If you find yourself in a position in which you're running Arch Linux and your file systems are based on LVM, RAID, or both, and when you upgrade your kernel your system won't boot because the kernel isn't running the lvm2 hook, here's how to fix it.

0. create an arch live stick and boot it
1. mount your root partition to /mnt on the live stick
2. mount your /proc partition to /mnt/proc using mount -t procfs proc /mnt/proc
3. mount your /sys partition to /mnt/sys using mount -t sysfs sys /mnt/sys
4. mount your /dev partition to /mnt/dev using mount -t tmpdevfs dev /mnt/dev
5. mount your /boot partition to /mnt/boot
6. chroot into /mnt using chroot /mnt
7. now perform pacman -Syu and watch your kernel being built.
8. finally type exit and reboot. remove your stick and boot into your now working arch linux.