Athlon XP requires Option "NvAGP" "1"

[perryd]

To avoid system instability caused by a conflict between the speculative cache that the AMD XP processor is using and the memory use of AGPGART, AMD Athlon XP systems should include

Option "NvAGP" "1"

in the device section for their graphics card in XF86Config-4. This will allow the nvidia AGP driver to be used in place of AGPGART (assuming that AGPGART is being loaded as a module).

My system used to lock up occasionally while doing intense opengl grapics (especially in FlightGear or in some screen savers). I made this change yesterday and have had it running with either FlightGear or very complex screen savers since that change, and it has been completely stable.

The following link is to an article that explains in detail what the issue is.
http://www.linuxjournal.com/modules/NS-articles/lighter/6148s1.php

Good luck!
-Dave

[bwkaz]

Well it doesn't require it.

I've got an Athlon XP 1800, GF4 4200, in AGP mode, with the agpgart module doing the AGP work, and I haven't seen lockups when running any OpenGL or other graphics-oriented threads. This includes a couple of hours of playing UT2k3 at a time, a whole bunch of zsnes goodness, and a lot of Descent 3. Even X, which under 2.4.18 had intermitent issues with lockups, is fine.

I'm running 2.4.19, perhaps AMD's patch was incorporated into it? If that was the case, then either form of AGP handling should work fine...

[AlgUSF]

The AMD patch, is that when linux disables advanced speculative caching? If so, what kinda performance hit do you take when it disables it?