Re: Degugging DRI

On 12/30/06, Aprak Ofatys <[email protected]> wrote:
> I have problems with a (Ubuntu) laptop with a i915 based gfx with certain
> OpenGL applications.
>
> glxinfo rapports that DRI is enabled and programs like glxgears and ppracer
> works with good frame rates. However, when trying to run applications based
> on the OGRE framework, all I get is a black scene. Disabling DRI makes the
> same programs render the scenes.
>
>  I've carefully read a lot of problem info's and FAQ's the past days, and I
> still can't figure this out. I suspect it could somehow be related to DRI
> (either a bug or bad configuration).
>
> I haven't played around with OpenGL for some years, so DRI is completely new
> to me. I struggle to understand how everything fit's together so that I at
> least can isolate where _not_ to look.
>
> From this link (http://dri
> .freedesktop.org/wiki/DriTroubleshooting) I however I
> noticed some things that seem suspicious.
>
>
> Under "User Space setup" it says that dri drivers should be located in
> /usr/X11R6/lib/modules/dri/ , on my system these are located in
> /usr/lib/dri/ , Which would be the correct location?
> Also It says that glxinfo should output "libGL: OpenDriver: trying
> /usr/X11R6/lib/modules/dri/<name>_dri.so". This is not the
> case on my system. I've followed the hints and reinstalled libGL just to
> make sure no old or obsolete version is contaminating the system (Ubuntu
> actually seems to have an issue with this file if nvidia drivers has
> previously been installed on the system). The file belonged to the package
> libgl1-mesa, but reinstalling it did not make any difference.
> Neither 'export LIBGL_DEBUG=verbose' nor setting any other environment
> variables seems to make any difference. Unless I'm missing something
> obvious, setting this variable in a shell from where a OpenGL program is
> run, should mean outputting some debug info on the stdout/stderr?
> The system-wide configuration file /etc/drirc (mentioned in
> http://dri.freedesktop.org/wiki/ConfigurationInfrastructure)
> does not exist.
>
> I can't figure out which part of the system is responsible for loading
> /usr/lib/dri/i915_dri.so. Running 'ldd /usr/lib/libGL.so' doesn't seem to
> imply any dependency on any DRI libraries.
>
> Any hint's about how to debug the various layers involved would be most
> welcome.  Is it possible to profile libGL .so in any way so that calls to
> each function results in output in some file in case there actually exists a
> bug and I need to isolate exactly where?
>
> Any advice is welcome.
>
>  Regards
> /Michael

Try by setting LD_PRELOAD=/usr/lib/libGL.so then launch ogre some engine
use dlopen with LAZY flags (or the other don't remember) and thus fail to
properly figure out DRI, i think you are experiencing somethings along thus
line with ogre.

Don't worry for the path /usr/X11R6 is old path of non modular xorg, since
then (since xorg modular which i think is in use in your ubuntu distro) lib and
module are under /usr/lib.

best,
Jerome Glisse

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