-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Benjamin Herrenschmidt wrote:
> - Caching issues. On a lot of chipsets, AGP memory must be mapped > non-cacheable. This isn't trivial on all architectures and it's not > always feasible to do with userland buffers. That means that either the > cache must be flushed at the time of the mapping _and_ the buffer not > touched at all by the CPU until it's unmapped, or the map call must > change the userland mapping to the buffer to mark it uncached. The > problems of course starts popping up if this buffer happens to be shared > between multiple processes... also, that user memory will also be mapped > in the kernel as part of the kernel's linear mapping, which is > cacheable. Thus you'll end up with pages mapped both cacheable and > non-cacheable in different contexts. This is a good way to cause > checkstops with a number of CPUs (certainly with PowerPC and I think > also with amd's). (At this point, for those who didn't figure out yet > that AGP was just a piece of crap in the first place, welcome to the > real world) There must be some way to deal with all this sanely on PPC. Apple has a number of OpenGL extensions for making user memory directly accessable to the graphics engine. Perhaps their specs can provide some clues as to how they do it? http://oss.sgi.com/projects/ogl-sample/registry/APPLE/client_storage.txt http://oss.sgi.com/projects/ogl-sample/registry/APPLE/vertex_array_range.txt http://developer.apple.com/graphicsimaging/opengl/extensions/apple_texture_range.html -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.6 (GNU/Linux) iD8DBQFDwphDX1gOwKyEAw8RAlbbAJ9B42ZX+19keJ1tUo5hJa+43YouFgCfUIsl DV99Rz8I5HS9BXWWxOCyDWw= =fweg -----END PGP SIGNATURE----- ------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Do you grep through log files for problems? Stop! Download the new AJAX search engine that makes searching your log files as easy as surfing the web. DOWNLOAD SPLUNK! http://ads.osdn.com/?ad_id=7637&alloc_id=16865&op=click -- _______________________________________________ Dri-devel mailing list Dri-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/dri-devel
