Is there a standard HOWTO I can follow to fix the boot process (to go from a grub / xen.cfg that fails to LUKS decrypt and load unencrypted rootfs)
I am reasonably knowledgeable about Linux. Gaps exist in my knowledge regarding BIOS and UEFI boot processes.
Unfortunately the grub update for the kernel upgrade seems to have messed up the boot process. How do I figure out if it’s installed for BIOS or UEFI mode ?
My data is safe and LUKS encrypted . I can use a live USB to decrypt it, access it and I also have made 2 backup copies.
So with nothing to lose I tried to fix the boot manually from a live USB including creating /etc/default/grub but situation is no better.
Between BIOS / (UEFI) / grub2 / xen / vmlinuz / LUKS / LVM2 , I am lost where the fix might be. Might be grub flags, grub modules, grub defaults, xen cfg, EFI manager etc. Hence my question.
What is exactly your problem? Does it boot, you see xen/linux messages
but fail before asking for your luks passphrase?
Maybe it is just a linux kernel problem and you can boot an older
version editing xen.cfg (if you are using UEFI boot without grub). Do
you have installed kernel-latest versions?
Is there a standard HOWTO I can follow to fix the boot process (to go
from a grub / xen.cfg that fails to LUKS decrypt and load unencrypted
rootfs)
Not that I know. Would be helpful, indeed.
Unfortunately the grub update for the kernel upgrade seems to have
messed up the boot process. How do I figure out if it's installed for
BIOS or UEFI mode ?
That is in your BIOS. If it is "legacy" it means old-school MBR, if not
it should be written UEFI somewhere.
My data is safe and LUKS encrypted . I can use a live USB to decrypt it,
access it and I also have made 2 backup copies.
good.
So with nothing to lose I tried to fix the boot manually from a live USB
including creating /etc/default/grub but situation is no better.
I had similar problems recently. If it is UEFI (and I guess so),
efibootmgr is your friend (not preinstalled on debian-live, but you grab
it easily via apt-get). Also look the "UEFI troubleshooting" qubes
webpage! You can re-do the qubes boot entry with efibootmgr (please read
the man page, syntax is not memorisable for me). Good luck, Bernhard
It was a problem with the efi boot details. I had installed the latest kernel (not manually) and that install process somehow messed up the efi boot as it existed. After boot was broken, the console would show what it was going to boot but the xen never loaded. Now it does.
Thank you donoban, Bernhard, and Jinoh for the right pointers.
I have made a list of steps that helped me gauge the situation. I will post it within a few hours.