On Fri, 4 Jan 2013, Alex Deucher wrote:
R6xx and r7xx are really all you need to worry about in this case. R1xx-r5xx UMS uses a different kernel interface for command submission and evergreen and later don't have UMS drm support. UMS r6xx/r7xx support used the same kernel interface for command submission but the kernel side was much simpler.
OK, I have found an old machine with RV730 GPU and a known-working UMS: 2.6.35 kernel, 6.13.2 DDX, 7.8.2 mesa (classic), 1.9 Xorg). I changed the kernel to the latest drm-next and ran tests with and without my CS-refactoring patches. Here are the results:
* It appears that drm-next in its current state is broken with regard to UMS (nothing to do with my patches, it was pre-broken to begin with). UMS provokes the kernel into a NULL-pointer dereference oops. Good news is that I have tracked down the crash and I will be sending the patches with the fix shortly. * There are multiple patches that contributed to the breakage of UMS. I didn't bother pin-pointing them all, but one that I looked (6a7068b4) dates back to April 2012 so there are kernels out in distros that crash on UMS. That probably tells us how many UMS users are left out there :-). BTW, the reason UMS crashes is because parser->rdev is NULL in UMS mode so every patch that tries to dereference it (and shares the code path with UMS) will cause an oops (it will become clear when you see the patches). * So, having fixed the above incidental finding, I got my machine with ancient UMS-userspace and a shiny latest drm-next kernel (plus my CS-refactoring patches plus my yet-to-be-sent UMS fixes) to work. My test consists of bringing up Gnome (it's Gnome 2 on that machine), running glxgears, sphereworld (an example code from OpenGL Superbible book), and OpenArena. Everything seems to work. * Going back to KMS and retesting there, things still look good. So this (with tests I did on Friday) should cover all the cases.
Additionally, UMS requires the old non-gallium 3D drivers. It sounds like some other change in the ddx broke UMS support for r6xx/r7xx.
The DDX segfault I reported on Friday was provoked by trying to run Gallium 3D driver on the top of UMS. Once I switched back to classic, the crash went away. So I guess the userspace crash was provoked by some obscure path that was never intended to be exercised. I don't think
it's worth investigating further. -- Ilija _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
