On Iau, 2004-10-07 at 15:40, Ville SyrjÃlà wrote: > Why can't we make AGP memory cached? Wouldn't it be enought to flush the > caches at some critical points?
Possibly although it is not trivial to see how we get that right, especially with the 4Mb kernel maps. The x86 processor cannot handle a page being mapped both cached and uncached at once. Even more excitingly this includes implicit suprise caching by the CPU (speculative and hardware prefetch). This is more a TLB than cache issue. > I was playing around with DirectFB and AGP some years ago and enabling > write-back caching didn't seem to have any side effects. Without caching > AGP is almost as bad as video memory for sw fallbacks. It would be nice to get cacheable AGP but that means some fairly hairy things especially on SMP systems. Pulling a page out of AGP doing a TLB shootdown for it, and then putting it back after wbinvd might work. One to talk to the processor people about. ------------------------------------------------------- This SF.net email is sponsored by: IT Product Guide on ITManagersJournal Use IT products in your business? Tell us what you think of them. Give us Your Opinions, Get Free ThinkGeek Gift Certificates! Click to find out more http://productguide.itmanagersjournal.com/guidepromo.tmpl -- _______________________________________________ Dri-devel mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/dri-devel
