VirtualBox guest
Running arch as a VBox gues
Stop your virtual machine.
Install the extension pack for VirtualBox.
Start your virtual machine and install virtualbox-guest-utils.
pacman -S virtualbox-guest-utils
Choose virtualbox-guest-modules-arch.
Reboot your virtual machine.
Add your user to vboxsf group.
usermod -aG vboxsf root
Create a shared folder on VirtualBox.
Reboot your virtual machine.
Mount your folder to test.
Umount the volume.
Edit your fstab.
Add this line (example).
Mount it.