The workaround is to use Intel UXA acceleration instead of SNA:
-------------------------------------- /etc/X11/xorg.conf.d/20-intel.conf --------------------------------------
Section "Device" Identifier "Intel Graphics" Driver "intel" Option "AccelMethod" "uxa" EndSection
--------------------------------------
Of course this is only a workaround, and only LightDM is affected by Intel SNA acceleration, so I agree that this bug should be confirmed and handled.
The workaround is to use Intel UXA acceleration instead of SNA:
------- ------- ------- ------- ------- --- xorg.conf. d/20-intel. conf ------- ------- ------- ------- ---
/etc/X11/
-------
Section "Device"
Identifier "Intel Graphics"
Driver "intel"
Option "AccelMethod" "uxa"
EndSection
------- ------- ------- ------- ------- ---
Of course this is only a workaround, and only LightDM is affected by Intel SNA acceleration, so I agree that this bug should be confirmed and handled.