boot an alternate kernel

[Ralf Mardorf]

On Thu, 26 May 2022 12:59:52 -0700, Bob wrote:
>I did the update-grub command but it did not work.

Hi,

what output did you get?

>I have two partitions with Ubuntu installed SDA2 and SDA9 on the
>computer. SDA9 is the main partition with a separate home, SDA2 is a
>small partition with root and home.  I have run software updates on
>both partitions many times and have not had problems even if they did
>update grub.
>
>This time the update for grub from SDA9 did not work.  I finally
>booted SDA2 and ran update-grub which worked.  In the past it appeared
>that update grub worked from either partition.  Should it work from
>only one partition or should it work from either partition?

Hi,

update-grub calls grub-mkconfig.

"If you are trying to run grub-mkconfig in a chroot or systemd-nspawn
container, you might notice that it does not work: grub-probe: error:
failed to get canonical path of /dev/sdaX." -
https://wiki.archlinux.org/title/GRUB

I suspect that the above isn't the issue you are experiencing. You
probably installed GRUB 2 times. One is the GRUB used by the boot order
of your BIOS settings, the other GRUB is unused. You are likely booted
to the wrong install and generating the menu.cfg for the unused GRUB.

Regards,
Ralf