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    SubjectRe: Enabling peer to peer device transactions for PCIe devices


    On 05/12/16 12:14 PM, Jason Gunthorpe wrote:
    > But CMB sounds much more like the GPU case where there is a
    > specialized allocator handing out the BAR to consumers, so I'm not
    > sure a general purpose chardev makes a lot of sense?

    I don't think it will ever need to be as complicated as the GPU case.
    There will probably only ever be a relatively small amount of memory
    behind the CMB and really the only users are those doing P2P work. Thus
    the specialized allocator could be pretty simple and I expect it would
    be fine to just return -ENOMEM if there is not enough memory.

    Also, if it was implemented this way, if there was a need to make the
    allocator more complicated it could easily be added later as the
    userspace interface is just mmap to obtain a buffer.

    Logan

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