On Sun, 2005-03-13 at 17:17 -0500, Jon Smirl wrote: > On Mon, 14 Mar 2005 08:52:46 +1100, Benjamin Herrenschmidt > <[EMAIL PROTECTED]> wrote: > > > > > The best model would be to chuck the AGP/PCI Express interface on the > > > board and have a hyperchannel instead. Hyperchannel provides full > > > cache consistency without all of these flushing problems. The GPU > > > really is another specialized CPU, give it a CPU class memory > > > interface. > > > > You mean HyperTransport ? Well, PCI Express isn't far from that > > neither... > > Yes, HyperTransport. That's what I get for writing email while the > babies are crying. > > Does PCI Express support a full cache coherency protocol like > HyperTransport?
Or just like PCI :) AGP is just a special case, and I'm not even sure wether the cache incoherency is a spec thing or just that all implementations are broken :) I'll check when I find my AGP spec. > So if the GPU touches a page of system memory, the > system memory will get flushed out of the CPU cache? In that case we > don't need to mark shared GPU/CPU memory as non-cachable. Well, that's what happen with a normal cache coherent setup, but I'm fairly sure that won't happen with AGP on a lot of machines. Ben. ------------------------------------------------------- SF email is sponsored by - The IT Product Guide Read honest & candid reviews on hundreds of IT Products from real users. Discover which products truly live up to the hype. Start reading now. http://ads.osdn.com/?ad_id=6595&alloc_id=14396&op=click -- _______________________________________________ Dri-devel mailing list Dri-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/dri-devel
