diff --git a/docs/troubleshooting/intel-igfx-troubleshooting.md b/docs/troubleshooting/intel-igfx-troubleshooting.md index 2398db5..de0a35e 100644 --- a/docs/troubleshooting/intel-igfx-troubleshooting.md +++ b/docs/troubleshooting/intel-igfx-troubleshooting.md @@ -24,6 +24,46 @@ If you are unsure as to which parameter works with your kernel, check whether your kernel log from your latest boot has a message containing "i915: unknown parameter". +## Fix tearing (glithes/artifacts/corruption/...) + +By default Qubes OS uses the framebuffer/modesetting driver (`fbdev`). An issue +with `fbdev` is that without compositing VM windows exhibit graphical artefacts +(dom0 is unaffected). Workarounds: + + * enable compositing; it is enabled by default in XFCE (if it was disabled for + some reason, re-enabling it is done in "Window Manager Tweaks"; restarting + `xfwm` isn't necessary). `i3wm` users would have to install a compositing + manager (the old + [faq](https://faq.i3wm.org/question/3279/do-i-need-a-composite-manager-compton.1.html) + mentions using `compton`). + + * or switch to the `intel` driver (**for some users the `intel` driver is + unstable, triggering random crashes from oopses to hard reboots !**). + Create `/etc/X11/xorg.conf.d/20-intel.conf` and fill it with + + ``` + Section "Device" + Identifier "Intel Graphics" + Driver "Intel" + EndSection + ``` + + A logout/login is then required. + +## Finding out which of `intel` or `fbdev` driver is in use: + + * `grep -E 'LoadModule.*(fbdev|intel)"' /var/log/Xorg.0.log`; eg. for `intel`: + + ``` + (II) LoadModule: "intel" + ``` + + * or, `sudo lsof +D /usr/lib64/xorg/modules/drivers/` ; eg. for `fbdev`: + + ``` + Xorg [...] /usr/lib64/xorg/modules/drivers/modesetting_drv.so + ``` + ## IOMMU-related issues Dom0 Kernels currently included in Qubes have issues related to VT-d (IOMMU) and