On Tue, 2009-12-15 at 22:26 +0100, Gerhard Pircher wrote: > > Von: "Michel Dänzer" <mic...@daenzer.net>
> > On Tue, 2009-12-15 at 13:37 +0100, Gerhard Pircher wrote: > > > > Von: "Michel Dänzer" <mic...@daenzer.net> > > > > > > > guess there could be many possible causes for the problem, but the > > > > most likely seems some kind of coherency issue between the CPU > > > > writes and GPU reads. > > > Well, the northbridge doesn't guarantee coherence. So I'm sure you're > > > correct. Although I can only see the problem ATM, when the GPU writes > > > data to system memory, which is later read by the CPU. > > > > What exactly does 'can see' mean? > :) > Well, I didn't verify that this happens on my machine. But I'm sure it > is the case with memory allocated by the generic AGP layer functions (as > far as I can see they allocate cacheable memory), as the bridge's snoop > logic is buggy. As you say, it must be some sort of coherency issue. I don't think we've ever used cacheable memory with any AGP bridge in Linux. > > > I guess the memory used for this test is allocated by the AGP layer > > > and not by the radeon driver? > > > > No, it's allocated by radeon/TTM. > And this memory is mapped uncacheable by radeon/TTM? Yes. > Doesn't that limit the maximum usable memory for radeon/TTM to the > vmalloc space? That could only be relevant for kernel mappings. The kernel only maps buffer object (BO) memory when/while necessary, which usually isn't the case. -- Earthling Michel Dänzer | http://www.vmware.com Libre software enthusiast | Debian, X and DRI developer ------------------------------------------------------------------------------ This SF.Net email is sponsored by the Verizon Developer Community Take advantage of Verizon's best-in-class app development support A streamlined, 14 day to market process makes app distribution fast and easy Join now and get one step closer to millions of Verizon customers http://p.sf.net/sfu/verizon-dev2dev -- _______________________________________________ Dri-devel mailing list Dri-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/dri-devel
