When I run zbarcam with a non-compositing window manager, such as openbox and xfwm with compositing disabled, it works mostly fine although it may cause the kernel to show some error: [drm:ilk_display_irq_handler] *ERROR* Pipe A FIFO underrun [drm:cpt_set_fifo_underrun_reporting] *ERROR* uncleared pch fifo underrun on pch transcoder A [drm:cpt_serr_int_handler] *ERROR* PCH transcoder A FIFO underrun When I run zbarcam with a compositing window manager, such as gnome-shell (mutter) and xfwm with compositing enabled, it also shows the above error, but it stops showing the video captured by the webcam and shows the zbar logo instead after the window is moved. If I keep moving the window for more than 30 seconds, it causes Xorg to hang and it tells me to report the bug here. The system may crash after showing the error. [drm] stuck on render ring [drm] GPU HANG: ecode 0:0x84fefffc, in Xorg.bin [1114], reason: Ring hung, action: reset [drm] GPU hangs can indicate a bug anywhere in the entire gfx stack, including userspace. [drm] Please file a _new_ bug report on bugs.freedesktop.org against DRI -> DRM/Intel [drm] drm/i915 developers can then reassign to the right component if it's not a kernel issue. [drm] The gpu crash dump is required to analyze gpu hangs, so please always attach it. [drm] GPU crash dump saved to /sys/class/drm/card0/error [drm] stuck on render ring [drm] GPU HANG: ecode 0:0x84fefffc, in Xorg.bin [1114], reason: Ring hung, action: reset Hardware: Intel Core i7-2640M CPU @ 2.80GHz Intel Sandybridge Mobile Software: Linux 3.18.5 Xorg 1.16.3 Mesa 10.4.3 xf86-video-intel 2.99.916 Window Managers: GNOME Shell 3.14.3 (Mutter 3.14.3) Openbox 3.5.2 Xfwm 4.10.1
Created attachment 113273 [details] dmesg
Created attachment 113274 [details] /sys/class/drm/card0/error
There have been some fixes related to Sandy Bridge GPU hangs made on Mesa master and on the 10.5 branch. Can you retry with the 10.5 branch?
I will try Mesa 10.5 ... An interesting thing to know is that I cannot reproduce the problem without using GDM.
(In reply to Ian Romanick from comment #3) > There have been some fixes related to Sandy Bridge GPU hangs made on Mesa > master and on the 10.5 branch. Can you retry with the 10.5 branch? I upgraded to Mesa 10.5.0-rc1 and used the same version of Xorg and xf86-video-intel, but it still hangs when I move the window of zbarcam under gnome-shell.
Created attachment 113471 [details] Linux 3.18.6, Mesa 10.5.0-rc1 dmesg
Created attachment 113472 [details] Linux 3.18.6, Mesa 10.5.0-rc1 /sys/class/drm/card0/error
Same thing. zbarcam with video feed kills the system. zbarcam --nodisplay causes no problems. Fedora 21 with Gnome Haswell graphics with SNA but crashed with UXA too mesa 10.4.3-1.20150124.fc21 kernel 3.18.7-200.fc21 xorg-x11-drv-intel 2.99.916-3.20141117.fc21
I tried git master branch. The 'FIFO underrun' messages showed, but Xorg didn't hang. However, zbarcam still stopped showing the video and showed the logo instead after the window was moved. Software: Linux 3.19.5 Xorg 1.17.99 (xorg-server-1.17.0-76-gb102971) Mesa 10.6.0-devel (10.5-branchpoint-1847-geeee212) xf86-video-intel 2.99.917-294-ge7016d3 Window Managers: Mutter 3.14.4 Openbox 3.5.2
Please reopen if you can still reproduce with Mesa 17.0.
Although zbarcam still doesn't work with compositing window managers, running it no longer causes Xorg hang or system crash. zbarcam seems to work correctly with non-compositing window managers and Xwayland. Software: Linux 4.10.15 Xorg 1.19.3 Mesa 17.0.5 xf86-video-intel 2.99.917-708-g8f33f80 Window Managers: GNOME Shell 3.22.3 (Mutter 3.22.4) Openbox 3.6.1 Xfwm 4.12.4 Wayland Compositors: GNOME Shell 3.22.3 (Mutter 3.22.4) Weston 1.12.0
I can run zbarcam on Ubuntu (Xubuntu 16.04) without issues: Kernel: 4.13.0-38-generic x86_64 Desktop: Xfce 4.12.3 (Gtk 2.24.28) with compositing enabled Mesa 10.1.0-devel (git-a61ae2a), Mesa 17.2.8 Unable to build mesa-10.4.3 (mentioned in comments) so tested with Mesa 10.4.7 (git-cb154bb) - all OK.
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