00xserver-xgl_start-server Should Be Optional

[Jonathan Anderson]

Binary package hint: xserver-xgl

Recent versions of the xserver-xgl package install a file /etc/X11/Xsession.d/00xserver-xgl_start-server. This file starts Xgl for regular X sessions, which totally breaks performance when using non-accelerated drivers (like Avivo).

This behaviour should really be optional, perhaps reconfigurable through dpkg-reconfigure.

I post this bug because it took me quite awhile to hunt down the reason that my Avivo performance died between two days ago and yesterday. I don't think that such a major change shouldn't happen in such a non-obvious way.

[Chris Halse Rogers (raof)]

The script is installed under the assumption that a user who installs Xgl wants to use Xgl. It should be possible to modify the script so that it is easily disabled if there's a good use-case for having Xgl installed and not wanting to use it, however. Alternatively we could add avivo to the list of blacklisted drivers, or try to determine whether Xgl is likely to have acceptable performance, but that's much harder.

If you can provide us with the reasons you have xgl installed and are using an non-accelerated driver that will help to decide between these alternatives.

[Jarmo Ilonen (trewas)]

I had xserver-xgl installed for some reason, maybe I tried it during edgy... Anyway the package has been installed since then and hasn't caused problems until this upgrade. I guess that's my own fault, but it sure took some time debugging why X got totally borked (running like without acceleration, wrong keyboard settings, any gl app crashing whole X, etc)... This using i810 and intel drivers with 915GM.

Anyway, I doubt I am alone having "stale" xserver-xorg package installed, popcon.ubuntu.com says installed 14317 and vote 2390, meaning that vast majority of xserver-xorg installations are unused and will only serve to break X for the user. At least some warning would help people fix their x-servers.

[Jarmo Ilonen (trewas)]

A couple of clarifications, so I had xserver-xgl installed without (ever) using it, and of course I meant "stale" xserver-xgl, not xserver-xorg... The numbers are for the xserver-xgl package.

[Chris Halse Rogers (raof)]

Hm. Some of those sound like fixable bugs, and Xgl should work fine on Intel cards. Xgl should work fine on any card that provides 3d acceleration, really.

Anyway, the next package will include an upgrade-notifier message indicating that Xgl will now be started automatically. That should give people enough of a warning, if a little late.

[Jonathan Anderson (jonathan-anderson)]

I had xserver-xgl installed from the dark days before Avivo, when I had to run the binary ATI driver.

I still keep it around when I want to see the current state of "bling" on the Linux desktop... not a very important reason, sure, but Jarmo's statistics indicate that I may not be alone.

I'm not an expert, but I know my way around the command line. For somebody a little fresher (who might still install Xgl because somebody in a Compiz forum told them they needed it), figuring a problem like this out could be thorny.

I handle Xgl in /usr/share/xsessions (but then I need separate .desktop files for KDE and GNOME with Xgl).

Anything else I can share?

[Chris Halse Rogers (raof)]

That seems to be enough. I'll see about making the auto-start able to be disabled on a per-user basis. I still think that enabled-by-default is the right setting, though.

[Victor Sergienko (singalen)]

One more here. Just spent 4 days trying to figure out how to get back ordinary X server.

1. We have sessions in /usr/share/xsessions. If Xgl is started from that session, user will be able to select on startup, whether he wants Xgl or not.
2. A real bug: uninstalling xserver-xgl with dpkg -r didn't remove 00xserver-xgl_start-server.
Maybe because it's marked as a config file, while it's actually an executable.
This renders all the system non-workable till someone removes it by hand.

I suggest it to be critical bug in Xgl package.

[Chris Halse Rogers (raof)]

xserver-xgl (1:1.1.99.1~git20070727-0ubuntu2) gutsy; urgency=low

  * debian/xserver-xgl-notification.update-notifier
    + Inform users that we start Xgl automatically, so previously set up Xgl
      sessions may not work correctly.
  * Remove old Xsession.d file on install, if it hasn't been modified
    (LP: #136962). New Xsession.d file won't fall over after xserver-xgl is
    uninstalled.
  * debian/00-xserver-xgl_start-server
    + Split into a wrapper script debian/Xgl-session, and install this into
      /usr/bin and a much smaller debian/98-xserver-xgl_start-server file.
    + Install Xsession file to 98-xserver-xgl_start-server, so that it's at
      the top of the $STARTUP stack instead of starting Xgl first in the
      Xsession.d process. Fixes startup for those who manually installed
      the fglrx drivers (and possibly others).
  * Add a killswitch to disable Xgl on a per-user basis. If the file
    ~/.config/xserver-xgl/disable exists, Xgl will not be automatically
    started. Documented in README.Debian. (LP: #136878)

 -- Christopher James Halse Rogers (RAOF) <email address hidden> Tue, 04 Sep 2007 12:57:34 +1000

[Jonathan Anderson (jonathan-anderson)]

That's great... thanks!