将 Ubuntu 升级到 18.04（从 17.10 开始）后，Xorg 无法启动。它只是在黑色和灰色空白屏幕之间反复切换。我重新配置了 grub 以使用 nomodeset 以文本模式启动。startx 命令无法启动 Xorg 服务器。我有一块内置的英特尔显卡。以下是 /var/log/Xorg.0.log 的输出：
[ 38.698] (II) config/udev: Adding input device HDA Intel PCH HDMI/DP,pcm=3 (/dev/input/event10)
[ 38.698] (II) No input driver specified, ignoring this device.
[ 38.698] (II) This device may have been added with another device file.
[ 38.698] (II) config/udev: Adding input device HDA Intel PCH HDMI/DP,pcm=7 (/dev/input/event11)
[ 38.698] (II) No input driver specified, ignoring this device.
[ 38.699] (II) This device may have been added with another device file.
[ 38.699] (II) config/udev: Adding input device HDA Intel PCH Rear Mic (/dev/input/event5)
[ 38.699] (II) No input driver specified, ignoring this device.
[ 38.699] (II) This device may have been added with another device file.
[ 38.699] (II) config/udev: Adding input device HDA Intel PCH Front Mic (/dev/input/event6)
[ 38.699] (II) No input driver specified, ignoring this device.
[ 38.699] (II) This device may have been added with another device file.
[ 38.699] (II) config/udev: Adding input device HDA Intel PCH Line (/dev/input/event7)
[ 38.699] (II) No input driver specified, ignoring this device.
[ 38.699] (II) This device may have been added with another device file.
[ 38.700] (II) config/udev: Adding input device HDA Intel PCH Line Out (/dev/input/event8)
[ 38.700] (II) No input driver specified, ignoring this device.
[ 38.700] (II) This device may have been added with another device file.
[ 38.700] (II) config/udev: Adding input device HDA Intel PCH Front Headphone (/dev/input/event9)
[ 38.700] (II) No input driver specified, ignoring this device.
[ 38.700] (II) This device may have been added with another device file.
[ 41.427] (**) Option "fd" "21"
[ 41.427] (II) event1 - Power Button: device removed
[ 41.427] (**) Option "fd" "24"
[ 41.427] (II) event0 - Power Button: device removed
[ 41.427] (**) Option "fd" "25"
[ 41.427] (II) event2 - PixArt USB Optical Mouse: device removed
[ 41.427] (**) Option "fd" "26"
[ 41.427] (II) event3 - USB Keyboard: device removed
[ 41.427] (**) Option "fd" "27"
[ 41.427] (II) event4 - USB Keyboard: device removed
[ 41.428] (II) UnloadModule: "libinput"
[ 41.428] (II) systemd-logind: releasing fd for 13:68
[ 41.444] (II) UnloadModule: "libinput"
[ 41.444] (II) systemd-logind: releasing fd for 13:67
[ 41.460] (II) UnloadModule: "libinput"
[ 41.460] (II) systemd-logind: releasing fd for 13:66
[ 41.512] (II) UnloadModule: "libinput"
[ 41.512] (II) systemd-logind: releasing fd for 13:64
[ 41.528] (II) UnloadModule: "libinput"
[ 41.528] (II) systemd-logind: releasing fd for 13:65
[ 41.653] (II) Server terminated successfully (0). Closing log file.
grep "(EE)" /var/log/Xorg.0.log 的输出：
[ 86.288] (EE) open /dev/dri/card0: No such file or directory
[ 86.289] (EE) open /dev/dri/card0: No such file or directory
[ 86.289] (EE) Screen 0 deleted because of no matching config section.
[ 86.294] (EE) AIGLX: reverting to software rendering