Re: kern/55198: When the video card is Intel Mobile 965GM Express,i915drmkms has error CPU pipe A FIFO underrun, also X freezes/hangs

[Izumi Tsutsui <tsutsui%ceres.dti.ne.jp@localhost>]

The following reply was made to PR kern/55198; it has been noted by GNATS.

From: Izumi Tsutsui <tsutsui%ceres.dti.ne.jp@localhost>
To: joaopaulo1511%hotmail.com@localhost
Cc: gnats-bugs%netbsd.org@localhost, tsutsui%ceres.dti.ne.jp@localhost
Subject: Re: kern/55198: When the video card is Intel Mobile 965GM Express,i915drmkms
	 has error CPU pipe A FIFO underrun, also X freezes/hangs
Date: Thu, 30 Apr 2020 03:19:37 +0900

 > I could make X work after I added the "AccelMethod" "uxa" line to both of the two sections created on xorg.conf.new by X -configure (It didn't occurred me earlier to do that, sorry).
 > 
 > So I think the easiest fix would make "uxa" the default acceleration method on old chips as Intel 965GM.
 
 Mine is N455 GMA 3150.  Maybe all GMA Intel GPUs are affected?
  https://en.wikipedia.org/wiki/Intel_GMA#Generation_three_based
  GMA 900  (910G, 915G, 915Gx)
  GMA 950  (945G)
  GMA 3100 (Q33, G35, G31, G33)
  GMA 3150 (Atom D4xx, D5xx, N4xx, N5xx)
 etc.
 
 ("SNA" seems to stand for "Sandybridge's New Acceleration").
  https://en.wikipedia.org/wiki/SNA_(computer_graphics)
 
 > Could you please in the meantime add a suggestion to fix this error on "http://netbsd.org/docs/guide/en/chap-x.html#chap-x-configuration"; page?
 
 I've surveyed how we can change xorg.conf simpler, and then
 it's turned out it's enough to have the following simple
 /etc/X11/xorg.conf just to change only the "AccelMethod":
 
 ---
 Section "Device"
 	Identifier "Intel Gen3 GPU workaround"
 	Driver     "intel"
         Option     "AccelMethod" "uxa"
 EndSection
 ---
 
 Maybe we should an independent section about the trouble shooting?
 
 ---
 Izumi Tsutsui