Grub: how to remember the last boot choice?

[Fred_VIE]

Hello,

I have Manjaro on SDC1, cachy-os on SDB1 and win10 (which I do not really boot into anymore) on SDA1 and would like grub to remember the last OS that I have booted into. Searching for it I have found this command that was supposed to make grub remember the last boot choice:

sudo grub-set-default saved 

Unfortunately it does still not remember the last OS that I have been booting up.

My /etc/default/grub/

# GRUB boot loader configuration

GRUB_DEFAULT=saved
GRUB_TIMEOUT=5
GRUB_DISTRIBUTOR='Manjaro'
GRUB_CMDLINE_LINUX_DEFAULT='quiet splash udev.log_priority=3'
GRUB_CMDLINE_LINUX=""

# Preload both GPT and MBR modules so that they are not missed
GRUB_PRELOAD_MODULES="part_gpt part_msdos"

# Uncomment to enable booting from LUKS encrypted devices
#GRUB_ENABLE_CRYPTODISK=y

# Set to 'countdown' or 'menu' to change timeout behavior,
# press ESC key to display menu.
GRUB_TIMEOUT_STYLE=hidden

# Uncomment to use basic console
GRUB_TERMINAL_INPUT=console

# Uncomment to disable graphical terminal
#GRUB_TERMINAL_OUTPUT=console

# The resolution used on graphical terminal
# note that you can use only modes which your graphic card supports via VBE
# you can see them in real GRUB with the command 'videoinfo'
GRUB_GFXMODE=auto

# Uncomment to allow the kernel use the same resolution used by grub
GRUB_GFXPAYLOAD_LINUX=keep

# Uncomment if you want GRUB to pass to the Linux kernel the old parameter
# format "root=/dev/xxx" instead of "root=/dev/disk/by-uuid/xxx"
#GRUB_DISABLE_LINUX_UUID=true

# Uncomment to disable generation of recovery mode menu entries
GRUB_DISABLE_RECOVERY=false

# Uncomment and set to the desired menu colors.  Used by normal and wallpaper
# modes only.  Entries specified as foreground/background.
GRUB_COLOR_NORMAL="light-gray/black"
GRUB_COLOR_HIGHLIGHT="green/black"

# Uncomment one of them for the gfx desired, a image background or a gfxtheme
#GRUB_BACKGROUND="/usr/share/grub/background.png"
GRUB_THEME="/usr/share/grub/themes/manjaro/theme.txt"

# Uncomment to get a beep at GRUB start
#GRUB_INIT_TUNE="480 440 1"

# Uncomment to make GRUB remember the last selection. This requires
# setting 'GRUB_DEFAULT=saved' above.
GRUB_SAVEDEFAULT=false

# Uncomment to disable submenus in boot menu
#GRUB_DISABLE_SUBMENU=y

# Uncomment this option to enable os-prober execution in the grub-mkconfig command
#GRUB_DISABLE_OS_PROBER=false

# Uncomment to ensure that the root filesystem is mounted read-only so that
# systemd-fsck can run the check automatically. We use 'fsck' by default, which
# needs 'rw' as boot parameter, to avoid delay in boot-time. 'fsck' needs to be
# removed from 'mkinitcpio.conf' to make 'systemd-fsck' work.
# See also Arch-Wiki: https://wiki.archlinux.org/index.php/Fsck#Boot_time_checking
#GRUB_ROOT_FS_RO=true
GRUB_DISABLE_OS_PROBER=false

I have added the other OS’ to the boot menu this way:

echo GRUB_DISABLE_OS_PROBER=false | sudo tee -a /etc/default/grub && sudo update-grub

Thanks

[Arrababiski]

@Fred_VIE

# Uncomment to make GRUB remember the last selection. This requires
# setting 'GRUB_DEFAULT=saved' above.
GRUB_SAVEDEFAULT=false

Have you tried to set this to true?

