[CentOS] Re: hardware acceleration with radeon -- R100 (7500) != R[V]250[SE] (9000/9000SE)

Sat Jul 9 21:46:51 UTC 2005
Bryan J. Smith <b.j.smith at ieee.org>

On Sat, 2005-07-09 at 16:25 -0500, Aleksandar Milivojevic wrote:
> I have different, much older Radeon.

The R100 (Radeon 7500) and R200 (Radeon 8500) had the most
specifications released.  From my understanding (was it Alan Cox who
told me?), it was the Weather Channel (or NOAA?) that paid Precision
Insight to work on the original R100 (Radeon 7500) and, with a little
less focus, the R200 (Radeon 8500) DRI driver.  The latter R2xx products
(especially the "Value" RV2xx like the 9100/9200) have varying support,
although the R250 (Radeon 9000) is supposedly one of the better ones
(not totally sure about the RV250 Radeon 9000SE, probably same as other
RV2xx cards).

For those that don't know, ATI has withheld the 3D specs on the R3xx
series (Radeon 9500+), although reverse engineering based on the R2xx is
slow moving.  I suspect the gap between "current" (proprietary-only) and
"legacy" (DRI option) will continue, much like it did after nVidia
released its specifications, and even code for XFree 3.3.x, on the NV0x
(TNT2/GeForce) before certain IP holders too issue (e.g., Intel,
Microsoft, others) and closed up.

Ironically, because ATI has more advanced 2D/motion capabilities in
their GPU, they have horded those specifications far more than nVidia,
who uses more standard/glued 2D/motion (although some of the GeForce 4
and 6000 series 2D/motion specs are available).

> Seems that support for some Radeon cards isn't stable with current
> kernels.

And people wonder why nVidia produces its own kernel module**, even
though the reality is that a binary XFree4/Xorg driver doesn't need
it and various kernel interfaces can be used.  A lot of it has to do
with the reality that there are many good reasons for this -- at least
when the kernel interfaces don't change (which has happened a few
times ;-).

[ **NOTE:  nVidia has opened up the GART (which was largely due to
several IP issues, some of Intel's on AGP namely) and now uses the
kernel's GART by default. ]

> If not add it.  Mine looks something like this (you'll have at least 
> BoardName line different, and my best guess without checking docs is 
> that 9000 uses same driver as 7500, if not Driver line will be different 
> too):
> Section "Device"
>          Identifier  "Videocard0"
>          Driver      "radeon"
>          VendorName  "Videocard vendor"
>          BoardName   "ATI Radeon 7500"
>          Option      "DRI"
> EndSection

Now hold on!  You're using a _true_ R100 (Radeon 7500) which probably
has the _best_ support.  From my understanding, that was the "primary
deliverable."  Everything from there has been an adaptation.

The R200 (Radeon 8500+) cards _are_ very different than R100 (Radeon
7500+) cards from a 3D standpoint (even if the 2D driver is the same
"radeon").  The R250 (Radeon 9000) and RV250 (Radeon 9000SE) are even
more different.


-- 
Bryan J. Smith                                     b.j.smith at ieee.org 
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