我终于有时间将 KDE 桌面系统从 16.04 升级到 18.04，但现在我的第二个屏幕无法再被识别，我在 Google 上搜索过但找不到有效的方法。有人能帮我吗？到目前为止我尝试过：
我已尝试过：
$ xrandr --listmonitors
xrandr: Failed to get size of gamma for output default
Monitors: 1
0: +*default 1920/508x1080/286+0+0 default
（连接了两个显示器，一个是 DVI，另一个是 VGA），连接到 DVI 端口的屏幕当前正在工作。因此，在系统设置 - ? 显示器下，我只看到一个屏幕（默认显示器），分辨率错误（1920 x 1080）
我xrandr所看到的：
$ xrandr --listmonitors
xrandr: Failed to get size of gamma for output default
Monitors: 1
0: +*default 1920/508x1080/286+0+0 default
我尝试过的：
$ sudo dpkg-reconfigure lightdm
$ sudo systemctl restart display-manager
有人告诉我，没有必要去 NVIDIA 网页并从那里下载驱动程序。
登录后（等离子启动后），屏幕会以大约 2Hz 的频率闪烁几秒钟，直到稳定下来并显示屏幕，每边的边距约为一英寸，顶部和底部的边距可能小一点……
当我启动该nvidia-settings应用程序时，屏幕就像登录后一样闪烁，并且实际上没有出现配置应用程序，也没有在外壳上显示任何内容...
我有以下文件（/etc/X11/xorg.conf但没有）：
:/etc/X11/Xsession.d$ ls -l
total 96
-rw-r--r-- 1 root root 1062 Nov 15 2017 20dbus_xdg-runtime
-rw-r--r-- 1 root root 2030 Jan 20 2012 20x11-common_process-args
-rw-r--r-- 1 root root 878 Mar 30 2010 30x11-common_xresources
-rw-r--r-- 1 root root 389 Mar 22 2012 35x11-common_xhost-local
-rw-r--r-- 1 root root 187 Jul 1 2008 40x11-common_xsessionrc
-rw-r--r-- 1 root root 1568 May 20 2011 50x11-common_determine-startup
-rw-r--r-- 1 root root 743 Apr 19 2018 55gnome-session_gnomerc
-rw-r--r-- 1 root root 664 May 16 2015 55xfce4-session
-rw-r--r-- 1 root root 146 Jan 20 2012 60x11-common_localhost
-rw-r--r-- 1 root root 991 Apr 19 2018 60x11-common_xdg_path
-rw-r--r-- 1 root root 336 Mar 26 2014 70gconfd_path-on-session
-rw-r--r-- 1 root root 1541 Mar 21 2015 70im-config_launch
-rw-r--r-- 1 root root 123 Dec 7 2015 70xdg-kubuntu-dir
-rw-r--r-- 1 root root 752 Nov 15 2017 75dbus_dbus-launch
-rw-r--r-- 1 root root 143 Nov 28 2012 80appmenu
-rw-r--r-- 1 root root 142 Nov 28 2012 80appmenu-gtk3
-rwxr-xr-x 1 root root 2430 Sep 21 2016 80im-switch
-rw-r--r-- 1 root root 326 Apr 12 2012 80kubuntu-xmodmap
-rw-r--r-- 1 root root 1027 Feb 24 2012 90consolekit
-rw-r--r-- 1 root root 880 Nov 30 2017 90gpg-agent
-rw-r--r-- 1 root root 368 Mar 12 2018 90qt-a11y
-rw-r--r-- 1 root root 629 Mar 30 2010 90x11-common_ssh-agent
-rw-r--r-- 1 root root 513 Dec 1 2015 95dbus_update-activation-env
-rw-r--r-- 1 root root 166 Jul 1 2008 99x11-common_start
但得到：
ron@ronDesktopHome:/etc/X11/Xsession.d$ grep -rn Monitor *
ron@ronDesktopHome:/etc/X11/Xsession.d$
哈，我也试过了：
$sudo systemctl isolate multi-user.target
$sudo X -configure
并得到：
X.Org X Server 1.19.6
Release Date: 2017-12-20
X Protocol Version 11, Revision 0
Build Operating System: Linux 4.4.0-138-generic x86_64 Ubuntu
Current Operating System: Linux ronDesktopHome 4.15.0-66-generic #75-Ubuntu SMP Tue Oct 1 05:24:09 UTC 2019 x86_64
Kernel command line: BOOT_IMAGE=/boot/vmlinuz-4.15.0-66-generic root=UUID=b0488ebc-79a6-49dc-b86f-fd3d9b1d746a ro quiet splash nomdmonddf nomdmonisw nomdmonddf nomdmonisw nomdmonddf nomdmonisw nomdmonddf nomdmonisw vt.handoff=1
Build Date: 25 October 2018 04:11:27PM
xorg-server 2:1.19.6-1ubuntu4.2 (For technical support please see http://www.ubuntu.com/support)
Current version of pixman: 0.34.0
Before reporting problems, check http://wiki.x.org
to make sure that you have the latest version.
Markers: (--) probed, (**) from config file, (==) default setting,
(++) from command line, (!!) notice, (II) informational,
(WW) warning, (EE) error, (NI) not implemented, (??) unknown.
