centos7
vi /etc/default/grub
GRUB_TIMEOUT=1
GRUB_DISTRIBUTOR="$(sed 's, release .*$,,g' /etc/system-release)"
GRUB_DEFAULT=saved
GRUB_DISABLE_SUBMENU=true
GRUB_TERMINAL_OUTPUT="console"
GRUB_CMDLINE_LINUX="crashkernel=0M-2G:0M,2G-8G:192M,8G-:256M cryptomgr.notests cgroup.memory=nokmem rcupdate.rcu_cpu_stall_timeout=300 vring_force_dma_api rhgb quiet biosdevname=0 net.ifnames=0 console=tty0 console=ttyS0,115200n8 noibrs"
GRUB_DISABLE_RECOVERY="true"在GRUB_CMDLINE_LINUX后面追加想配置的参数：
例如增加关闭安全策略：
noibrs noibpb nopti nospectre_v2 nospectre_v1 l1tf=off nospec_store_bypass_disable no_stf_barrier mds=off mitigations=off
GRUB_CMDLINE_LINUX="crashkernel=0M-2G:0M,2G-8G:192M,8G-:256M cryptomgr.notests cgroup.memory=nokmem rcupdate.rcu_cpu_stall_timeout=300 vring_force_dma_api rhgb quiet biosdevname=0 net.ifnames=0 console=tty0 console=ttyS0,115200n8 noibrs noibrs noibpb nopti nospectre_v2 nospectre_v1 l1tf=off nospec_store_bypass_disable no_stf_barrier mds=off mitigations=off"增加后记得生成grub.cfg
grub2-mkconfig -o /boot/grub2/grub.cfg
重启后生效。
或者直接改/boot/grub2/grub.cfg文件也可以，也是重启后生效。