[Aragorn]

@Fred_VIE

Searching for it I have found this command that was supposed to make grub remember the last boot choice:

sudo grub-set-default saved 

Unfortunately it does still not remember the last OS that I have been booting up.

If /boot is on btrfs — which is the default in Manjaro as of the 25.0 Zetar release — then this will indeed not work anymore, because grub cannot write to btrfs.

The only way to render grub capable of remembering the last-booted entry — as it used to be in the past — would be to either use ext4 for the root filesystem or have a separate ext4 partition of about 1 GiB for /boot, and to then set the proper options in /etc/default/grub.

[Fred_VIE]

@Aragorn

The only way to render grub capable of remembering the last-booted entry — as it used to be in the past — would be to either use ext4 for the root filesystem or have a separate ext4 partition of about 1 GiB for /boot, and to then set the proper options in /etc/default/grub

Damn. I have an nvme drive with ext4 though. How can I install the bootmanager on that one?

I have always installed the bootmanager on the OS-drive because I was scared to install it on one central drive for all OS’. Now it seems I have no other choice anymore, because both Manjaro and Cachy are on BTRFS just the game libraries remain on EXT4. Although there is a script they say can be used on Cachy that could address that. I have never used scripts though.

[Aragorn]

@Fred_VIE

@Aragorn

The only way to render grub capable of remembering the last-booted entry — as it used to be in the past — would be to either use ext4 for the root filesystem or have a separate ext4 partition of about 1 GiB for /boot, and to then set the proper options in /etc/default/grub

Damn. I have an nvme drive with ext4 though. Could I use that one?

I think you misunderstand. If the system boots in UEFI mode, then it’ll load the grub EFI stub — essentially an EFI executable — from /boot/efi. This stub will then in turn load its configuration from /boot.

If you have the option enabled to save the last-booted entry, then grub — note: the operating system is not loaded yet at that point — will attempt to save this boot entry to the filesystem that /boot is on, because grub mounts this filesystem by itself as its own root.

In a default installation, /boot is part of the root filesystem, which as of Manjaro 25.0 is btrfs. But grub cannot write to btrfs — in some cases it even already has difficulty reading from it.

In other words, you’ve got three options…:

1. Reinstall Manjaro and pick ext4 for your root filesystem;

2. Reinstall Manjaro and pick btrfs for your root filesystem, but also create a dedicated ext4 partition of 1 GiB, to be mounted at /boot; or…

3. Find an empty ext4 partition of 1 GiB, temporarily mount it at /mnt, move over the contents of your /boot to /mnt, unmount /mnt and mount that same partition at /boot — you could use a “mount --move” to do the whole thing in one go — and edit your /etc/fstab to include a record for /boot.

[Fred_VIE]

@Aragorn

Find an empty ext4 partition of 1 GiB, temporarily mount it at /mnt, move over the contents of your /boot to /mnt, unmount /mnt and mount that same partition at /boot — you could use a “mount --move” to do the whole thing in one go — and edit your /etc/fstab to include a record for /boot.

It must be an empty 1 GB ext4 partition and cannot just be put on the nvme?

So basically if I had told it to install the bootmanager on the nvme it would have failed because of a missing 1 gb ext4 or would it have worked?

@Aragorn

Reinstall Manjaro

not again….

@Arrababiski

@Fred_VIE

GRUB_SAVEDEFAULT=false

Have you tried to set this to true?

yea, is being ignored

[Aragorn]

@Fred_VIE

@Aragorn

Find an empty ext4 partition of 1 GiB, temporarily mount it at /mnt, move over the contents of your /boot to /mnt, unmount /mnt and mount that same partition at /boot — you could use a “mount --move” to do the whole thing in one go — and edit your /etc/fstab to include a record for /boot.

It must be an empty 1 GB ext4 partition and cannot just be put on the nvme?

It should be a dedicated partition, and I am advising 1 GiB because if you’re going to be storing a couple of kernels and their initramfs — both main and fallback — then you’ll quickly end up filling up that space.

