Added the upstream bug to this tracker. Then I realized that strictly speaking this bug "X doesn't start with r128 driver (ATI RAGE) [powerpc]" has a different meaning from this one here "blotchy graphics". I think it's best to create a new Ubuntu Xorg bug and add the upstream info there.
Sorry for the noise! @Fritz: Your xorg.conf looks fine. After altering parameters check your Xorg.log after you restarted X, to look what exactly went wrong with the driver you selected xorg.conf. Just use the different drivers "modesetting", "fbdev", "fbdevhw" with different bit depths and see what happens. If your monitor is capacle also always use the native resolution of your monitor. The Rage 128 is able to do 1920x1080 if you got the most recent PM 3,1 (http://identimac.com/modelDetails/Power%20Macintosh%20G4/23.html) -- You received this bug notification because you are a member of Desktop Packages, which is subscribed to xorg in Ubuntu. https://bugs.launchpad.net/bugs/1541082 Title: [PowerMac3,1] Blotchy GUI graphics for images Status in xorg package in Ubuntu: New Bug description: The background image and other image files are blotchy. --- ApportVersion: 2.20.1-0ubuntu2.1 Architecture: powerpc BootLog: fsck from util-linux 2.27.1 /dev/sda13: clean, 182266/1458176 files, 1099215/5826607 blocks CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins' CompositorRunning: None DistUpgraded: Fresh install DistroCodename: xenial DistroRelease: Ubuntu 16.04 DistroVariant: ubuntu DpkgLog: ExtraDebuggingInterest: Yes, if not too technical GraphicsCard: Advanced Micro Devices, Inc. [AMD/ATI] Rage 128 PRO AGP 4x TMDS [1002:5046] (prog-if 00 [VGA controller]) InstallationDate: Installed on 2016-01-31 (154 days ago) InstallationMedia: Ubuntu-MATE 16.04 LTS "Xenial Xerus" - Alpha powerpc (20160123) Lsusb: Bus 002 Device 004: ID 047d:1029 Kensington Mouse*in*a*Box Optical Elite Bus 002 Device 003: ID 05ac:0220 Apple, Inc. Aluminum Keyboard (ANSI) Bus 002 Device 002: ID 05ac:1006 Apple, Inc. Hub in Aluminum Keyboard Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 001 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Package: xorg 1:7.7+13ubuntu3 PackageArchitecture: powerpc ProcEnviron: LANGUAGE=en_US TERM=xterm PATH=(custom, no user) LANG=en_US.UTF-8 SHELL=/bin/bash ProcKernelCmdLine: root=UUID=4eb514e5-48d7-4e99-a402-5294c80e78cc ro quiet splash ProcVersionSignature: Ubuntu 4.4.0-24.43-powerpc-smp 4.4.10 Renderer: Software Tags: xenial ubuntu Uname: Linux 4.4.0-24-powerpc-smp ppc UpgradeStatus: No upgrade log present (probably fresh install) UserGroups: _MarkForUpload: True version.compiz: compiz 1:0.9.12.2+16.04.20160526-0ubuntu1 version.libdrm2: libdrm2 2.4.67-1ubuntu0.16.04.1 version.libgl1-mesa-dri: libgl1-mesa-dri 11.2.0-1ubuntu2 version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A version.libgl1-mesa-glx: libgl1-mesa-glx 11.2.0-1ubuntu2 version.xserver-xorg-core: xserver-xorg-core 2:1.18.3-1ubuntu2.2 version.xserver-xorg-input-evdev: xserver-xorg-input-evdev 1:2.10.1-1ubuntu2 version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:7.7.0-1 version.xserver-xorg-video-intel: xserver-xorg-video-intel N/A version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.12-1build2 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xorg/+bug/1541082/+subscriptions -- Mailing list: https://launchpad.net/~desktop-packages Post to : desktop-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~desktop-packages More help : https://help.launchpad.net/ListHelp