On Sat, Apr 19, 2014 at 5:54 AM, Christian König <deathsimple@xxxxxxxxxxx> wrote: > Hi Marek, > > I've noticed this before as well, and I agree that it looks like a memory > corruption. Not sure if the async DMA on the GPU or the CPU is overwriting > something because of a race condition or something like this. > > Anyway, can you come up with a simple test case to reproduce the issue? For > me it occurred only randomly while working on UVD support for R7xx. If you > have something more reliable I could dig into it with my RV710. > Double check the code in the kernel that copies the IB from the user copy to the kernel copy. We had a bug when we first merged DMA support where we weren't properly copying the across the IBs. There may still be a case where this is an issue: http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=de0babd60d8d43b58fd06a7803151d32cb589af0 Alex > Christian. > > Am 19.04.2014 01:48, schrieb Marek Olšák: > >> Hi, >> >> If you submit a lot of graphics and DMA IBs interleaved, the graphics >> CS checker sometimes fails with this message: >> >> [ 3846.435661] Forbidden register 0x0014 in cs at 9 >> [ 3846.435664] [drm:radeon_cs_ib_chunk] *ERROR* Invalid command stream ! >> >> This error is only used for type-0 packets, but we don't use these >> packets on R700 at all. Somehow, the graphics CS checker received >> either the DMA IB or random garbage. My guess is there is memory >> corruption happening during IB uploading and/or IB checking in the >> kernel. Also, if you are unlucky, the GPU hangs instead. >> >> The CS thread offloading was disabled in Mesa, so the user space was >> single-threaded. >> >> There are 2 ways to fix this: >> - disable async DMA in Mesa >> - call usleep(1) after the RADEON_CS ioctl returns >> >> This is just a heads-up. In the worst case, we can disable async DMA >> for R700 in Mesa. >> >> Marek >> _______________________________________________ >> dri-devel mailing list >> dri-devel@xxxxxxxxxxxxxxxxxxxxx >> http://lists.freedesktop.org/mailman/listinfo/dri-devel > > > _______________________________________________ > dri-devel mailing list > dri-devel@xxxxxxxxxxxxxxxxxxxxx > http://lists.freedesktop.org/mailman/listinfo/dri-devel _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
