Xmir (DRI2 mode) crashes when launching chromium

[Michael Terry]

I've installed xserver-xorg-xmir, unity8-desktop-session-mir, and set my lightdm seat type to "unity". Using normal everyday unity-greeter and unity7 session with xmir, most things work well.

The one thing that doesn't is trying to launch chromium. Doing so takes down the xmir session entirely. Looking at the log file, I see:

(==) Log file: "/var/log/Xorg.0.log", Time: Wed Feb 11 15:23:28 2015
(==) Using system config directory "/usr/share/X11/xorg.conf.d"
Driver needs flags 0, incompatible with nested, deleting.
Driver needs flags 0, incompatible with nested, deleting.
Driver needs flags 1, incompatible with nested, deleting.
(EE)
(EE) Backtrace:
(EE) 0: /usr/bin/X (xorg_backtrace+0x56) [0x7fd0feaa7806]
(EE) 1: /usr/bin/X (0x7fd0fe8f0000+0x1bb9e9) [0x7fd0feaab9e9]
(EE) 2: /lib/x86_64-linux-gnu/libc.so.6 (0x7fd0fc5c5000+0x36eb0) [0x7fd0fc5fbeb0]
(EE) 3: /usr/lib/xorg/modules/drivers/intel_drv.so (0x7fd0f6544000+0x6ea04) [0x7fd0f65b2a04]
(EE) 4: /usr/lib/xorg/modules/drivers/intel_drv.so (0x7fd0f6544000+0x10d280) [0x7fd0f6651280]
(EE) 5: /usr/bin/X (0x7fd0fe8f0000+0x186edc) [0x7fd0fea76edc]
(EE) 6: /usr/bin/X (DRI2CopyRegion+0x8b) [0x7fd0fea7786b]
(EE) 7: /usr/bin/X (0x7fd0fe8f0000+0x189b53) [0x7fd0fea79b53]
(EE) 8: /usr/bin/X (0x7fd0fe8f0000+0x57257) [0x7fd0fe947257]
(EE) 9: /usr/bin/X (0x7fd0fe8f0000+0x5b466) [0x7fd0fe94b466]
(EE) 10: /lib/x86_64-linux-gnu/libc.so.6 (__libc_start_main+0xf5) [0x7fd0fc5e6ec5]
(EE) 11: /usr/bin/X (0x7fd0fe8f0000+0x4577e) [0x7fd0fe93577e]
(EE)
(EE) Segmentation fault at address 0xffffffffffffff00
(EE)
Fatal server error:
(EE) Caught signal 11 (Segmentation fault). Server aborting
(EE)
(EE)
Please consult the The X.Org Foundation support
  at http://wiki.x.org
 for help.
(EE) Please also check the log file at "/var/log/Xorg.0.log" for additional information.
(EE)
(II) AIGLX: Suspending AIGLX clients for VT switch
(EE) Server terminated with error (1). Closing log file.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Rick Harris (rickfharris)]

Same here, also using the Intel driver but happens in Vivid using Unity7.

It appears any GL application in a Mir session will hard crash the session back to lightdm greeter.

Am able to reproduce the same crash by using 'glxgears'.

[Rick Harris (rickfharris)]

BTW, the chromium crash is worked around by disabling hardware acceleration in chromium's settings.

[Rick Harris (rickfharris)]

Full backtrace of crash.

Seems also to be related to bug #1450581

[Daniel van Vugt (vanvugt)]

XMir 1.0 (the old Xorg extension) is now deprecated and is not being maintained or fixed. It is replaced by the new 'Xmir' binary (package 'xmir') introduced in Ubuntu 15.10 wily.

Is there any way to reproduce this bug without the old Xmir?

[Daniel van Vugt (vanvugt)]

Confirmed even with trunk Xmir... Although Xmir doesn't crash it does show errors with Chromium:

Focus: unfocused
chromium-browser --type=gpu-process --channel=29964.0.243176076 --v8-natives-passed-by-fd --v8-snapshot-passed-by-fd --supports-dual-gpus=false --gpu-driver-bug-workarounds=2,15,44,56 --disable-accelerated-video-decode --gpu-vendor-id=0x8086 --gpu-device-id=0x0412 --gpu-driver-vendor --gpu-driver-version --v8-natives-passed-by-fd --v8-snapshot-passed-by-: Could not find mir surface for swapping!
[DRI2] DRI2SwapBuffers: driver failed to schedule swap

Looks like maybe Chromium is confused and trying to speak native Mir and X/GLX simultaneously..?

[Daniel van Vugt (vanvugt)]

Sorry the problem is indeed just pure Xmir. The above error comes from xmir-dri2.c

[Daniel van Vugt (vanvugt)]

Workaround: Use software mode:

Xmir -sw -damage

[Daniel van Vugt (vanvugt)]

Sorry, I got my bugs confused.

This crash seems to have been fixed as I've done some major reworking of Xmir (trunk) over the past couple of months. Including improved stability.

However I still see some visual bugs unique to Chromium. Will log them separately.

[Daniel van Vugt (vanvugt)]

The remaining issue has moved to bug 1510025.

[Daniel van Vugt (vanvugt)]

xorg-server (2:1.17.3-2ubuntu2) xenial; urgency=medium