Two glxgears - started with external monitor used in extended mode - each running on one of the monitors - on Sandy Bridge don't support switching to clone mode. One of the glxgears will hang.
The issue will reproduce just starting compiz.
The issue will reproduce following the test step starting compiz.But that did not happen every time.At most of time, it can switch to clone mode and one of glxgears will black-screen. platform: sugerbay Libdrm: (master)2.4.22-13-g49447a9b957047db2549b8a929e763bbd87808ba Mesa: (master)ef6967ddc201be6c400701703dd0774570d5bfee Xserver: (server-1.9-branch)xorg-server-1.9.2 Xf86_video_intel: (master)2.13.901 Cairo: (master)7ee313d7b86b8c9eeaa5bf9b42a47d3f1feaeeee Libva: (master)7d6bbcfc7709864184a9c56bfbbe4144c4d6c0c2 Kernel: (drm-intel-fixes) 3f8ff0e72d75fdbe7f2cba2c4015fd9fdd9e13fd
Created attachment 40139 [details] dmesg.log
Created attachment 40140 [details] xorg log
Tests on intel workshop show: Apparently this is fixed with the newest bits. Presumably a DRM issue.
per comment# 5, otherwise, please reopen, Gordon.
The issue is still there. The reproduce step is as below: 1,gnome-session 2,switch two monitors to extended mode with xrand. 3,run 2 glxgears. 4,ensure each glxgears running on one of the monitors. 5,switch to cloned mode. Then one of the glxgears turn to black. Note: 1, the compiz is not necessary 2, If exchange step 2 and step 3, the issue disappeared.
The issue is fixed for us. Maybe you're using an old driver stack.
Zhenyu, can you reproduce this? We can file a new bug if needed. I think Yi's stack new enough.
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