@Fred_VIE

So basically if I had told it to install the bootmanager on the nvme it would have failed because of a missing 1 gb ext4 or would it have worked?

An NVMe is a physical storage device, not a partition.

[Fred_VIE]

@Aragorn

It should be a dedicated partition, and I am advising 1 GiB

So if I would have told it on install to put the bootmanager on the nvme it would have failed because of the lack of a dedicated partition?

The two things I could do at this point is sacrifice the Win-drive, because I cba to reinstall, or to reformat the 2nd nvme which is still ntfs and used as data grave and app + general backup drive.

@Aragorn

edit your /etc/fstab to include a record for /boot.

how would that have to look like?

[Aragorn]

@Fred_VIE

So if I would have told it on install to put the bootmanager on the nvme it would have failed because of the lack of a dedicated partition?

In a system that boots in UEFI mode, you don’t “install the boot loader to a drive”. The boot loader goes in the EFI system partition, and the boot loader configuration for each respective GNU/Linux installation goes in said GNU/Linux system’s own /boot directory.

@Fred_VIE

@Aragorn

edit your /etc/fstab to include a record for /boot.

how would that have to look like?

UUID=some-long-string     /boot     ext4     defaults      0     1

[Fred_VIE]

@Aragorn

boot loader goes in the EFI system partition

Thats why I thought I could just install it onto the nvme’s existing efi system partition and put the /boot onto the ext4 partition since both Manjaro and Cachy-OS wanted to put the boot loader onto that drive anyways.

I still do not get why this is any different to making a separate 1 GB partition.

@Aragorn

An NVMe is a physical storage device, not a partition.

but the ext4 partition onto that nvme is.

[Aragorn]

@Fred_VIE

Thats why I thought I could just install it onto the nvme’s existing efi system partition and put the /boot onto the ext4 partition since both Manjaro and Cachy-OS wanted to put the boot loader onto that drive anyways.

You’re asking for trouble. You can have only one operating system claiming the same /boot partition. A UEFI boot sequence is very different from a legacy BIOS boot sequence.

[Fred_VIE]

@Aragorn

You can have only one operating system claiming the same /boot partition.

There is no operating system on any of the nvme’s partitions. All the OS’ are on other ssd’s.

If that is such a problem, than why does every Linux want it’s boot loader on the nvme to begin with?

[Aragorn]

@Fred_VIE

There is no operating system on any of the nvme’s partitions. All the OS’ are on other ssd’s.

Is there or is there not a free ext4 partition on that drive?

@Fred_VIE

If that is such a problem, than why does every Linux want it’s boot loader on the nvme to begin with?

Because it’s the one the firmware will check first at hardware boot time.

[Fred_VIE]

@Aragorn

Is there or is there not a free ext4 partition on that drive?

it’s a 2 TB ext4 partition, it has free space but it is not empty.

@Aragorn

Because it’s the one the firmware will check first at hardware boot time.

So if I would have told the Manjaro installer to use that drive for the boot loader and done the same with the Cachy-os installer, the latter would have broken the former?

[Aragorn]

@Fred_VIE

@Aragorn

Is there or is there not a free ext4 partition on that drive?

it’s a 2 TB ext4 partition, it has free space but it is not empty.

Then it won’t do. It has to be a dedicated partition, and 2 TiB is a ridiculous waste of space for /boot.

@Fred_VIE

@Aragorn

Because it’s the one the firmware will check first at hardware boot time.

So if I would have told the Manjaro installer to use that drive for the boot loader and done the same with the Cachy-os installer, the latter would have broken the former?

I think you still don’t understand what constitutes “the boot loader”. The UEFI boot process loads a distribution-specific EFI stub from the EFI system partition, and that EFI stub will load its configuration from the selected distribution’s /boot.

The EFI partition can hold multiple EFI stubs, including for other operating systems like MS-Windows. Each distribution will normally use its own /boot — this is never shared with other distributions, not even if it resides on a separate partition.

