EXA pixmap alignments.

Felix Kühling fxkuehl at gmx.de
Wed Sep 28 06:18:39 PDT 2005

Am Mittwoch, den 28.09.2005, 18:59 +1000 schrieb Benjamin Herrenschmidt:
> On Wed, 2005-09-28 at 08:32 +0200, Lars Knoll wrote:
> > Yes, that's what I currently do on nv. I also have an idea how to do 
> > fb->system using PCI scatter/gather, but didn't have the time to try it out 
> > up to now.
> You may want to "peek" my kernel side code for that once I'm finished...
> I hope I'll have something to play with sometimes next week-end.
> > Btw, is there any way to know if an AGP chipset supports writes 
> > from card to AGP?
> Not really afaik. The radeon DRI does a sneaky test at startup, it
> "tries" to do a writeback to a scratch location and verifies if it
> actually worked. If not, it uses MMIO reads to read the scratch value
> (used for register aging afaik), if yes, it reads the one that was
> written to AGP. That's the only thing that info is used for though at
> the moment.

That test used to be unreliable on my old Radeon 7500. The test would
pass and the AGP writeback would fail later on after a few seconds of
3D. I had to work around that problem by reducing AGP speed from 4x to



| Felix Kühling <fxkuehl at gmx.de>                     http://fxk.de.vu |
| PGP Fingerprint: 6A3C 9566 5B30 DDED 73C3  B152 151C 5CC1 D888 E595 |

More information about the xorg mailing list