После обновления Kubuntu до 15.04 пропал и не включается композитинг. Полез разбираться - в systemsettings5 / экран / обеспечение эффектов эффекты (тени, прозрачность и прочее) не работают при любых комбинациях OpenGL 2/3.1 (с сообщением в ~/.xsession-errors "kwin_core: Failed to initialize compositing, compositing disabled"), и работают при включенном Xrender. В KDE предыдущей серии, кажется, существовала настройка работы с OpenGL 1.*, и как-то так всё и работало.
Исходно - GLX версии 1.4:
System: Host: linux Kernel: 4.1.2-040102-generic i686 (32 bit) Desktop: KDE 5 Distro: Ubuntu 15.04 vivid
Graphics: Card: Intel 82G33/G31 Express Integrated Graphics Controller
Display Server: X.Org 1.17.1 drivers: intel (unloaded: fbdev,vesa) Resolution: 1280x1024@60.0hz
GLX Renderer: Mesa DRI Intel G33 x86/MMX/SSE2 GLX Version: 1.4 Mesa 10.5.2
OpenGL vendor string: Intel Open Source Technology Center
OpenGL renderer string: Mesa DRI Intel(R) G33 x86/MMX/SSE2
OpenGL version string: 1.4 Mesa 10.5.2
OpenGL shading language version string: 1.20
Driver: Intel
GPU class: i915/i945
OpenGL version: 1.4
GLSL version: 1.20
Mesa version: 10.5.2
X server version: 1.17.1
Linux kernel version: 4.1.2
Requires strict binding: yes
GLSL shaders: limited
Texture NPOT support: yes
Virtual Machine: no
Direct rendering: true
Добавляю ppa:oibaf/graphics-drivers, обновляю систему
2015-07-15 18:34:06 upgrade libass5:i386 0.12.1-1~vivid 0.12.1-2~gd~v
2015-07-15 18:34:06 upgrade libdrm2:i386 2.4.60-2 2.4.62+git1507140630.dfed5e~gd~v
2015-07-15 18:34:07 upgrade libdrm-intel1:i386 2.4.60-2 2.4.62+git1507140630.dfed5e~gd~v
2015-07-15 18:34:08 upgrade libdrm-nouveau2:i386 2.4.60-2 2.4.62+git1507140630.dfed5e~gd~v
2015-07-15 18:34:08 upgrade libdrm-radeon1:i386 2.4.60-2 2.4.62+git1507140630.dfed5e~gd~v
2015-07-15 18:34:09 upgrade libwayland-egl1-mesa:i386 10.5.2-0ubuntu1 10.7~git1507150730.7124fe~gd~v
2015-07-15 18:34:10 upgrade libllvm3.6:i386 1:3.6-2ubuntu1 1:3.6.1-1~gd~v
2015-07-15 18:34:12 upgrade libgbm1:i386 10.5.2-0ubuntu1 10.7~git1507150730.7124fe~gd~v
2015-07-15 18:34:13 upgrade libegl1-mesa:i386 10.5.2-0ubuntu1 10.7~git1507150730.7124fe~gd~v
2015-07-15 18:34:14 upgrade libgl1-mesa-dri:i386 10.5.2-0ubuntu1 10.7~git1507150730.7124fe~gd~v
2015-07-15 18:34:15 upgrade libosmesa6:i386 10.5.2-0ubuntu1 10.7~git1507150730.7124fe~gd~v
2015-07-15 18:34:15 upgrade libgles2-mesa:i386 10.5.2-0ubuntu1 10.7~git1507150730.7124fe~gd~v
2015-07-15 18:34:16 upgrade libgles1-mesa:i386 10.5.2-0ubuntu1 10.7~git1507150730.7124fe~gd~v
2015-07-15 18:34:17 upgrade libgl1-mesa-glx:i386 10.5.2-0ubuntu1 10.7~git1507150730.7124fe~gd~v
