Grub issues with multiboot

[ParadoxDelta]

Hi, thank you very much for your tutorial. In my case I want to install OVM on the same drive with a Windows 10 installation to have a backup gaming machine. So my setup deviates in 2 points. The first is that I had to install OVM on top of a minimal debian setup (wich I suppose isn't a problem) and my partition structure is different (wich I suppose causes my problems). Windows occupies nvme0n1p1 to nvme0n1p3. cfdisk forced me to make nvme0n1p4 an extend volume in order to fit the 3 additional partitions for ovm (nvme0n1p5 = /boot, nvme0n1p6= swap, nvme0n1p7 = /).

Now formatting, encrypting and mounting works fine, but i get a lot of warnings for this part: update-initramfs -u -k all update-grub grub-install /dev/nvme0n1

first initramfs has some warnings: perl: warning: Setting locale failed. perl: warning: Please check that your locale settings: LANGUAGE = (unset), LC_ALL = (unset), LANG = "en_US.UTF-8" are supported and installed on your system. perl: warning: Falling back to the standard locale ("C"). perl: warning: Setting locale failed. perl: warning: Please check that your locale settings: LANGUAGE = (unset), LC_ALL = (unset), LANG = "en_US.UTF-8" are supported and installed on your system. perl: warning: Falling back to the standard locale ("C"). update-initramfs: Generating /boot/initrd.img-4.19.0-12-amd64 dropbear: WARNING: Setting DROPBEAR in /etc/initramfs-tools/initramfs.conf is deprecated and will be ignored in a future release W: Possible missing firmware /lib/firmware/nvidia/gp100/gr/sw_method_init.bin for module nouveau ... W: mkconf: MD subsystem is not loaded, thus I cannot scan for arrays. W: mdadm: failed to auto-generate temporary mdadm.conf file. update-initramfs: Generating /boot/initrd.img-4.19.0-11-amd64 dropbear: WARNING: Setting DROPBEAR in /etc/initramfs-tools/initramfs.conf is deprecated and will be ignored in a future release ... W: mkconf: MD subsystem is not loaded, thus I cannot scan for arrays. W: mdadm: failed to auto-generate temporary mdadm.conf file.

and then update-grub endlessly shows the same warning for all partitions: Generating grub configuration file ... Found background image: /usr/share/images/desktop-base/desktop-grub.png Found linux image: /boot/vmlinuz-4.19.0-12-amd64 Found initrd image: /boot/initrd.img-4.19.0-12-amd64 Found linux image: /boot/vmlinuz-4.19.0-11-amd64 Found initrd image: /boot/initrd.img-4.19.0-11-amd64 WARNING: Device /dev/nvme0n1 not initialized in udev database even after waiting 10000000 microseconds. WARNING: Device /dev/loop0 not initialized in udev database even after waiting 10000000 microseconds. WARNING: Device /dev/sda not initialized in udev database even after waiting 10000000 microseconds.

When I try to boot OVM, grub lists Debian and Windows. Windows works but Debian shows an error with the old UUID that could not be found as well as the missing vmlinuz-4.19.0-12-amd64. I tried to manually enter the new UUID in the grub.cfg but the missing vmlinuz-4.19.0-12-amd64 stays. I suspect either the extended volume structure, some legacy vs uefi or some deprecated functions to be the issue. Any idea how to fix this?