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    SubjectRe: [PATCH v2 00/25] AMDKFD kernel driver
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    On Tue, Jul 22, 2014 at 11:21 AM, Daniel Vetter <daniel.vetter@ffwll.ch> wrote:
    > On Tue, Jul 22, 2014 at 10:19 AM, Oded Gabbay <oded.gabbay@amd.com> wrote:
    >>> Exactly, just prevent userspace from submitting more. And if you have
    >>> misbehaving userspace that submits too much, reset the gpu and tell it
    >>> that you're sorry but won't schedule any more work.
    >>
    >> I'm not sure how you intend to know if a userspace misbehaves or not. Can
    >> you elaborate ?
    >
    > Well that's mostly policy, currently in i915 we only have a check for
    > hangs, and if userspace hangs a bit too often then we stop it. I guess
    > you can do that with the queue unmapping you've describe in reply to
    > Jerome's mail.

    Not just graphics, and especially not just graphics from amd. My
    experience is that soc designers are _really_ good at stitching
    randoms stuff together. So you need to deal with non-radeon drivers
    very likely, too.

    Also the real problem isn't really the memory sharing - we have
    dma-buf already and could add a special mmap flag to make sure it will
    work with svm/iommuv2. The problem is synchronization (either with the
    new struct fence stuff from Maarten or with android syncpoints or
    something like that). And for that to be possible you need to go
    through the kernel.
    -Daniel
    --
    Daniel Vetter
    Software Engineer, Intel Corporation
    +41 (0) 79 365 57 48 - http://blog.ffwll.ch


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