Background: The other night, I was trying to watch a video and X locked up. I had a pacman -Syu running at the time so I decided to just leave the computer on overnight. The next morning I rebooted (I was able to ssh in from another computer; I just ran sudo reboot from the command line) but was unable to boot; after I booted from a Manjaro live environment, I found that the kernel files (vmlinuz-*) were missing from my /boot partition.
I was able to do a manjaro-chroot and reinstall kernel 4.19. But whatever grub update ran after that seems to have messed up my boot, because now I just get a blinking cursor when I attempt to boot that drive.
I'm able to boot using the Manjaro USB stick and the grub command line.
set root='hd4,gpt1' linux /vmlinuz-4.19-x86_64 root=/dev/sda3 rw rootflags=subvol=@/.snapshots/29/snapshot resume=/dev/sda2 initrd /intel-ucode.img /initramfs-4.19-x86_64.img
(where sda1 = /boot, sda2 = swap, sda3 = /, sda4 = /home)
From there I can get to a mostly functional command line. No X, and I can only log in as root. My typical user ID is not in /etc/passwd; this is a very old snapshot, my most recent one is 4672.
(Another note: I am using snapper for snapshots. I recently used
snapper delete to delete a number of old snapshots -- everything after 29 and before 3938. I don't know if this is relevant to my current problem; my understanding is that deleting old snapshots shouldn't impact the functionality of newer ones.)
From that snapshot 29 boot, I'm able to access the network and run pacman and mhwd-kernel. I wasn't able to reinstall kernel 5.3, the one I was using before; it gives me the error
linux53: /boot/linux53-x86_64.kver exists in filesystem
However, I was able to install kernels 5.4 and 5.5, since I hadn't installed them on this system before. I'm able to boot with those kernels, with the same behavior as 4.19.
Here's some diagnostic output from when I boot to snapshot 29:
When I attempt to run any other snapshot later than 29, I get a series of errors, starting with
Failed to start Load Kernel Modules
and get dumped to a "Give root password for maintenace" prompt. I'm unable to load kernel modules, mount anything besides / (which is mounted read-only), or access the network, so I'm not sure how to grab output from dmesg.
So, to summarize:
I want to be able to boot to a later snapshot
I want to fix Grub so I don't have to use command-line grub to boot.
Can anyone tell me what my next step should be? Thanks.