[Fred_VIE]

@Aragorn

that EFI stub will load its configuration from the selected distribution’s /boot

This is why I do not get it:

Looking at sdc1 the /boot folder is simply on the same partition (thats why it seems logical that I could copy it onto the nvme-ext4 and put it into fstab after). It is one partition with 230 GB while you are telling me it should be on a separate 1 GB partition, but neither the Manjaro nor Cachy-OS installer seem to do it that way.

and the same with SDB1:

[Aragorn]

@Fred_VIE

Looking at sdc1 the /boot folder is simply on the same partition (what thought I could do on the nvme-ext4 and put it into fstab). It is one partition with 230 GB while you are telling me it should be on a separate 1 GB partition, but neither the Manjaro nor Cachy-OS installer seem to do it that way.

Please read my post(s) again. I did not tell you that /boot should be on a separate 1 GiB partition.

What I did tell you is that if you want to keep on using btrfs for the root filesystem and you want grub to remember the last-booted entry, then you need a separate ext4 partition for /boot, and then this partition should be about 1 GiB.

The only two alternatives are…

• reinstalling your Manjaro on ext4 — and then you do not need a separate /boot; or…
• forget about having grub save the most recent boot choice.

[Fred_VIE]

@Aragorn

if you want to keep on using btrfs for the root filesystem and you want grub to remember the last-booted entry, then you need a separate ext4 partition for /boot, and then this partition should be about 1 GiB.

ic, thank you for your time!

[Molski]

@Aragorn

• reinstalling your Manjaro on ext4 — and then you do not need a separate /boot; or…
• forget about having grub save the most recent boot choice.

I have just come to accept that with btrfs, but you get so much more! It’s worth it!

For me, it also helps always wanting to boot the first entry, most of the time.

But would switching the order (while in Manjaro) be a compromise?

It should still take the first one, right @Aragorn? Or are you stuck with a Manjaro kernel here.

ls -l /etc/grub.d/
total 124
-rwxr-xr-x 1 root root  9816 Nov 22 05:52 00_header
-rwxr-xr-x 1 root root 13961 Nov 22 05:52 10_linux
lrwxrwxrwx 1 root root    34 Nov 13 01:42 15_ostree -> /usr/lib/libostree/grub2-15_ostree
-rwxr-xr-x 1 root root 14393 Nov 22 05:52 20_linux_xen
-rwxr-xr-x 1 root root   786 Nov 22 05:52 25_bli
-rwxr-xr-x 1 root root 13191 Nov 22 05:52 30_os-prober
-rwxr-xr-x 1 root root  1120 Nov 22 05:52 30_uefi-firmware
-rwxr-xr-x 1 root root   744 Nov  5 10:08 35_fwupd
-rwxr-xr-x 1 root root   214 Nov 22 05:52 40_custom
-rwxr-xr-x 1 root root   215 Nov 22 05:52 41_custom
-rwxr-xr-x 1 root root 29811 Sep 17 09:59 41_snapshots-btrfs
-rwxr-xr-x 1 root root  1219 Dec 26  2024 60_memtest86+
-rw-r--r-- 1 root root   483 Nov 22 05:52 README

[Aragorn]

@Molski

For me, it also helps always wanting to boot the first entry, most of the time.

But would switching the order (while in Manjaro be a compromise?)

It should still take the first one, right @Aragorn?

You can set the order in /etc/default/grub — note: the count starts at 0 — but then it’s statically set and will not change the default depending on what you selected.

Here’s mine…

GRUB_DEFAULT=0
GRUB_TIMEOUT=5
GRUB_TIMEOUT_STYLE=menu
GRUB_DISTRIBUTOR='Manjaro'
GRUB_CMDLINE_LINUX_DEFAULT="quiet udev.log_priority=3"
GRUB_CMDLINE_LINUX=""

# If you want to enable the save default function, uncomment the following
# line, and set GRUB_DEFAULT to saved.
# GRUB_SAVEDEFAULT=true