Actually I just tried the 4.6 kernel that was officially released 2 days ago, and I still get a freeze when attaching monitor to HDMI. However the symptoms are different.
The external monitor does get the desktop drawn on it, and I can move the mouse around, and between the monitors. But the interface is otherwise frozen: the clock on the screen stops "ticking" and no windows can be interacted with. Also cannot hit CTRL+ALT+F3 to get to a tty screen. Furthermore the logging in syslog is different: May 18 13:29:58 squan /usr/lib/gdm3/gdm-x-session[1313]: (--) intel(0): HDMI max TMDS frequency 300000KHz May 18 13:29:58 squan /usr/lib/gdm3/gdm-x-session[1313]: (II) intel(0): resizing framebuffer to 7680x2160 May 18 13:29:58 squan /usr/lib/gdm3/gdm-x-session[1313]: (II) intel(0): switch to mode 3840x2160@60.0 on eDP1 using pipe 1, position (0, 0), rotation normal, reflection none May 18 13:29:59 squan /usr/lib/gdm3/gdm-x-session[1313]: (II) intel(0): switch to mode 3840x2160@30.0 on HDMI1 using pipe 0, position (3840, 0), rotation normal, reflection none May 18 13:29:59 squan /usr/lib/gdm3/gdm-x-session[1313]: (--) intel(0): HDMI max TMDS frequency 300000KHz May 18 13:30:04 squan systemd[1]: Starting Stop ureadahead data collection... May 18 13:30:04 squan systemd[1]: Stopped Read required files in advance. May 18 13:30:04 squan systemd[1]: Started Stop ureadahead data collection. May 18 13:30:05 squan /usr/lib/gdm3/gdm-x-session[1313]: (EE) [mi] EQ overflowing. Additional events will be discarded until existing events are processed. May 18 13:30:05 squan /usr/lib/gdm3/gdm-x-session[1313]: (EE) May 18 13:30:05 squan /usr/lib/gdm3/gdm-x-session[1313]: (EE) Backtrace: May 18 13:30:05 squan /usr/lib/gdm3/gdm-x-session[1313]: (EE) 0: /usr/lib/xorg/Xorg (xorg_backtrace+0x4e) [0x55e9082ae50e] May 18 13:30:05 squan /usr/lib/gdm3/gdm-x-session[1313]: (EE) 1: /usr/lib/xorg/Xorg (mieqEnqueue+0x253) [0x55e90828ffd3] May 18 13:30:05 squan /usr/lib/gdm3/gdm-x-session[1313]: (EE) 2: /usr/lib/xorg/Xorg (QueuePointerEvents+0x52) [0x55e908168672] May 18 13:30:05 squan /usr/lib/gdm3/gdm-x-session[1313]: (EE) 3: /usr/lib/xorg/Xorg (xf86PostMotionEvent+0xd6) [0x55e90819fb56] May 18 13:30:05 squan /usr/lib/gdm3/gdm-x-session[1313]: (EE) 4: /usr/lib/xorg/modules/input/synaptics_drv.so (0x7f50831b1000+0x6056) [0x7f50831b7056] May 18 13:30:05 squan /usr/lib/gdm3/gdm-x-session[1313]: (EE) 5: /usr/lib/xorg/modules/input/synaptics_drv.so (0x7f50831b1000+0x7682) [0x7f50831b8682] May 18 13:30:05 squan /usr/lib/gdm3/gdm-x-session[1313]: (EE) 6: /usr/lib/xorg/Xorg (0x55e9080fc000+0x94248) [0x55e908190248] May 18 13:30:05 squan /usr/lib/gdm3/gdm-x-session[1313]: (EE) 7: /usr/lib/xorg/Xorg (0x55e9080fc000+0xb9712) [0x55e9081b5712] May 18 13:30:05 squan /usr/lib/gdm3/gdm-x-session[1313]: (EE) 8: /lib/x86_64-linux-gnu/libc.so.6 (0x7f508c80d000+0x354a0) [0x7f508c8424a0] May 18 13:30:05 squan /usr/lib/gdm3/gdm-x-session[1313]: (EE) 9: /usr/lib/xorg/Xorg (0x55e9080fc000+0x1b6cf0) [0x55e9082b2cf0] May 18 13:30:05 squan /usr/lib/gdm3/gdm-x-session[1313]: (EE) 10: /lib/x86_64-linux-gnu/libc.so.6 (0x7f508c80d000+0x354a0) [0x7f508c8424a0] May 18 13:30:05 squan /usr/lib/gdm3/gdm-x-session[1313]: (EE) 11: /lib/x86_64-linux-gnu/libc.so.6 (ioctl+0x7) [0x7f508c909687] May 18 13:30:05 squan /usr/lib/gdm3/gdm-x-session[1313]: (EE) 12: /usr/lib/x86_64-linux-gnu/libdrm.so.2 (drmIoctl+0x28) [0x7f508dbef0f8] May 18 13:30:05 squan /usr/lib/gdm3/gdm-x-session[1313]: (EE) 13: /usr/lib/xorg/modules/drivers/intel_drv.so (0x7f50889e1000+0x763ea) [0x7f5088a573ea] May 18 13:30:05 squan /usr/lib/gdm3/gdm-x-session[1313]: (EE) 14: /usr/lib/xorg/modules/drivers/intel_drv.so (0x7f50889e1000+0x106c39) [0x7f5088ae7c39] May 18 13:30:05 squan /usr/lib/gdm3/gdm-x-session[1313]: (EE) 15: /usr/lib/xorg/modules/drivers/intel_drv.so (0x7f50889e1000+0x108571) [0x7f5088ae9571] May 18 13:30:05 squan /usr/lib/gdm3/gdm-x-session[1313]: (EE) 16: /usr/lib/xorg/Xorg (DRI2SwapBuffers+0x1c8) [0x55e908280a98] May 18 13:30:05 squan /usr/lib/gdm3/gdm-x-session[1313]: (EE) 17: /usr/lib/xorg/Xorg (0x55e9080fc000+0x18632c) [0x55e90828232c] May 18 13:30:05 squan /usr/lib/gdm3/gdm-x-session[1313]: (EE) 18: /usr/lib/xorg/Xorg (0x55e9080fc000+0x53bbf) [0x55e90814fbbf] May 18 13:30:05 squan /usr/lib/gdm3/gdm-x-session[1313]: (EE) 19: /usr/lib/xorg/Xorg (0x55e9080fc000+0x57c43) [0x55e908153c43] May 18 13:30:05 squan /usr/lib/gdm3/gdm-x-session[1313]: (EE) 20: /lib/x86_64-linux-gnu/libc.so.6 (__libc_start_main+0xf0) [0x7f508c82d830] May 18 13:30:05 squan /usr/lib/gdm3/gdm-x-session[1313]: (EE) 21: /usr/lib/xorg/Xorg (_start+0x29) [0x55e90813df59] May 18 13:30:05 squan /usr/lib/gdm3/gdm-x-session[1313]: (EE) May 18 13:30:05 squan /usr/lib/gdm3/gdm-x-session[1313]: (EE) [mi] These backtraces from mieqEnqueue may point to a culprit higher up the stack. May 18 13:30:05 squan /usr/lib/gdm3/gdm-x-session[1313]: (EE) [mi] mieq is *NOT* the cause. It is a victim. May 18 13:30:05 squan /usr/lib/gdm3/gdm-x-session[1313]: (EE) [mi] EQ overflow continuing. 100 events have been dropped. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1568865 Title: [drm:intel_cpu_fifo_underrun_irq_handler [i915_bpo]] *ERROR* CPU pipe B FIFO underrun To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1568865/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