2015-07-15 18:34:17 upgrade libglapi-mesa:i386 10.5.2-0ubuntu1 10.7~git1507150730.7124fe~gd~v
2015-07-15 18:34:18 upgrade libva-drm1:i386 1.5.0-1 1.5.1-1~gd~v
2015-07-15 18:34:19 upgrade libva1:i386 1.5.0-1 1.5.1-1~gd~v
2015-07-15 18:34:19 upgrade libva-x11-1:i386 1.5.0-1 1.5.1-1~gd~v
2015-07-15 18:34:20 upgrade libva-glx1:i386 1.5.0-1 1.5.1-1~gd~v
2015-07-15 18:34:21 upgrade libvdpau1:i386 0.9-1 1.1-1~gd~v
2015-07-15 18:34:22 upgrade libxatracker2:i386 10.5.2-0ubuntu1 10.7~git1507150730.7124fe~gd~v
2015-07-15 18:34:22 upgrade xserver-xorg-video-radeon:i386 1:7.5.0-1ubuntu2 1:7.5.99+git1507100730.b6d871~gd~v
2015-07-15 18:34:23 upgrade xserver-xorg-video-ati:i386 1:7.5.0-1ubuntu2 1:7.5.99+git1507100730.b6d871~gd~v
2015-07-15 18:34:24 upgrade xserver-xorg-video-intel:i386 2:2.99.917-1~exp1ubuntu2.2 2:2.99.917+git1507101930.2c5063~gd~v
2015-07-15 18:34:25 upgrade xserver-xorg-video-nouveau:i386 1:1.0.11-1ubuntu2build1 1:1.0.11+git1507150732.5212db~gd~v
Рестарт иксов, получаем OpenGL 2.0, рендеринг через Gallium
System: Host: linux Kernel: 4.1.2-040102-generic i686 (32 bit) Desktop: KDE 5 Distro: Ubuntu 15.04 vivid
Graphics: Card: Intel 82G33/G31 Express Integrated Graphics Controller
Display Server: X.Org 1.17.1 drivers: intel (unloaded: fbdev,vesa) Resolution: 1280x1024@60.0hz
GLX Renderer: Gallium 0.4 on i915 (
GLX Version: 2.1 Mesa 10.7.0-devel (git-7124feb 2015-07-15 vivid-oibaf-ppa)
Композитинг при выборе OpenGL 2 включается, но куча артефактов отрисовки, изменение параметров масштабирования - без эффекта.
Откатываю. Пробую ppa:xorg-edgers/ppa, обновляюсь
2015-07-15 21:20:51 upgrade libdrm2:i386 2.4.60-2 2.4.62+git20150703.676c806d-0ubuntu0ricotz~vivid
2015-07-15 21:20:52 upgrade libdrm-intel1:i386 2.4.60-2 2.4.62+git20150703.676c806d-0ubuntu0ricotz~vivid
2015-07-15 21:20:52 upgrade libdrm-nouveau2:i386 2.4.60-2 2.4.62+git20150703.676c806d-0ubuntu0ricotz~vivid
2015-07-15 21:20:53 upgrade libdrm-radeon1:i386 2.4.60-2 2.4.62+git20150703.676c806d-0ubuntu0ricotz~vivid
2015-07-15 21:20:54 upgrade libwayland-egl1-mesa:i386 10.5.2-0ubuntu1 10.6.1~git20150703+10.6.6ff3ae8d-0ubuntu0ricotz~vivid
2015-07-15 21:20:54 upgrade libgbm1:i386 10.5.2-0ubuntu1 10.6.1~git20150703+10.6.6ff3ae8d-0ubuntu0ricotz~vivid
2015-07-15 21:20:55 upgrade libegl1-mesa:i386 10.5.2-0ubuntu1 10.6.1~git20150703+10.6.6ff3ae8d-0ubuntu0ricotz~vivid
2015-07-15 21:20:56 upgrade libgl1-mesa-dri:i386 10.5.2-0ubuntu1 10.6.1~git20150703+10.6.6ff3ae8d-0ubuntu0ricotz~vivid
2015-07-15 21:20:57 upgrade libosmesa6:i386 10.5.2-0ubuntu1 10.6.1~git20150703+10.6.6ff3ae8d-0ubuntu0ricotz~vivid
2015-07-15 21:20:57 upgrade libgles2-mesa:i386 10.5.2-0ubuntu1 10.6.1~git20150703+10.6.6ff3ae8d-0ubuntu0ricotz~vivid
