ubuntu启动失败the system is running in low graphics mode

ubuntu启动失败the system is running in lowg raphics mode

起因

ubuntu重新设置selinux的模式
修改配置文件/etc/selinux/config

# This file controls the state of SELinux on the system.
# SELINUX= can take one of these three values:
# enforcing - SELinux security policy is enforced.
# permissive - SELinux prints warnings instead of enforcing.
# disabled - No SELinux policy is loaded.
#SELINUX=enforcing
SELINUX=permissive
# SELINUXTYPE= can take one of these two values:
# default - equivalent to the old strict and targeted policies
# mls     - Multi-Level Security (for military and educational use)
# src     - Custom policy built from source
SELINUXTYPE=ubuntu

# SETLOCALDEFS= Check local definition changes
SETLOCALDEFS=0

其中的SELINUX=permissive即是表达当前selinux所处的模式
常用的selinux配置有三项：缺省是强制策略。
1、enforcing - 强制打开,拒绝违反安全策略
2、permissive - 遇到违反安全策略仍正常执行，但输出警告
3、disabled - 关闭安全策略

我将SELINUX设置为enforcing，导致重启后，系统启动失败，提示“the system is running in lowgraphics mode”

解决办法

进入recovery模式

1. 系统重启选择ubuntu高级，选择recovery mode
2. 在recovery Menu中选择 root Drop to root shell prompt
3. 进入命令行模式，此时根文件系统挂在的为只读，使用如下命令重新挂在
   mount -rw -o remount /
4. 修改配置文件/etc/selinux/config

参考文件

1. ubuntu的recovery mode
2. linux如何开启selinux