Loyalty_Cham
Member
Registered: 2018-06-18
That's why. You don't remember those days; you weren't here for them

Or he's admitting to using a dupe account? Tbf I've been around for quite a bit and I don't ever remember Arch failing to boot (well except for PEBKAC-type errors like a wrong dd or targetting the wrong partition for some command or other).

Trilby · 2018-10-08 13:57:07

ngoonee wrote:

Tbf I've been around for quite a bit and I don't ever remember Arch failing to boot (well except for PEBKAC-type errors like a wrong dd or targetting the wrong partition for some command or other).

All errors are PEBKAC errors. But it seems there were previously more frequent conditions that resulted in large numbers of users showing a PEBKAC pattern. I remember a bash upgrade that required manual intervention 5 years ago or so that led to a fair share of problems.

Arch Linux

#1 2018-10-04 18:21:00

is it safe to have only one kernel installed

#2 2018-10-04 18:29:22

Re: is it safe to have only one kernel installed

#3 2018-10-04 18:29:35

Re: is it safe to have only one kernel installed

#4 2018-10-04 18:30:57

Re: is it safe to have only one kernel installed

#5 2018-10-04 21:08:12

Re: is it safe to have only one kernel installed

#6 2018-10-04 21:53:06

Re: is it safe to have only one kernel installed

#7 2018-10-04 23:33:16

Re: is it safe to have only one kernel installed

#8 2018-10-05 01:10:15

Re: is it safe to have only one kernel installed

#9 2018-10-05 08:32:56

Re: is it safe to have only one kernel installed

#10 2018-10-05 09:38:41

Re: is it safe to have only one kernel installed

#11 2018-10-05 14:22:41

Re: is it safe to have only one kernel installed

#12 2018-10-05 14:48:05

Re: is it safe to have only one kernel installed

#13 2018-10-06 01:24:52

Re: is it safe to have only one kernel installed

#14 2018-10-06 03:04:56

Re: is it safe to have only one kernel installed

#15 2018-10-06 06:56:50

Re: is it safe to have only one kernel installed

#16 2018-10-06 16:33:06

Re: is it safe to have only one kernel installed

#17 2018-10-07 20:45:09

Re: is it safe to have only one kernel installed

#18 2018-10-07 21:59:42

Re: is it safe to have only one kernel installed

#19 2018-10-07 22:06:19

Re: is it safe to have only one kernel installed

#20 2018-10-07 22:21:17

Re: is it safe to have only one kernel installed

#21 2018-10-07 22:30:04

Re: is it safe to have only one kernel installed

#22 2018-10-07 23:19:22

Re: is it safe to have only one kernel installed

#23 2018-10-08 00:54:16

Re: is it safe to have only one kernel installed

#24 2018-10-08 09:21:09

Re: is it safe to have only one kernel installed

#25 2018-10-08 13:57:07

Re: is it safe to have only one kernel installed

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