drivers - How do I eliminate screen tearing on 14.04 and XBMC with NVidia-331?

I have updated my 12.04 HTPC to 14.04 (new install; same hardware), and have started getting awful screen tearing where I had none before.

/proc/cpuinfo

AMD A4-3300 APU with Radeon(tm) HD Graphics

lspci

...

01:00.0 VGA compatible controller: NVIDIA Corporation GT218 [GeForce 210] (rev a2)

...

lsmod

...

nvidia 10675249 71

drm 302631 2 nvidia

...

Everything is from the official repos.

xbmc_12.3+dfsg1-3ubuntu1_all.deb

nvidia-331_331.38-0ubuntu7_amd64.deb

I too had this problem after upgrading to 14.04

The solution mentioned here worked wonders for me,

https://bugs.launchpad.net/ubuntu/+source/xorg-server/+bug/1278012/comments/12

A workaround for ubuntu 14.04 with nvidia driver is to disable backing store in xorg:
Make sure you have the "-bs" option in lightdm config file:

cat /usr/share/lightdm/lightdm.conf.d/50-xserver-command.conf

[SeatDefaults]
# Dump core
xserver-command=X -bs -core

---

If you're using another mechanism for starting X you can use the same flag in a similar way. For example, here's startx which is popularly used in XBMC (and other kiosk applications') startup scripts:

startx /etc/X11/Xsession /usr/bin/xbmc-standalone -- -bs