[bionic] startx / xinit crashes with GLX backtrace if Composite Disabled in xorg.conf (intel mesa driver)

[Christian Niemeyer]

[New bug filed with ubuntu-bug/apport. However there was nothing to file against in /var/crashes]

For certain games I disable the Composite extension in my /etc/X11/xorg.conf when using a non-composited window manager like openbox, fluxbox or marco. Disabling the Composite extension prevents tearing in (some) games and sometimes is an additional performance boost.

This worked flawlessly in all previous Ubuntu versions including 17.10 (artful).

This stopped working with Ubuntu 18.04 (bionic). I tested with the mainline kernel 4.16 and the current 4.15 kernel in bionic-proposed and bionic. Xserver will crash with "Option "Composite" "0/False/Disable"

When I comment out the specific line in the Extensions section (that means *enabling* Composite) it works again with this xorg.conf. I can also do other stuff like disabling DRI3 or AIGLX. No crashes in these cases.

My xorg.conf:
Section "Device"
Identifier "Intel GMA45" ##just a trivial name as Identifier
Driver "intel"
EndSection

Section "Extensions"
Option "Composite" "0"
EndSection

It has a backtrace and caughts signal 6.

My Xorg.0.log:
[ 35.779]
X.Org X Server 1.19.6
Release Date: 2017-12-20
[ 35.781] X Protocol Version 11, Revision 0
[ 35.782] Build Operating System: Linux 4.4.0-101-generic x86_64 Ubuntu
[ 35.783] Current Operating System: Linux bdcomputerclub 4.16.0-994-generic #201803022100 SMP Sat Mar 3 02:03:37 UTC 2018 x86_64
[ 35.784] Kernel command line: BOOT_IMAGE=/boot/vmlinuz-4.16.0-994-generic root=UUID=cb2eb60a-9760-4805-95eb-0db77947ac82 ro quiet splash
[ 35.787] Build Date: 22 February 2018 08:04:42PM
[ 35.788] xorg-server 2:1.19.6-1ubuntu2 (For technical support please see http://www.ubuntu.com/support)
[ 35.789] Current version of pixman: 0.34.0
[ 35.792] Before reporting problems, check http://wiki.x.org
 to make sure that you have the latest version.
[ 35.792] Markers: (--) probed, (**) from config file, (==) default setting,
 (++) from command line, (!!) notice, (II) informational,
 (WW) warning, (EE) error, (NI) not implemented, (??) unknown.
[ 35.799] (==) Log file: "/home/christian/.local/share/xorg/Xorg.0.log", Time: Wed Mar 7 22:43:35 2018
[ 35.801] (==) Using config file: "/etc/X11/xorg.conf"
[ 35.803] (==) Using system config directory "/usr/share/X11/xorg.conf.d"
[ 35.803] (==) No Layout section. Using the first Screen section.
[ 35.803] (==) No screen section available. Using defaults.
[ 35.803] (**) |-->Screen "Default Screen Section" (0)
[ 35.803] (**) | |-->Monitor "<default monitor>"
[ 35.804] (==) No device specified for screen "Default Screen Section".
 Using the first device section listed.
[ 35.804] (**) | |-->Device "Intel GMA45 Express Chipset"
[ 35.804] (==) No monitor specified for screen "Default Screen Section".
 Using a default monitor configuration.
[ 35.804] (==) Automatically adding devices
[ 35.804] (==) Automatically enabling devices
[ 35.804] (==) Automatically adding GPU devices
[ 35.804] (==) Automatically binding GPU devices
[ 35.804] (==) Max clients allowed: 256, resource mask: 0x1fffff
[ 35.809] (WW) The directory "/usr/share/fonts/X11/cyrillic" does not exist.
[ 35.809] Entry deleted from font path.
[ 35.822] (==) FontPath set to:
 /usr/share/fonts/X11/misc,
 /usr/share/fonts/X11/100dpi/:unscaled,
 /usr/share/fonts/X11/75dpi/:unscaled,
 /usr/share/fonts/X11/Type1,
 /usr/share/fonts/X11/100dpi,
 /usr/share/fonts/X11/75dpi,
 built-ins
[ 35.822] (==) ModulePath set to "/usr/lib/xorg/modules"
[ 35.822] (**) Extension "Composite" is disabled
[ 35.822] (II) The server relies on udev to provide the list of input devices.
 If no devices become available, reconfigure udev or disable AutoAddDevices.
[ 35.822] (II) Loader magic: 0x55cfd2964020
[ 35.822] (II) Module ABI versions:
[ 35.822] X.Org ANSI C Emulation: 0.4
[ 35.822] X.Org Video Driver: 23.0
[ 35.822] X.Org XInput driver : 24.1
[ 35.822] X.Org Server Extension : 10.0
[ 35.824] (++) using VT number 1

