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Attention: Proprietary video driver users (ATI, Nvidia, etc.)



There have been a number of bugs reported in Red Hat bugzilla against
X which have recently been tracked down to 3rd party video drivers being
the culprit behind the problem the user was experienced.  In many of the
cases however, it wasn't obvious that the 3rd party drivers were at
fault because the user was actually using the Red Hat supplied drivers,
and not using the 3rd party driver that they had previously installed.

Since I've wasted at least 6-8 hours in the last month diagnosing issues
of this nature which have later turned out to be caused by proprietary
drivers having been "installed" on the system, wether they were actually
being *used* or not, I thought I should write a short useful
informational email on the topic to the lists to try and inform people
of some pitfalls you may encounter if you even _install_ 3rd party
video drivers.

Both ATI and Nvidia, and perhaps even other 3rd party drivers out there
come in some form of tarball or equivalent form from the particular
vendor.  Most users seem to favour the hardware vendor supplied drivers
directly, rather than using more sanely packaged 3rd party packages that
contain the same drivers.  This is very unfortunate, because installing
these 3rd party tarball driver installations is very harmful to your
clean OS installation.

Both ATI and Nvidia's proprietary video driver installation utilities
replace the Red Hat supplied libGL library with their own libGL.
Nvidia's driver installs a replacement libglx.a X server module,
removing the Red Hat supplied X.Org module in the process.  ATI's
driver may or may not replace libglx.a with it's own, I haven't checked
(but if someone could confirm that, I'd appreciate knowing for certain).

Once you have either of these drivers installed on your system, you
can no longer use DRI with any video card.  So if you install the
ATI fglrx driver, while you should still be able in theory at least
to use the Red Hat supplied radeon driver, you may no longer be able
to use DRI with the radeon driver, because ATI's driver has blown away
critical files that come with the OS that are needed for proper
operation.

If you install Nvidia's driver, and later decide to install an ATI
card, and still have Nvidia's driver installed, bang - you will not
be able to get Red Hat supplied DRI 3D acceleration to work.  You must
remove Nvidia's driver completely from your hard disk, and completely
reinstall all of the xorg-x11 and mesa packages, and ensure they are
all intact by using:

rpm -Va

Another problem being reported by a few people, is they are unable to
get DRI to work because mesa libGL is looking for the DRI drivers in
the wrong directory.  The claim is that mesa is looking for the DRI
drivers in /usr/X11R6/lib/modules.

On a fresh OS install however, my findings are that mesa's libGL very
much is not looking in /usr/X11R6 for it's modules.  It is looking in
the proper location of /usr/lib/dri for the modules.  Why then is it
looking in the wrong place on some systems?

Answer:  Because of fglrx having been installed.  If you have had a
previous OS release installed, and have installed ATI's fglrx driver
from tarball, it has removed the OS supplied libGL et al and made
backup copies of them aparently.  Now you do an OS upgrade which works
properly and installs everything in the right place.  Then you uninstall
ATI's fglrx with whatever script or whatever they supply, and now you
try to run X, and get no DRI!

Well, since you don't have fglrx installed at all, it must be our
OS at fault right!  Wrong.  the uninstall script has put the OLD
libGL it backed up (from FC4 or whatever) back in the system,
overwriting the new FC5 supplied libGL in the process, and since
ATI's fglrx driver is DRI based as well, it looks for the DRI
modules in the wrong place now.

Conclusions:
If you are going to use any 3rd party proprietary drivers, please do
yourself and everyone else a huge favour, and at least get your
drivers from reputable 3rd party rpm package repositories such as
livna.org which packages both the nvidia and ati proprietary drivers
in rpm packages which install the drivers sanely without overwriting
Red Hat/Fedora supplied files.  These 3rd party packages install
the files in alternative locations, and configure the X server et al.
appropriately so that everything works.  Since they do not blow
away OS supplied files, you can use the OS supplied drivers still
by reconfiguring xorg.conf.  Also, if you decide to uninstall the
3rd party drivers via rpm, they just go away and cause no further
harm to the system.  So PLEASE USE THIRD PARTY RPM PACKAGES if you
_must_ use 3rd party drivers.  It helps create world peace.

If you choose to install ATI or Nvidia tarball/whatever drivers
directly from ATI/Nvidia (or any other vendor for that matter), your
system is 100% completely and totally unsupported.  Even if you are
using _our_ drivers, your 3rd party driver installation may have
blown away our libGL, our libglx.a or any other files that have been
supplied by our OS.  As such, your system is not supported.

For those who encounter a bug of any kind whatsoever while using
3rd party video drivers, completely remove the 3rd party drivers
from your system, and then perform a full "yum update" to ensure
you have the latest Fedora Core supplied X packages installed.  After
doing this, do an "rpm -Va" of your whole system, in particular the
xorg-x11-*, mesa-* and lib* packages.  If there are any discrepancies
found in any of the Fedora supplied packages, in particular in libGL,
or the X server packages, remove them and reinstall them and reverify
that the files installed on your system are the ones shipped by
Fedora.

If you are able to reproduce the problem you are having after having
performed these steps, and having ensured that you are neither using
3rd party drivers, nor even have them installed, then feel free to
file a bug report in bugzilla.

By doing this small amount of pre-diagnosis of your own system if
you are using 3rd party drivers, you will save yourself a lot of
headaches, and will save other people, including developers such
as myself from wasting endless hours trying to diagnose problems
which turn out to be bogus.  Hours which could have been spent
fixing legitimate bugs that are present in bugzilla.

As an additional note - if anyone is using proprietary drivers and
has any problems which they believe might actually be a bug in
Xorg and not in their proprietary driver - file such bugs directly
in X.Org bugzilla.  X.Org has an nVidia (closed) component specifically
for the proprietary driver, and Nvidia engineers get those bugs and
will investigate them over time.

Anyhow, I hope this helps people understand at least some of the
problems that can occur when you opt to using 3rd party drivers,
present some alternatives, and to help people diagnose their own
problems which might be caused by having installed 3rd party
drivers.

Thanks for reading.
TTYL


P.S. Feel free to forward this email on to any other lists or
people whom you think might benefit from it.  Also, if anyone thinks
this information would be useful to have on the Fedora Wiki or
somewhere else, feel free to copy my email into a wiki page, or
paraphrase, etc.



--
Mike A. Harris,
Systems Engineer, X11 Development team,
Red Hat Canada, Ltd.


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