Hi Arnd, Daniel, On Mon, Dec 12, 2011 at 10:18 PM, Arnd Bergmann <arnd@xxxxxxxx> wrote: > On Saturday 10 December 2011, Daniel Vetter wrote: >> If userspace (through some driver calls) >> tries to do stupid things, it'll just get garbage. See >> Message-ID: <CAKMK7uHeXYn-v_8cmpLNWsFY14KtmuRZy8YRKR5Xst2-2WdFSQ@xxxxxxxxxxxxxx> >> for my reasons why it think this is the right way to go forward. So in >> essence I'm really interested in the reasons why you want the kernel >> to enforce this (or I'm completely missing what's the contentious >> issue here). > > This has nothing to do with user space mappings. Whatever user space does, > you get garbage if you don't invalidate cache lines that were introduced > through speculative prefetching before you access cache lines that were > DMA'd from a device. I didn't see a consensus on whether dma_buf should enforce some form of serialization within the API - so atleast for v1 of dma-buf, I propose to 'not' impose a restriction, and we can tackle it (add new ops or enforce as design?) whenever we see the first need of it - will that be ok? [I am bending towards the thought that it is a problem to solve at a bigger platform than dma_buf.] > > Arnd Best regards, ~Sumit. > > -- _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
