On Mon, 2009-12-14 at 23:21 +0100, Gerhard Pircher wrote: > > Next I booted the kernel with radeon.test=1 and this test fails > immediately with a message like this: > > [drm:radeon_test_moves] *ERROR* Incorrect GTT->VRAM copy 0: Got 0xf14a88f0, > expected 0xf14a6680 (GTT map 0xf14a6000-0xf15a6000) > > A different aperture size doesn't make any difference. However the test > works in PCIGART mode. > Now I wonder what the problem could be, as I don't have a clue about > the radeon/DRM code. Can somebody explain me, how the test works and > what the error message means for the AGPGART driver?
The test output is a little cryptic and could be improved... The failing phase of the test fills the GTT memory with the kernel virtual addresses of itself, copies it to VRAM with the GPU, reads it back again with the CPU and verifies the contents. It read back 0xf14a88f0 when it expected 0xf14a6680, so the latter is the kernel virtual address of the first word which wasn't copied correctly. Subtracting the start of the GTT map (0xf14a6000) yields that only 1664 bytes (+ 2, as the first two bytes of the incorrect word are correct) were copied correctly. The normal ring and IB tests are probably too simple to catch that kind of problem. I don't suppose higher transfer rates work any better? :) I 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. Hope this helps, -- Earthling Michel Dänzer | http://www.vmware.com Libre software enthusiast | Debian, X and DRI developer ------------------------------------------------------------------------------ Return on Information: Google Enterprise Search pays you back Get the facts. http://p.sf.net/sfu/google-dev2dev -- _______________________________________________ Dri-devel mailing list Dri-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/dri-devel
