After running a system update pacman -Syu with the testing repo not commented, my computer no longer boots. It shows the udev loading, then shows a black screen with a cursor blinking in upper left. I cannot type, or switch tty. What logs should I look at for help? When Looking at verbose boot, it says
/bin/sh can't access tty
and I can't type anything at the prompt.
This is how I fixed this problem :
I've booted into an arch installation CD and mounted my root partition under /mnt/arch.
mkdir /mnt/arch
mount /dev/sda4 /mnt/arch
I then ran the following commands:
cd /mnt/arch
mount -t proc proc proc/
mount -t sysfs sys sys/
mount -o bind /dev dev/
Depending on your file system, you may need to bind-mount different partitions and folders. Don't forget to check if the boot partition is properly mounted:
ls /mnt/arch/boot
If the boot folder is empty, you need to find the partition lsblk -f and mount (let's use sda1 as boot partition in this example:) mount /dev/sda1 /mnt/arch/boot
I then issued the chroot command and configured my network:
arch-chroot . /bin/bash
dhcpcd eth0
I'm not sure if all of these commands are required, but I didn't feel like continuously rebooting/chrooting, so I did them all at once and it fixed the issue we both were having:
pacman -Syy
pacman -Syu
pacman -S udev
pacman -S mkinitcpio
mkinitcpio -p linux
reboot
Remove the CD or USB drive and ta-da! Now, I'll be honest and admit that I don't fully understand this fix. Some of the posts also suggested doing a “pacman -S linux”, however that was not necessary for me.
-o bind mounts to properly point subfolders from the encrypted LUKS partition and I had to mount a different nvme boot partition to /boot), but after correctly mounting the stuff, it worked like charm. You are a hero!
Hopefully you can still boot into single user mode if the problem is only with the display. Otherwise you boot a live CD, mount your drive(s) and then chroot to gain access to your system.
After that the first thing you should do is to check /var/log/pacman.log to see what may have broken your system. I would suspect an update to xorg or the kernel to cause problems like this. What to do next depends entirely on the package to be fixed.
Please forgive if I'm mistaken, but perhaps you missed the on-screen message that Pacman output when you performed the upgrade. Those are generally important, especially to a rolling release distro like Arch. To quote the ArchWiki:
It is essential that users read all information output by pacman and use common sense.
