1.进livecd
2.sudo fdisk -l 找到安装分区
3.sudo mount /dev/sda? /mnt 挂载安装分区
4.sudo mount --bind /dev /mnt/dev
sudo mount --bind /proc /mnt/proc
sudo mount --bind /sys /mnt/sys
5.sudo chroot /mnt
6.grub-install /dev/sda
7.grub-mkconfig -o /boot/grub/grub.cfg