Bug with qxl drm driver allows screen resolution on spice sessions only to be grown, but not shrinked

[Luca Lorenzetto]

Using on trusty the kernel provided by linux-image-generic-lts-vivid (3.19.0) is affected by a bug on kernel's qxl drm driver.

When resizing the screen on a spice session, the screen gets resized only when growing the screen, not when shrinking.

Bug on fedora: https://bugzilla.redhat.com/show_bug.cgi?id=1212201

Relevant Kernel commit:

https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=bd3e1c7c6de9f5f70d97cdb6c817151c0477c5e3

Downgrading to linux-image-generic-lts-utopic (3.16.0) solved the issue.

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: xorg (not installed)
ProcVersionSignature: Ubuntu 3.19.0-28.30~14.04.1-generic 3.19.8-ckt5
Uname: Linux 3.19.0-28-generic x86_64
ApportVersion: 2.14.1-0ubuntu3.13
Architecture: amd64
CurrentDesktop: XFCE
Date: Tue Sep 15 13:19:13 2015
InstallationDate: Installed on 2014-11-27 (292 days ago)
InstallationMedia: Xubuntu 14.04.1 LTS "Trusty Tahr" - Release amd64 (20140723)
SourcePackage: xorg
Symptom: display
UpgradeStatus: No upgrade log present (probably fresh install)