手工启动 set root(hd0,msdos7)
linux /boot/vmlinuz-3.9.8-300.fc19.i686.PAE root=/dev/sda7
initrd /boot/initramfs-3.9.8-300.fc19.i686.PAE.img
boot
重建grub.cfg
grub2-mkconfig -o /boot/grub2/grub.cfg
grub2
原文：http://www.cnblogs.com/xieqianli/p/4216300.html