[ 35.827] (II) systemd-logind: took control of session /org/freedesktop/login1/session/_32
[ 35.828] (II) xfree86: Adding drm device (/dev/dri/card0)
[ 35.829] (II) systemd-logind: got fd for /dev/dri/card0 226:0 fd 11 paused 0
[ 35.832] (--) PCI:*(0:0:2:0) 8086:2a42:1025:0459 rev 9, Mem @ 0xd0000000/4194304, 0xc0000000/268435456, I/O @ 0x000050f0/8, BIOS @ 0x????????/131072
[ 35.832] (--) PCI: (0:0:2:1) 8086:2a43:1025:0459 rev 9, Mem @ 0xd3400000/1048576
[ 35.833] (II) LoadModule: "glx"
[ 35.836] (II) Loading /usr/lib/xorg/modules/extensions/libglx.so
[ 35.850] (II) Module glx: vendor="X.Org Foundation"
[ 35.850] compiled for 1.19.6, module version = 1.0.0
[ 35.850] ABI class: X.Org Server Extension, version 10.0
[ 35.850] (II) LoadModule: "intel"
[ 35.850] (II) Loading /usr/lib/xorg/modules/drivers/intel_drv.so
[ 35.856] (II) Module intel: vendor="X.Org Foundation"
[ 35.856] compiled for 1.19.5, module version = 2.99.917
[ 35.856] Module class: X.Org Video Driver
[ 35.856] ABI class: X.Org Video Driver, version 23.0
[ 35.856] (II) intel: Driver for Intel(R) Integrated Graphics Chipsets:
 i810, i810-dc100, i810e, i815, i830M, 845G, 854, 852GM/855GM, 865G,
 915G, E7221 (i915), 915GM, 945G, 945GM, 945GME, Pineview GM,
 Pineview G, 965G, G35, 965Q, 946GZ, 965GM, 965GME/GLE, G33, Q35, Q33,
 GM45, 4 Series, G45/G43, Q45/Q43, G41, B43
[ 35.856] (II) intel: Driver for Intel(R) HD Graphics
[ 35.856] (II) intel: Driver for Intel(R) Iris(TM) Graphics
[ 35.856] (II) intel: Driver for Intel(R) Iris(TM) Pro Graphics
[ 35.856] xf86EnableIOPorts: failed to set IOPL for I/O (Operation not permitted)
[ 35.858] (II) intel(0): Using Kernel Mode Setting driver: i915, version 1.6.0 20180221
[ 35.858] (II) intel(0): SNA compiled: xserver-xorg-video-intel 2:2.99.917+git20171229-1 (Timo Aaltonen <email address hidden>)
[ 35.858] (II) intel(0): SNA compiled for use with valgrind
[ 35.876] (WW) VGA arbiter: cannot open kernel arbiter, no multi-card support
[ 35.877] (--) intel(0): Integrated Graphics Chipset: Intel(R) GM45
[ 35.877] (--) intel(0): CPU: x86-64, sse2, sse3, ssse3; using a maximum of 2 threads
[ 35.877] (II) intel(0): Creating default Display subsection in Screen section
 "Default Screen Section" for depth/fbbpp 24/32
[ 35.878] (==) intel(0): Depth 24, (--) framebuffer bpp 32
[ 35.878] (==) intel(0): RGB weight 888
[ 35.878] (==) intel(0): Default visual is TrueColor
[ 35.880] (II) intel(0): Output LVDS1 has no monitor section
[ 35.894] (**) intel(0): Found backlight control interface intel_backlight (type 'raw') for output LVDS1
[ 35.894] (II) intel(0): Enabled output LVDS1
[ 35.894] (II) intel(0): Output VGA1 has no monitor section
[ 35.894] (II) intel(0): Enabled output VGA1
[ 35.894] (II) intel(0): Output DP1 has no monitor section
[ 35.894] (II) intel(0): Enabled output DP1
[ 35.894] (--) intel(0): Using a maximum size of 256x256 for hardware cursors
[ 35.894] (II) intel(0): Output VIRTUAL1 has no monitor section
[ 35.894] (II) intel(0): Enabled output VIRTUAL1
