Created attachment 31700 [details]
Screenshot showing glyph corruption
After resuming from hibernation and vt switch, glyph corruption can be seen as shown in the screenshot.
Some corruption will vanish after some time, using apps like opening new web pages in Mozilla Firefox.
This started to happen rather recently (< 1 week ago). I'll try a git bisect when I have enough time.
It seems this is a bug in latest xf86-video-intel. 2.9.1 release works ok.
Can you bisect the corruption? Chris has been making some changes in this area recently.
Yes, I've already started doing this, but there is another bug caused by a later commit which makes screen and keyboard freeze after X quits. I can still ssh to the computer to issue a restart.
I will try to find the commit which causes this first and file another bug report, but as you can imagine, this makes bisecting a pain.
This may be dup with bug#25409. You can firstly try reverting that commit to see if that works.
I think VT switch behaves exactly like s&r in this regard and so it is likely to be using TILING_X for the glyph cache that is causing this apparent regression. The corruption does indeed seem identical and indicative of a tiling failure.
*** This bug has been marked as a duplicate of bug 25406 ***