about firefox ... / dont understand anything

Mike A. Harris mharris at mharris.ca
Thu Mar 16 06:54:51 UTC 2006

LarryT wrote:

>> A. Which graphics card are you using?
> ATI Radeon 7000 RV6DL 32mo
>> B. Which drivers for the graphics card are you using?
> Not sur to kown how to get this info :!
> going through system/admin/display :
> "ati - ATI Mach8, Mach32, Mach64 ad Rage XL card"
> Here is the pout put of xorg.conf :
> Section "Device"
>         Identifier  "Videocard0"
>         Driver      "ati"

The "ati" driver wrapper module is a problem which should be avoided.

Ideally, in the perfect world, you should be able to use the "ati"
wrapper module regardless of what ATI chip family and revision you
have, and it should automatically load the proper actual driver for
you, as all the "ati" module does, is scan your system and determine
what (if any) ATI hardware is present, PCI, AGP, ISA, etc., and if it
finds any, it looks up the device in a list which tells it which
"real" driver to use.  The "real" drivers are "atimisc", "r128", and
"radeon".  It then loads the proper driver, and unloads itself.

Or at least that is the intention of "ati".

Unfortunately, the real world doesn't quite line up with this ideal
situation very well, and there are often PCI IDs which have been added
to the "radeon" driver by one of the many upstream Radeon driver
developers, which were not added to the "ati" wrapper's detection
routines at the same time, resulting in the "ati" wrapper being
unaware of a given chip, when in fact the chip is supported by the
"radeon" driver.

The result is that the "ati" wrapper will be unable to detect some
hardware and reroute it to the "radeon" driver, but if you use the
"radeon" driver directly you avoid the middle man, and avoid that
problem path entirely.

As such, it is very highly recommended to _never_ use the "ati"
wrapper for Radeon hardware, as it is very highly likely to not
be in perfect sync with the actual current Radeon hardware
support.  There are other bugs/problems which have come up in
the "ati" wrapper over time as well, and while they get fixed
eventually, something else inevitably breaks.  It's just an extra
layer of code which can cause unnecessary grief over just using
the proper driver module to begin with:  radeon

If you use "radeon" as the driver, and your video card doesn't work,
don't even bother trying to use "ati", because as I stated above, all
"ati" does, is say "oh, you have a Radeon" and load the "radeon"
driver.  Instead, if the "radeon" driver does not work, file a bug
report in X.Org bugzilla and describe the problem in detail, and
attach your X server log and config file.

Currently, our video detection should detect all supported Radeon
hardware and automatically assign them to the "radeon" driver, all
Rage 128 hardware and automatically assign it to the "r128" driver,
and all Mach64, Rage, RageXL, and older hardware and assign it to
the "ati" wrapper (although I suppose in light of what I said
above, 'atimisc' might be more appropriate, but the problem case
with "ati" has been Radeon hardware, rather than Mach64, so it's
a moot point in practice).

On a final note, I should state that if you ask around, you will get
very different advice about this from some other people perhaps.  Some
people recommend using the "ati" wrapper for all hardware, and that
conflicts with what I am recommending.  People who suggest to use
the "ati" wrapper for all ATI hardware unfortunately have not had
the pleasure of maintaining XFree86 and X.Org X11 in 12 operating
system releases over a period of 5.5 years and discovering just how
unreliable the "ati" wrapper is in the real world.  My advice comes
from experience in action, rather than ideological best-case
wishful thinking of those who recommend the wrapper.  ;o)

Mike A. Harris  *  Open Source Advocate  *  http://mharris.ca
                       Proud Canadian.

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