mkinitcpio

mkinitcpio is a script to create an initial ramdisk environment.

Troubleshooting

'/lib/modules/xxxxxxx' is not a valid kernel module directory

When you encounter an error like the header of this section when running
mkinitcpio try first to reinstall the linux, linux-headers and
filesystem packages.
If that does not fix it continue.
Look into the /lib/modules directory.
There should be a directory called 4.9.8-1-ARCH or similar.
Now run mkinitcpio -k 4.9.8-1-ARCH -g /boot/image.img and move the image
to the correct location /boot/initramfs-linux.img in the boot directory (back
up the old one).
After that reboot and it should again work fine (Source:
Unix Stackexchange).