(==) Log file: "/var/log/Xorg.0.log", Time: Fri Oct 25 18:04:37 2019
(EE)
(EE) Backtrace:
(EE) 0: /usr/lib/xorg/Xorg (xorg_backtrace+0x4d) [0x5582267b98cd]
(EE) 1: /usr/lib/xorg/Xorg (0x558226601000+0x1bc669) [0x5582267bd669]
(EE) 2: /lib/x86_64-linux-gnu/libpthread.so.0 (0x7f97b448c000+0x12890) [0x7f97b449e890]
(EE) 3: /usr/lib/xorg/Xorg (0x558226601000+0xb22b4) [0x5582266b32b4]
(EE) 4: /usr/lib/xorg/Xorg (xf86BusProbe+0x9) [0x55822668b229]
(EE) 5: /usr/lib/xorg/Xorg (InitOutput+0x7f1) [0x558226699e71]
(EE) 6: /usr/lib/xorg/Xorg (0x558226601000+0x56cd3) [0x558226657cd3]
(EE) 7: /lib/x86_64-linux-gnu/libc.so.6 (__libc_start_main+0xe7) [0x7f97b40bcb97]
(EE) 8: /usr/lib/xorg/Xorg (_start+0x2a) [0x558226641b8a]
(EE)
(EE) Segmentation fault at address 0x50
(EE)
Fatal server error:
(EE) Caught signal 11 (Segmentation fault). Server aborting
(EE)
(EE)
Please consult the The X.Org Foundation support
at http://wiki.x.org
for help.
(EE) Please also check the log file at "/var/log/Xorg.0.log" for additional information.
(EE)
(EE) Server terminated with error (1). Closing log file.
Aborted
日志文件也不包含太多有用的信息，是吗？：
$ sudo cat /var/log/Xorg.0.log
[ 39519.761]
X.Org X Server 1.19.6
Release Date: 2017-12-20
[ 39519.761] X Protocol Version 11, Revision 0
[ 39519.761] Build Operating System: Linux 4.4.0-138-generic x86_64 Ubuntu
[ 39519.761] Current Operating System: Linux ronDesktopHome 4.15.0-66-generic #75-Ubuntu SMP Tue Oct 1 05:24:09 UTC 2019 x86_64
[ 39519.761] Kernel command line: BOOT_IMAGE=/boot/vmlinuz-4.15.0-66-generic root=UUID=b0488ebc-79a6-49dc-b86f-fd3d9b1d746a ro quiet splash nomdmonddf nomdmonisw nomdmonddf nomdmonisw nomdmonddf nomdmonisw nomdmonddf nomdmonisw vt.handoff=1
[ 39519.761] Build Date: 25 October 2018 04:11:27PM
[ 39519.761] xorg-server 2:1.19.6-1ubuntu4.2 (For technical support please see http://www.ubuntu.com/support)
[ 39519.761] Current version of pixman: 0.34.0
[ 39519.761] Before reporting problems, check http://wiki.x.org
to make sure that you have the latest version.
[ 39519.761] Markers: (--) probed, (**) from config file, (==) default setting,
(++) from command line, (!!) notice, (II) informational,
(WW) warning, (EE) error, (NI) not implemented, (??) unknown.
[ 39519.761] (==) Log file: "/var/log/Xorg.0.log", Time: Fri Oct 25 18:05:44 2019
[ 39519.761] (II) Loader magic: 0x5574ce79b020
[ 39519.761] (II) Module ABI versions:
[ 39519.761] X.Org ANSI C Emulation: 0.4
[ 39519.761] X.Org Video Driver: 23.0
[ 39519.761] X.Org XInput driver : 24.1
[ 39519.761] X.Org Server Extension : 10.0
[ 39519.762] (--) using VT number 3
[ 39519.762] (II) systemd-logind: logind integration requires -keeptty and -keeptty was not provided, disabling logind integration
[ 39519.763] (II) xfree86: Adding drm device (/dev/dri/card0)
[ 39519.765] (EE)
[ 39519.765] (EE) Backtrace:
[ 39519.765] (EE) 0: /usr/lib/xorg/Xorg (xorg_backtrace+0x4d) [0x5574ce50c8cd]
[ 39519.765] (EE) 1: /usr/lib/xorg/Xorg (0x5574ce354000+0x1bc669) [0x5574ce510669]
[ 39519.765] (EE) 2: /lib/x86_64-linux-gnu/libpthread.so.0 (0x7f3d8104e000+0x12890) [0x7f3d81060890]
[ 39519.765] (EE) 3: /usr/lib/xorg/Xorg (0x5574ce354000+0xb22b4) [0x5574ce4062b4]
[ 39519.765] (EE) 4: /usr/lib/xorg/Xorg (xf86BusProbe+0x9) [0x5574ce3de229]
[ 39519.765] (EE) 5: /usr/lib/xorg/Xorg (InitOutput+0x7f1) [0x5574ce3ece71]
[ 39519.765] (EE) 6: /usr/lib/xorg/Xorg (0x5574ce354000+0x56cd3) [0x5574ce3aacd3]
[ 39519.765] (EE) 7: /lib/x86_64-linux-gnu/libc.so.6 (__libc_start_main+0xe7) [0x7f3d80c7eb97]
[ 39519.765] (EE) 8: /usr/lib/xorg/Xorg (_start+0x2a) [0x5574ce394b8a]
[ 39519.765] (EE)
[ 39519.765] (EE) Segmentation fault at address 0x50
[ 39519.765] (EE)
Fatal server error:
[ 39519.765] (EE) Caught signal 11 (Segmentation fault). Server aborting
[ 39519.765] (EE)
[ 39519.765] (EE)
Please consult the The X.Org Foundation support
at http://wiki.x.org
for help.
[ 39519.765] (EE) Please also check the log file at "/var/log/Xorg.0.log" for additional information.
[ 39519.765] (EE)
[ 39519.766] (EE) Server terminated with error (1). Closing log file.