[ 35.895] (--) intel(0): Output LVDS1 using initial mode 1366x768 on pipe 0
[ 35.895] (==) intel(0): TearFree disabled
[ 35.895] (==) intel(0): Using gamma correction (1.0, 1.0, 1.0)
[ 35.895] (==) intel(0): DPI set to (96, 96)
[ 35.895] (II) Loading sub module "dri3"
[ 35.895] (II) LoadModule: "dri3"
[ 35.895] (II) Module "dri3" already built-in
[ 35.895] (II) Loading sub module "dri2"
[ 35.895] (II) LoadModule: "dri2"
[ 35.895] (II) Module "dri2" already built-in
[ 35.895] (II) Loading sub module "present"
[ 35.895] (II) LoadModule: "present"
[ 35.895] (II) Module "present" already built-in
[ 35.895] (==) Depth 24 pixmap format is 32 bpp
[ 35.901] (II) intel(0): SNA initialized with Eaglelake (gen4.5) backend
[ 35.901] (==) intel(0): Backing store disabled
[ 35.901] (==) intel(0): Silken mouse enabled
[ 35.902] (II) intel(0): HW Cursor enabled
[ 35.902] (II) intel(0): RandR 1.2 enabled, ignore the following RandR disabled message.
[ 35.903] (==) intel(0): DPMS enabled
[ 35.904] (==) intel(0): Display hotplug detection enabled
[ 35.904] (II) intel(0): [XvMC] xvmc_vld driver initialized.
[ 35.904] (II) intel(0): [DRI2] Setup complete
[ 35.904] (II) intel(0): [DRI2] DRI driver: i965
[ 35.904] (II) intel(0): [DRI2] VDPAU driver: va_gl
[ 35.904] (II) intel(0): direct rendering: DRI2 enabled
[ 35.904] (II) intel(0): hardware support for Present enabled
[ 35.904] (--) RandR disabled
[ 35.910] (II) SELinux: Disabled on system
[ 35.961] (II) AIGLX: enabled GLX_MESA_copy_sub_buffer
[ 35.962] (II) AIGLX: enabled GLX_ARB_create_context
[ 35.962] (II) AIGLX: enabled GLX_ARB_create_context_profile
[ 35.962] (II) AIGLX: enabled GLX_EXT_create_context_es{,2}_profile
[ 35.962] (II) AIGLX: enabled GLX_INTEL_swap_event
[ 35.962] (II) AIGLX: enabled GLX_SGI_swap_control
[ 35.962] (II) AIGLX: enabled GLX_EXT_framebuffer_sRGB
[ 35.962] (II) AIGLX: enabled GLX_ARB_fbconfig_float
[ 35.962] (II) AIGLX: enabled GLX_EXT_fbconfig_packed_float
[ 35.962] (II) AIGLX: GLX_EXT_texture_from_pixmap backed by buffer objects
[ 35.962] (EE)
[ 35.962] (EE) Backtrace:
[ 35.962] (EE) 0: /usr/lib/xorg/Xorg (xorg_backtrace+0x4d) [0x55cfd26d991d]
[ 35.962] (EE) 1: /usr/lib/xorg/Xorg (0x55cfd2521000+0x1bc6b9) [0x55cfd26dd6b9]
[ 35.962] (EE) 2: /lib/x86_64-linux-gnu/libpthread.so.0 (0x7fa343473000+0x12890) [0x7fa343485890]
[ 35.962] (EE) 3: /lib/x86_64-linux-gnu/libc.so.6 (gsignal+0xc7) [0x7fa3430c0e97]
[ 35.962] (EE) 4: /lib/x86_64-linux-gnu/libc.so.6 (abort+0x141) [0x7fa3430c2801]
[ 35.963] (EE) 5: /lib/x86_64-linux-gnu/libc.so.6 (0x7fa343082000+0x3039a) [0x7fa3430b239a]
[ 35.963] (EE) 6: /lib/x86_64-linux-gnu/libc.so.6 (0x7fa343082000+0x30412) [0x7fa3430b2412]
[ 35.963] (EE) 7: /usr/lib/xorg/Xorg (0x55cfd2521000+0x3ec17) [0x55cfd255fc17]
[ 35.963] (EE) 8: /usr/lib/xorg/Xorg (0x55cfd2521000+0xe26df) [0x55cfd26036df]
[ 35.963] (EE) 9: /usr/lib/xorg/modules/extensions/libglx.so (0x7fa341437000+0x288d7) [0x7fa34145f8d7]
[ 35.963] (EE) 10: /usr/lib/xorg/modules/extensions/libglx.so (0x7fa341437000+0x2f851) [0x7fa341466851]
