今天早上我尝试解决登录循环问题，并重新安装了 gdm3 包：
sudo apt-get purge gdm3
sudo apt-get install gdm3
重新启动后，我的带有 GUI 的屏幕现在看起来像这样，但 tty3 控制台看起来很正常。
我有显示器：acer v193hqv 和显卡：Radeon X1600 xrandr 显示当前分辨率为 1366x768 和 59.69 刷新率。
UPD：输入startx无效，出现xf86EnableIOPorts: failed to set IOPL for I/O (Operation not permitted)错误
完整日志可在此处查看https://pastebin.com/Gn2rZGPE
(WW) 警告和 (EE) 错误如下：
[ 166.203] (WW) The directory "/usr/share/fonts/X11/cyrillic" does not exist.
[ 166.203] Entry deleted from font path.
[ 166.203] (WW) The directory "/usr/share/fonts/X11/100dpi/" does not exist.
[ 166.203] Entry deleted from font path.
[ 166.203] (WW) The directory "/usr/share/fonts/X11/75dpi/" does not exist.
[ 166.203] Entry deleted from font path.
[ 166.203] (WW) The directory "/usr/share/fonts/X11/100dpi" does not exist.
[ 166.203] Entry deleted from font path.
[ 166.203] (WW) The directory "/usr/share/fonts/X11/75dpi" does not exist.
[ 166.203] Entry deleted from font path.
[ 167.651] xf86EnableIOPorts: failed to set IOPL for I/O (Operation not permitted)
[ 167.651] (II) [KMS] Kernel modesetting enabled.
[ 167.651] (WW) Falling back to old probe method for modesetting
[ 167.651] (WW) Falling back to old probe method for fbdev
[ 167.754] (EE) open /dev/fb0: Permission denied
[ 167.754] (WW) VGA arbiter: cannot open kernel arbiter, no multi-card support
[ 168.035] (WW) RADEON(0): 3 ZaphodHeads crtcs unavailable. Some outputs will stay off.