2015-07-15 21:20:58 upgrade libgles1-mesa:i386 10.5.2-0ubuntu1 10.6.1~git20150703+10.6.6ff3ae8d-0ubuntu0ricotz~vivid
2015-07-15 21:20:59 upgrade libgl1-mesa-glx:i386 10.5.2-0ubuntu1 10.6.1~git20150703+10.6.6ff3ae8d-0ubuntu0ricotz~vivid
2015-07-15 21:20:59 upgrade libglapi-mesa:i386 10.5.2-0ubuntu1 10.6.1~git20150703+10.6.6ff3ae8d-0ubuntu0ricotz~vivid
2015-07-15 21:21:00 upgrade libglamor0:i386 0.6.0-0ubuntu4 0.6.0+git20140801.347ef4f0-0ubuntu0sarvatt
2015-07-15 21:21:01 upgrade libvdpau1:i386 0.9-1 1.1-0ubuntu1~xedgers15.04.1
2015-07-15 21:21:01 upgrade libxatracker2:i386 10.5.2-0ubuntu1 10.6.1~git20150703+10.6.6ff3ae8d-0ubuntu0ricotz~vivid
2015-07-15 21:21:11 upgrade ppa-purge:all 0.2.8+bzr57 0.2.8+bzr57+edgers2
2015-07-15 21:21:11 upgrade xserver-xorg-video-radeon:i386 1:7.5.0-1ubuntu2 1:7.5.99+git20150521.d64a13eb-0ubuntu0ricotz~vivid
2015-07-15 21:21:12 upgrade xserver-xorg-video-ati:i386 1:7.5.0-1ubuntu2 1:7.5.99+git20150521.d64a13eb-0ubuntu0ricotz~vivid
2015-07-15 21:21:13 upgrade xserver-xorg-video-intel:i386 2:2.99.917-1~exp1ubuntu2.2 2:2.99.917+git20150708.e5c6e48c-0ubuntu0sarvatt~vivid
2015-07-15 21:21:14 upgrade xserver-xorg-video-nouveau:i386 1:1.0.11-1ubuntu2build1 1:1.0.11+git20150708.dfd827ce-0ubuntu0sarvatt~vivid
Рестарт иксов, на выходе снова OpenGL 1.4. Композитинг снова пропадает.
System: Host: linux Kernel: 4.1.2-040102-generic i686 (32 bit) Desktop: KDE 5 Distro: Ubuntu 15.04 vivid
Graphics: Card: Intel 82G33/G31 Express Integrated Graphics Controller
Display Server: X.Org 1.17.1 drivers: intel (unloaded: fbdev,vesa) Resolution: 1280x1024@60.0hz
GLX Renderer: Mesa DRI Intel G33 x86/MMX/SSE2 GLX Version: 1.4 Mesa 10.6.1
Сижу вот думаю - оставить XRender (а чем кстати плохо?), или добиваться OpenGL 2.0?
Смущает, что на тестовой машине под арчем с аналогичным G31 чипсетом композитинг при OpenGL 2.0 работает без нареканий, то есть возможно же...
System: Host: urm2 Kernel: 4.0.7-2-ARCH x86_64 (64 bit) Desktop: KDE Plasma 5.12.0 Distro: Arch Linux
Graphics: Card: Intel 82G33/G31 Express Integrated Graphics Controller
Display Server: X.Org 1.17.2 drivers: intel (unloaded: fbdev,vesa) Resolution: 1280x1024@60.02hz
GLX Renderer: Mesa DRI Intel G33 GLX Version: 2.1 Mesa 10.6.2
OpenGL vendor string: Intel Open Source Technology Center
OpenGL renderer string: Mesa DRI Intel(R) G33
OpenGL version string: 2.1 Mesa 10.6.2
OpenGL shading language version string: 1.20
Driver: Intel
GPU class: i915/i945
OpenGL version: 2.1
GLSL version: 1.20
Mesa version: 10.6.2
X server version: 1.17.2
Linux kernel version: 4.0.7
Requires strict binding: yes
GLSL shaders: limited
Texture NPOT support: yes
Virtual Machine: no