You boot into a live cd (probably the arch install disc) and rsync on to a mounted partition, then you chroot into that partition and re-install the bootloader.

You boot into a live cd (probably the arch install disc) and rsync on to a mounted partition, then you chroot into that partition and re-install the bootloader. This is pretty much how you install archlinux normally, except instead of rsync-ing the initial filesystem you make a new initial filesystem based on the "filesystem" package. https://archlinux.org/packages/core/x86_64/filesystem/ https://archlinux.org/packages/core/x86_64/filesystem/