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    SubjectRE: [ofa-general] Re: Demand paging for memory regions
    On Tue, 12 Feb 2008, Felix Marti wrote:

    > > I don't know anything about the T3 internals, but it's not clear that
    > > you could do this without a new chip design in general. Lot's of RDMA
    > > devices were designed expecting that when a packet arrives, the HW can
    > > look up the bus address for a given memory region/offset and place the
    > > packet immediately. It seems like a major change to be able to
    > > generate a "page fault" interrupt when a page isn't present, or even
    > > just wait to scatter some data until the host finishes updating page
    > > tables when the HW needs the translation.
    >
    > That is correct, not a change we can make for T3. We could, in theory,
    > deal with changing mappings though. The change would need to be
    > synchronized though: the VM would need to tell us which mapping were
    > about to change and the driver would then need to disable DMA to/from
    > it, do the change and resume DMA.

    Right. That is the intend of the patchset.


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