Corrupted display in graphical Emacs with HEAD intel and SNA
Submitted by Andy Wingo
Assigned to Chris Wilson
Since updating to intel xorg driver b57abe20 and still the case with git master, graphical-mode Emacs shows corruption when using SNA (the default). I am on a thinkpad x1 carbon 3rd gen, but many other people see this on other machines:
I see corruption ranging from what appears to be tiles not updating but also small issues like certain letters not rendering. I work around it, very sadly, with M-x redraw-display, which always fixes the display. I guess there is some incremental update path that graphical Emacs hits that I don't see usually. I run in Gnome Shell FWIW so there is a compositor in the middle.
I don't know when this started, as I don't update very frequently. It only happens in graphical Emacs; no other program. Although Emacs had updated when I upgraded Xorg, I tried running the older, known-working copy as well and had the same issues with run under the new Xorg driver. Setting the system to use UXA instead of SNA fixes the issue.
We have many people that would be happy to test any proposed fixes :) Thanks for all your work over the years and thanks in advance for having a look!