RHBA-2012:1503 - Bug Fix Advisory

Topic

An updated qxl-win package that fixes a bug and offers enhancements is now
available.

Description

The qxl-win package contains the QXL driver for Windows guests. It provides a
paravirtualized display driver that reduces CPU usage on the host and provides
better performance by reducing the network bandwidth required for most
workloads.

This update fixes these bugs:

• Switching users or logging off Windows guests while dynamic content was being

displayed sometimes caused memory corruption. This ultimately led to a Stop
Error (also known as Blue Screen of Death, or BSOD) in the guest. The driver has
been updated to ensure that this does not occur when switching users or logging
off. (BZ#731644)

• In previous releases performance issues were sometimes encountered when using

the QXL driver to draw off screen surfaces. As a workaround for this issue a new
"DisableSurfaces" registry key is now supported. If the new key is set to any
value, including 0, then drawing of off screen surfaces is disabled. (BZ#851171)

To set the "DisableSurfaces" key:

1) Launch the regedit.exe executable.

2) Find the "HARDWARE\\DEVICEMAP\\VIDEO\\Device\\Video0" entry. This key
contains the UUID of the video device currently in use.

3) Find the
"Computer\KKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Video\{uuid}\0000\"
entry - replacing {uuid} with the UUID that was located in the previous step.
Create the "DisabledSurfaces" key inside the entry.

This update includes this enhancement:

• When resizing a SPICE client window, the Windows display resolution could only

be adjusted to do a best match in order to avoid black borders or scaling. The
previous driver only supported a limited set of resolutions. By adding arbitrary
resolution, the guest display can be adjusted to fit exactly to the client
window for any size. (BZ#830907)

This updated package is released as part of the rhevm-guest-tools package
advisory (RHBA-2012:1504):

https://rhn.redhat.com/errata/RHBA-2012-1504.html

Red Hat Enterprise Virtualization Manager users that are using SPICE to connect
to their virtual machines are advised to update their QXL driver.

Solution

Before applying this update, make sure all previously-released errata
relevant to your system have been applied.

This update is available via the Red Hat Network. Details on how to
use the Red Hat Network to apply this update are available at
https://access.redhat.com/knowledge/articles/11258

Affected Products

• Red Hat Virtualization 3.1 x86_64

Fixes

• BZ - 830907 - [RFE] support arbitrary guest resolution
• BZ - 851171 - RFE: add registry option to disable off screen surfaces

CVEs

(none)

References

• https://access.redhat.com/knowledge/articles/11258
• https://rhn.redhat.com/errata/RHBA-2012-1504.html