Jeff Hartmann wrote: > > > About the Mesa backing store for textures, is there any reason why this > > memory cannot be mapped into AGP space? Admittedly, my knowledge of AGP > is > > very thin, but I always thought that you had some amount of virtual AGP > > address space that you could map to basically arbitrary physical pages... > > Well there are some issues with mapping the backing store into AGP. If we > ever need to directly access an image from the CPU we can't map the physical > pages into agp memory because every read access from the CPU will be > uncached. (Unless the host chipset has a special cached agp memory type, > which most do not have anything close to this functionality.)
You could also unmap in those circumstances. Fallbacks are slow & relatively rare. > Remember whenever you transition memory into agp space that has been cached > before, you must flush the cache's on all CPUs. (Can be very bad on SMP > systems, seems managable for single cpu systems, but less then ideal.) > Basically the rule is that if you need to ever read something again, don't > use agp memory (unless like stated before the card can do that for you.) Reading from textures (other than in fallbacks) is fairly rare & if it ever happens you can shut down the whole mechanism & keep all textures locally (so the bad thing only happens once). Keith _______________________________________________ Dri-devel mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/dri-devel
