unity-scope-tool tries to use the Mir plugin on X11

[James Henstridge]

When I run unity-scope-tool (version 7.85+14.04.20140410.1-0ubuntu1), it segfaults after printing the following error:

    ...
    Need to use QMirServerApplication
    file:///usr/share/unity8/Dash/DashApps.qml:20:1: plugin cannot be loaded for module "Unity.Application": Cannot load library /usr/lib/x86_64-linux-gnu/unity8/qml/Unity/Application/libunityapplicationplugin.so: (dlopen: cannot load any more object with static TLS)
    Segmentation fault (core dumped)

I did a quick web search for similar errors, which turned up this:

    http://stackoverflow.com/questions/14892101/cannot-load-any-more-object-with-static-tls

It seems that only a certain number of libraries compiled with -ftls-model=initial-exec can be loaded, after which this error occurs. It also says that initial-exec mode is default for non-PIC code, if that helps.

libunityapplicationplugin.so comes from libunity-mir1, which has version 0.3+14.04.20140401.1-0ubuntu1.

I'll attach a full log of stdout/stderr.

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: unity-scope-tool 7.85+14.04.20140410.1-0ubuntu1
ProcVersionSignature: Ubuntu 3.13.0-12.32-generic 3.13.4
Uname: Linux 3.13.0-12-generic x86_64
ApportVersion: 2.14.1-0ubuntu2
Architecture: amd64
CurrentDesktop: Unity
Date: Fri Apr 11 10:46:50 2014
InstallationDate: Installed on 2013-10-29 (163 days ago)
InstallationMedia: Ubuntu 13.10 "Saucy Salamander" - Release amd64 (20131016.1)
SourcePackage: unity8
UpgradeStatus: Upgraded to trusty on 2013-11-28 (133 days ago)

[James Henstridge (jamesh)]

And here's the full stdout/stderr log.

[Launchpad Janitor (janitor)]

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

[James Henstridge (jamesh)]

After digging a bit further, libraries that can trigger this have the DF_STATIC_TLS flag set in the DT_FLAGS entry of the dynamic section. This can be checked for with:

    readelf --dynamic library.so | grep FLAGS

libunityapplicationplugin.so is not to blame here, but a number of its dependencies might have triggered it:

/lib/x86_64-linux-gnu/libm.so.6
 0x000000000000001e (FLAGS) STATIC_TLS
/lib/x86_64-linux-gnu/libc.so.6
 0x000000000000001e (FLAGS) STATIC_TLS
/lib/x86_64-linux-gnu/libpthread.so.0
 0x000000000000001e (FLAGS) STATIC_TLS
/lib/x86_64-linux-gnu/librt.so.1
 0x000000000000001e (FLAGS) STATIC_TLS
/usr/lib/x86_64-linux-gnu/mesa/libGL.so.1
 0x000000000000001e (FLAGS) STATIC_TLS
/usr/lib/x86_64-linux-gnu/mesa-egl/libEGL.so.1
 0x000000000000001e (FLAGS) STATIC_TLS
/usr/lib/x86_64-linux-gnu/mesa-egl/libGLESv2.so.2
 0x000000000000001e (FLAGS) STATIC_TLS
/usr/lib/x86_64-linux-gnu/libglapi.so.0
 0x000000000000001e (FLAGS) STATIC_TLS
/lib/x86_64-linux-gnu/libresolv.so.2
 0x000000000000001e (FLAGS) STATIC_TLS

[Michał Sawicz (saviq)]

On 11.04.2014 03:59, James Henstridge wrote:
> When I run unity-scope-tool (version 7.85+14.04.20140410.1-0ubuntu1), it
> segfaults after printing the following error:

The error basically means it's trying to use the Mir backend for
applications instead of the fake one. Something must've gone wrong with
dependencies.

Can you please check out:

apt-cache policy unity8 unity8-private unity8-fake-env

[James Henstridge (jamesh)]

unity8:
  Installed: 7.85+14.04.20140410.1-0ubuntu1
  Candidate: 7.85+14.04.20140410.1-0ubuntu1
  Version table:
 *** 7.85+14.04.20140410.1-0ubuntu1 0
        500 http://ftp.iinet.net.au/pub/ubuntu/ trusty/universe amd64 Packages
        100 /var/lib/dpkg/status
     7.84+14.04.20140116-0ubuntu1 0
        400 http://ppa.launchpad.net/ubuntu-unity/daily-build/ubuntu/ trusty/main amd64 Packages
unity8-private:
  Installed: 7.85+14.04.20140410.1-0ubuntu1
  Candidate: 7.85+14.04.20140410.1-0ubuntu1
  Version table:
 *** 7.85+14.04.20140410.1-0ubuntu1 0
        500 http://ftp.iinet.net.au/pub/ubuntu/ trusty/universe amd64 Packages
        100 /var/lib/dpkg/status
     7.84+14.04.20140116-0ubuntu1 0
        400 http://ppa.launchpad.net/ubuntu-unity/daily-build/ubuntu/ trusty/main amd64 Packages
unity8-fake-env:
  Installed: (none)
  Candidate: 7.85+14.04.20140410.1-0ubuntu1
  Version table:
     7.85+14.04.20140410.1-0ubuntu1 0
        500 http://ftp.iinet.net.au/pub/ubuntu/ trusty/universe amd64 Packages
     7.84+14.04.20140116-0ubuntu1 0
        400 http://ppa.launchpad.net/ubuntu-unity/daily-build/ubuntu/ trusty/main amd64 Packages

[James Henstridge (jamesh)]

Installing unity8-fake-env seems to have made unity-scope-tool load correctly again. The dlopen error still sounds like a potential problem though.

[Michał Sawicz (saviq)]

Yeah, we'll have to rejig our deps, then... Feels like the tool should always depend on -fake-env... Fortunately it won't need it at all soon.

Adding a unity-mir task to see about the dlopen.

[Launchpad Janitor (janitor)]

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

[kevin gunn (kgunn72)]

surely this isn't a bug anymore ?

[Michał Sawicz (saviq)]

Right, it's not, because we don't have DashApps any more.