[ 35.963] (EE) 11: /usr/lib/xorg/modules/extensions/libglx.so (0x7fa341437000+0x27315) [0x7fa34145e315]
[ 35.963] (EE) 12: /usr/lib/xorg/Xorg (InitExtensions+0x3d) [0x55cfd25e708d]
[ 35.963] (EE) 13: /usr/lib/xorg/Xorg (0x55cfd2521000+0x56d1f) [0x55cfd2577d1f]
[ 35.963] (EE) 14: /lib/x86_64-linux-gnu/libc.so.6 (__libc_start_main+0xe7) [0x7fa3430a3b97]
[ 35.963] (EE) 15: /usr/lib/xorg/Xorg (_start+0x2a) [0x55cfd2561bba]
[ 35.963] (EE)
[ 35.963] (EE)
Fatal server error:
[ 35.963] (EE) Caught signal 6 (Aborted). Server aborting
[ 35.963] (EE)
[ 35.963] (EE)
Please consult the The X.Org Foundation support
  at http://wiki.x.org
 for help.
[ 35.963] (EE) Please also check the log file at "/home/christian/.local/share/xorg/Xorg.0.log" for additional information.
[ 35.963] (EE)
[ 36.019] (EE) Server terminated with error (1). Closing log file.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: xorg 1:7.7+19ubuntu5
ProcVersionSignature: Ubuntu 4.15.0-11.12-generic 4.15.5
Uname: Linux 4.15.0-11-generic x86_64
ApportVersion: 2.20.8-0ubuntu10
Architecture: amd64
CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins'
Date: Thu Mar 8 11:34:42 2018
DistUpgraded: Fresh install
DistroCodename: bionic
DistroVariant: ubuntu
DkmsStatus: vhba, 20170610, 4.15.0-11-generic, x86_64: installed
ExtraDebuggingInterest: Yes, if not too technical
GraphicsCard:
 Intel Corporation Mobile 4 Series Chipset Integrated Graphics Controller [8086:2a42] (rev 09) (prog-if 00 [VGA controller])
   Subsystem: Acer Incorporated [ALI] Mobile 4 Series Chipset Integrated Graphics Controller [1025:0459]
   Subsystem: Acer Incorporated [ALI] Mobile 4 Series Chipset Integrated Graphics Controller [1025:0459]
MachineType: Acer Aspire 5734Z
ProcEnviron:
 TERM=linux
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.15.0-11-generic root=UUID=cb2eb60a-9760-4805-95eb-0db77947ac82 ro quiet splash vt.handoff=1
SourcePackage: xorg
Symptom: display
Title: Xorg crash
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 04/16/2010
dmi.bios.vendor: Acer
dmi.bios.version: V1.01
dmi.board.asset.tag: Base Board Asset Tag
dmi.board.name: Aspire 5734Z
dmi.board.vendor: Acer
dmi.board.version: V1.01
dmi.chassis.type: 10
dmi.chassis.vendor: Acer
dmi.chassis.version: V1.01
dmi.modalias: dmi:bvnAcer:bvrV1.01:bd04/16/2010:svnAcer:pnAspire5734Z:pvrV1.01:rvnAcer:rnAspire5734Z:rvrV1.01:cvnAcer:ct10:cvrV1.01:
dmi.product.family: Intel_Mobile
dmi.product.name: Aspire 5734Z
dmi.product.version: V1.01
dmi.sys.vendor: Acer
version.compiz: compiz 1:0.9.13.1+18.04.20180302-0ubuntu1
version.libdrm2: libdrm2 2.4.90-1
version.libgl1-mesa-dri: libgl1-mesa-dri 18.0.0~rc4-1ubuntu3
version.libgl1-mesa-glx: libgl1-mesa-glx 18.0.0~rc4-1ubuntu3
version.xserver-xorg-core: xserver-xorg-core 2:1.19.6-1ubuntu2
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev N/A
version.xserver-xorg-video-ati: xserver-xorg-video-ati N/A
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.917+git20171229-1
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau N/A

