Messages in this thread | | | Subject | Re: [Linaro-mm-sig] Changing vma->vm_file in dma_buf_mmap() | From | Christian König <> | Date | Thu, 17 Sep 2020 14:03:48 +0200 |
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Am 17.09.20 um 13:31 schrieb Jason Gunthorpe: > On Thu, Sep 17, 2020 at 10:09:12AM +0200, Daniel Vetter wrote: > >> Yeah, but it doesn't work when forwarding from the drm chardev to the >> dma-buf on the importer side, since you'd need a ton of different >> address spaces. And you still rely on the core code picking up your >> pgoff mangling, which feels about as risky to me as the vma file >> pointer wrangling - if it's not consistently applied the reverse map >> is toast and unmap_mapping_range doesn't work correctly for our needs. > I would think the pgoff has to be translated at the same time the > vm->vm_file is changed? > > The owner of the dma_buf should have one virtual address space and FD, > all its dma bufs should be linked to it, and all pgoffs translated to > that space.
Yeah, that is exactly like amdgpu is doing it.
Going to document that somehow when I'm done with TTM cleanups.
Christian.
> > Jason > _______________________________________________ > Linaro-mm-sig mailing list > Linaro-mm-sig@lists.linaro.org > https://lists.linaro.org/mailman/listinfo/linaro-mm-sig
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