Re: DRM memory manager on cards with hardware contexts

[Thomas Hellström]

Benjamin Herrenschmidt wrote: On Tue, 2006-09-19 at 11:27 +0200, Thomas Hellström wrote: But this should be the same problem encountered by the agpgart driver? x86 and x86-64 calls change_page_attr() to take care of this. On powerpc it is simply a noop. (<asm/agp.h>) Possibly. We sort-of ignore the issue for now on PowerPC and happen to be lucky most of the time because 32 bits PowerPC aren't that agressive at prefetching... I haven't looked at change_page_attr() implementation on x86 but I know they also map the linear mapping with large pages. I don't know what happens if you start trying to change a single page attribute. x86 can breakup that large page into 4k pages, so maybe that's what happens. Yes, I think that's what happens. I know some Athlon chips had a big issue with this some time ago. I notice there are special functions in <agp.h> to alloc / free GATT pages, so the general idea might be to have a pool of uncached pages in the future for powerpc? Even better would perhaps be to have pages that aren't mapped for the kernel. (like highmem pages on x86). /Thomas

-------------------------------------------------------------------------
Take Surveys. Earn Cash. Influence the Future of IT
Join SourceForge.net's Techsay panel and you'll get the chance to share your
opinions on IT & business topics through brief surveys -- and earn cash
http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV
--
_______________________________________________
Dri-devel mailing list
Dri-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/dri-devel