dual link isn't properly configured

[Scott Thompson]

System: PowerMac 7,2
Video card: Nvidia GeForce 6800 GT DDL
Display: Apple Cinema 30 inch

On this machine the desktop is shown twice vertically, full width half height. There are no other artifacts or tearing. I have another PowerMac (11,2 with Nvidia Quadro FX 4500) where this setup works correctly.

If I manually add the missing 2500x1600 mode using xrandr --output DVI-I-1 --mode 2560x1600 the xserver seems to reset immediately and go to a login screen split as above.

Ubuntu Mate 16.04
lsb_release -rd:

Description: Ubuntu 16.04.1 LTS
Release: 16.04

xserver-xorg-video-nouveau:
  Installed: 1:1.0.12-1build2
  Candidate: 1:1.0.12-1build2
  Version table:
 *** 1:1.0.12-1build2 500
        500 http://us.ports.ubuntu.com/ubuntu-ports xenial/main powerpc Packages
        100 /var/lib/dpkg/status

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: xserver-xorg-video-nouveau 1:1.0.12-1build2
ProcVersionSignature: Ubuntu 4.4.0-31.50-powerpc64-smp 4.4.13
Uname: Linux 4.4.0-31-powerpc64-smp ppc64
ApportVersion: 2.20.1-0ubuntu2.1
Architecture: powerpc
CurrentDesktop: MATE
Date: Thu Jul 21 16:48:50 2016
InstallationDate: Installed on 2016-05-30 (51 days ago)
InstallationMedia: Ubuntu-MATE 16.04 LTS "Xenial Xerus" - Release powerpc (20160420.1)
SourcePackage: xserver-xorg-video-nouveau
UpgradeStatus: No upgrade log present (probably fresh install)

[penalvch (penalvch)]

Scott Thompson, thank you for reporting this and helping make Ubuntu better.

Could you please run the following command once from a terminal by ensuring you have the package xdiagnose installed, and that you click the Yes button for attaching additional debugging information:
apport-collect 1605413

When reporting xorg related bugs in the future, please do so via the above method. You can learn more about this functionality at https://wiki.ubuntu.com/ReportingBugs.

[Launchpad Janitor (janitor)]

[Expired for xserver-xorg-video-nouveau (Ubuntu) because there has been no activity for 60 days.]