[Christian Niemeyer (christian-niemeyer)]

tried with "strace startx"

[Christian Niemeyer (christian-niemeyer)]

Now I remove +s bit from /usr/bin/X, /usr/bin/xinit, /usr/bin/startx, /usr/bin/Xorg and tried to run Valgrind with it. Honestly I have no idea about debugging. I just know that valgrind and strace can be somehow use for it. Hope this helps!

output of valgrind -v startx 1> valgrind_v_startx.txt 2>&1

[Christian Niemeyer (christian-niemeyer)]

I suspect libglx0 (transition from libgl1-mesa-glx to libglx0)

Because now we have:
/usr/lib/x86_64-linux-gnu/libGLX.so.0.0.0 (from libglx0 in bionic, new with bionic)

instead of:
/usr/lib/x86_64-linux-gnu/mesa/ld.so.conf
/usr/lib/x86_64-linux-gnu/mesa/libGL.so.1
/usr/lib/x86_64-linux-gnu/mesa/libGL.so.1.2.0 (from libgl1-mesa-glx in artful, the packages is a transitional dummy package in bionic)

The Xorg.0.log backtrace is showing:

[ 210.258] (EE) Backtrace:
[ 210.258] (EE) 0: /usr/lib/xorg/Xorg (xorg_backtrace+0x4d) [0x5645df72591d]
[ 210.258] (EE) 1: /usr/lib/xorg/Xorg (0x5645df56d000+0x1bc6b9) [0x5645df7296b9]
[ 210.258] (EE) 2: /lib/x86_64-linux-gnu/libpthread.so.0 (0x7f00a84af000+0x12890) [0x7f00a84c1890]
[ 210.258] (EE) 3: /lib/x86_64-linux-gnu/libc.so.6 (gsignal+0xc7) [0x7f00a80fce97]
[ 210.258] (EE) 4: /lib/x86_64-linux-gnu/libc.so.6 (abort+0x141) [0x7f00a80fe801]
[ 210.258] (EE) 5: /lib/x86_64-linux-gnu/libc.so.6 (0x7f00a80be000+0x3039a) [0x7f00a80ee39a]
[ 210.258] (EE) 6: /lib/x86_64-linux-gnu/libc.so.6 (0x7f00a80be000+0x30412) [0x7f00a80ee412]
[ 210.258] (EE) 7: /usr/lib/xorg/Xorg (0x5645df56d000+0x3ec17) [0x5645df5abc17]
[ 210.258] (EE) 8: /usr/lib/xorg/Xorg (0x5645df56d000+0xe26df) [0x5645df64f6df]
[ 210.258] (EE) 9: /usr/lib/xorg/modules/extensions/libglx.so (0x7f00a6473000+0x288d7) [0x7f00a649b8d7]
[ 210.258] (EE) 10: /usr/lib/xorg/modules/extensions/libglx.so (0x7f00a6473000+0x2f851) [0x7f00a64a2851]
[ 210.258] (EE) 11: /usr/lib/xorg/modules/extensions/libglx.so (0x7f00a6473000+0x27315) [0x7f00a649a315]
[ 210.259] (EE) 12: /usr/lib/xorg/Xorg (InitExtensions+0x3d) [0x5645df63308d]
[ 210.259] (EE) 13: /usr/lib/xorg/Xorg (0x5645df56d000+0x56d1f) [0x5645df5c3d1f]
[ 210.259] (EE) 14: /lib/x86_64-linux-gnu/libc.so.6 (__libc_start_main+0xe7) [0x7f00a80dfb97]
[ 210.259] (EE) 15: /usr/lib/xorg/Xorg (_start+0x2a) [0x5645df5adbba]
[ 210.259] (EE)
[ 210.259] (EE)
Fatal server error:

However that libglx.so shown in the error log is part of xserver-xorg-core.

