On Monday, 17 April 2023 14:31:08 BST Mark Knecht wrote:
> My needs are quite simple but efibootmgr, set up by the Kubuntu install
> on a separate M.2 from the Windows install the machine came with, works for
> me. I always start the day in Kubuntu, then reboot to Windows if I'm working
> on music:
>
> 1) The simple view of the two installations:
>
> mark@science2:~$ efibootmgr
> BootCurrent: 0003
> Timeout: 1 seconds
> BootOrder: 0003,0000
> Boot0000* Windows Boot Manager
> Boot0003* ubuntu
> mark@science2:~$
>
> 2) The more complicated view with GUIDs and such:
>
> mark@science2:~$ efibootmgr -v
> BootCurrent: 0003
> Timeout: 1 seconds
> BootOrder: 0003,0000
> Boot0000* Windows Boot Manager
> HD(1,GPT,2052c843-0057-494a-a749-e8ec3676514a,0x800,0x32000)/File(\EF
> I\MICROSOFT\BOOT\BOOTMGFW.EFI)WINDOWS.........x...B.C.D.O.B.J.E.C.T.=.{.9.d.
> e.a.8.6.2.c.-.5.c.d.d.-.4
> .e.7.0.-.a.c.c.1.-.f.3.2.b.3.4.4.d.4.7.9.5.}....................
> Boot0003* ubuntu
> HD(1,GPT,2052c843-0057-494a-a749-e8ec3676514a,0x800,0x32000)/File(\EFI\UBUN
> TU \SHIMX64.EFI)
> mark@science2:~$
This shows the efibootmgr is using the first disk and boots the Windows
BOOTMGFW.EFI, or Ubuntu's shimX64.efi from there.
> 3) To get to Windows I can choose it in the OS screen if I'm sitting there
> but the most reliable way for me to get from Kubuntu to Windows is to just
> tell the system to go to Windows at the next boot using a batch file in
> Kubuntu:
>
> mark@science2:~$ cat bin/RebootWindows
> sudo efibootmgr -n 0000
> reboot
> mark@science2:~$
>
> The 'problem' with this setup is that all of the grub/efibootmgr stuff
> is on both drives
Are you sure?
> and I'm never sure which drive is being used at
> which time as I have Kubuntu on nvme1 and Windows boot
> manager on nvme0 which I'm never comfortable with but the
> Ubuntu stuff figured it out so I don't argue. Pity me if I ever have to
> do a reinstall.
>
> mark@science2:~$ df -h
> Filesystem Size Used Avail Use% Mounted on
> tmpfs 3.2G 3.7M 3.2G 1% /run
> /dev/nvme1n1p3 916G 622G 248G 72% /
> tmpfs 16G 66M 16G 1% /dev/shm
> tmpfs 5.0M 4.0K 5.0M 1% /run/lock
> /dev/nvme0n1p1 96M 32M 65M 33% /boot/efi
This is where the ESP is mounted, but you'll find /boot directory is on your /
dev/nvme1n1p3 block device, along with your kernels, initrd images and
vimlinuz symlinks.
Your GRUB EFI bootable image is on /dev/nvme0n1p1, under /boot/efi/EFI/ubuntu/
> tmpfs 3.2G 64K 3.2G 1% /run/user/1000
> mark@science2:~$
I would think Ubuntu installed GRUB on nvme0n1p1 ESP, which it detected by
scanning your disks. If your nvme0n1p1 fails and has to be removed, you will
need to create a new ESP somewhere on the ubuntu disk and then you can
reinstall GRUB after you reboot with a LiveUSB, or while still running ubuntu.
