Anyway to change default kernel ("manjaro linux" of grub)? to other installed kernel?

Support
1

You know there is “manjaro linux” (which is like “default”) and “advance option for manjaro linux” (which we can choose which kernel we wants to boot up with )

The question is:
Is there way to change default boot up kernel if i have installed 3 kernels ?
I know that the 2 “default” in grub , “/etc/default/grub”
GRUB_DEFAULT=saved
GRUB_SAVEDEFAULT=true
will tell grub to remember my previous booted kernel.

But that doesn’t make “manjaro linux” (which is like “default” in grub menu) to become other kernel …
For example, i began by kernel : linux512
hence the “manjaro linux” in grub is pointing to linux512
how to make it pointing to other linux kernel that i have installed ? like 5.10 and 5.4 ?

Is it removing linux512 is the only way ? even though, after remove linux512, which kernel will take place of "manjaro linux " ?

Thanks

2

The other kernels are under submenu “advanced options” in grub’s boot menu

3

https://wiki.archlinux.org/title/GRUB/Tips_and_tricks#Changing_the_default_menu_entry

4

I know that. right now i have 3 kernels installed. 5.4, 5.10, 5.12 (EOL).
during boot up, i choose the grub option “manjaro linux” instead of advance, it boots up with 5.12.
But since 5.12 is out of support, i am lazy to remove it. i just want to change to 5.10 without needed to click into “advance menu” to select 5.10 every time boot up.

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5

But if you select the other kernel, that’s the one that is going to be booted the next time (because of the GRUB_DEFAULT=saved)

If you want to get rid of kernel 5.12, boot with 5.10, remove kernel 5.12 with sudo pacman -Rc linux512 and execute sudo update-grub (just in case, the remove of kernel 5.12 should already have triggered that). With this you can get that the “Manjaro Linux” entry is kernel 5.10

2 Likes
6

You mean if i have ( GRUB_DEFAULT=saved) , then when i booted with 5.10, then in the future (as long as i don’t select to boot up with other kernel) it will always auto start with 5.10 ?
I double confirmed it with you , because i think i did that, but it still boot up default with 5.12…

1 Like
7

Exactly

8

yap! exactly as i said. I just rebooted my laptop 3 times in a row… 1st time it booted up with 5.12 (when before i reboot it, it was 5.10).
then to be sure, i rebooted again… and choose “advance” > 5.10… booted up. and confirmed with uname -r
reboot again , at grub menu ; instead waiting 5 second time out, i just click on “manjaro linux” and it booted up. checked with uname -r, it is 5.12…

so, is it if i let it auto time out at grub it will boot up with my previous booted kernel … but when i click on “manjaro linux” (at grub menu) it will leads me to 5.12 ?? i have no idea…

9

yes, if we “click”, we select the last version (and not saved)
if we want “saved”(last kernel used) : not use keybord ! just wait

1 Like
10

i see… that’s why… as i have suspected.
When i heard other said "it will use last kernel, i thought “manjaro linux” at grub menu will point to previously booted kernel…

is there way to change " manjaro linux" to point to other kernel that i want instead of waiting till time out ?

11

No, there isn’t. But you can set a shorter timeout, so that you don’t have to wait that long. :stuck_out_tongue:

12

no : first line is always the last kernel
in default/grub

  • we can change key GRUB_TIMEOUT=2 (never set 0 ! after we can’t change kernel)
  • we can replace “saved” by one entry, example: GRUB_DEFAULT=2 for have always by default second entry (if we not use keyboard!) but is not really useful
1 Like
13

What do you meant by this 2 lines ?

So, if i uninstall kernel 5.12, which kernel will replace the grub menu "manjaro linux " ?
how is it decided which to replace “manjaro linux” of grub menu ? because i have got 5.4, 5.10 and 5.12 kernels installed

14

The “Manjaro Linux” entry in the GRUB menu will always point at the kernel with the highest version number.

Whichever kernel has the highest version number.

Please read the GRUB documentation for that information.

2 Likes
15

when we add/remove one kernel, manjaro run at last command update-grub, so line “manjaro linux” is for the last kernel version

for etc/default/grub, we have also : https://www.gnu.org/software/grub/manual/grub/html_node/Simple-configuration.html

2 Likes
16

I see… OK. understood now.

17

There is an easy way to see all your kernels on the first page, without these “manjaro linux” and “advanced options for manjaro”.

Just add the line GRUB_DISABLE_SUBMENU=true to /etc/default/grub and run sudo update-grub

1 Like
18

I was reading https://wiki.manjaro.org/index.php/Manjaro_Kernels
but this sentence puzzled me:

Otherwise, the following command will install a new kernel (3.13) to replace the existing kernel, **which will be deleted**:

sudo mhwd-kernel -i linux419 **rmc**

Why did author of this page said:
this command will install new kernel 3.13 to replace the currently run kernel, since the command stated linux419… why 3.13 ?
What does rmc in this cli means ? i can’t find rmc at all in

$ mhwd-kernel -h
Usage: mhwd-kernel [option]
-h --help Show this help message
-i --install Install a new kernel [kernel(s)] [optional: rmc = remove current kernel]
-l --list List all available kernels
-li --listinstalled List installed kernels
-r --remove Remove a kernel [kernel(s)]

1 Like
19

rmc means remove the current kernel. It tells you this just a few lines above the section you quoted.

The syntax of the command is as follows:

sudo mhwd-kernel [-i] [new kernel: linux(version)] [optional - remove the current kernel: rmc]

The other thing you mention looks like a typo.

20

hmm… i rebooted using kernel 510, used this cmd to remove kernel512…
sudo pacman -R linux512 linux512-headers linux512-extramodules
ran sudo update-grub (i think this cmd is not needed to run)
now i am booting in 510 even when i click on “manjaro linux”… however, my de is starting up slower… like i can actually feel it is slower… by maybe 1 or 2 seconds… as compare to before i remove 5.12 kernel.
However i did boot up with 510 kernel (before i remove 512 kernel), it never like this slow (even though 1 to 2 secs is not a big deal), just that is it something uninstalled not that flawlessly ? why slow at DE gui as compare to before uninstall kernel 512 ?