centos7
vim /etc/default/grub
#line 6 add
GRUB_CMDLINE_LINUX="ipv6.disable=1 rd.lvm.lv=VolGroup/swap rd.lvm.lv=VolGroup/usr vconsole.keymap=us crashkernel=auto vconsole.fon
t=latarcyrheb-sun16 rd.lvm.lv=VolGroup/root rhgb quiet"
执行命令:grub2-mkconfig -o /boot/grub2/grub.cfg
重启系统:reboot