But I suspect it has to do with the changed to vendor neutral libglx (libglx0, libglvnd0, etc.) That would explain why it is happening with Bionic and no other versions before for me.

Can someone reproduce this? In your Display Manager switch to a VT (or deinstall display manager temporarily) and modify/create a /etc/X11/xorg.conf file with

Section "Extensions"
Option "Composite" "Disable"
EndSection

And sudo service lightdm/gdm3 stop and then try to start the Xserver/Xsession with startx or xinit.

As this is the first version of Ubuntu which seems to have this problem for

[Christian Niemeyer (christian-niemeyer)]

Just had the idea to unload "glx" and see if I can Disable Composite without crashing Xorg / startx / xinit.

It works!

Here's my xorg.conf:

Section "Module"
Disable "glx"
EndSection

Section "Extensions"
Option "Composite" "0"
EndSection

I'll put my resulting Xorg.0.log as an attachment.

However logically this prevents me from getting DRI (which I need), while glxinfo saying:
"LIBGL_DEBUG=verbose glxinfo
name of display: :0
Error: couldn't find RGB GLX visual or fbconfig"

Interesting though that Xorg no longer crashes with Composite being disabled when I disable the glx module at the same time.

[Christian Niemeyer (christian-niemeyer)]

Maybe this is i915/i965 intel driver related. If someone with an in intel IGP could reproduce this. I have xserver-xorg-video-intel installed by the way. With not mentioning "intel" explicitly as the driver in xorg.conf doesn't it automatically uses modesetting or glamorgl?

[Launchpad Janitor (janitor)]

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

[Paul van Tilburg (paulvt)]

We do have an Intel graphics card, but we just use the "modesetting" driver.

[Paul van Tilburg (paulvt)]

Similar report in Debian: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=891287
and the upstream issue report at Freedesktop Xorg upstream: https://bugs.freedesktop.org/show_bug.cgi?id=105570 (where the breaking commits are identified!).

[hovis (hovis)]

Fixed upstream according to https://bugs.freedesktop.org/show_bug.cgi?id=104993 (different upstream bug id than mentioned in the comment above)

[hovis (hovis)]

Quick way to reproduce using Xvfb on Bionic:

Xvfb :99 -screen 0 640x480x24 -ac -extension Composite

[Paul van Tilburg (paulvt)]

The commit (patch) that fixes it, is here:
https://cgit.freedesktop.org/xorg/xserver/commit/?id=1326ee0bc5eb858c3c00847b3ba65134e4ca2e2d

I can confirm that it fixes this issue if applied on top of Bionics xorg-server 2:1.19.6-1ubuntu4 source package and built.