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    SubjectRe: Question: how to copy to user space from a tasklet
    Tom Brown wrote:
    > Thanks, think I'm there:
    >
    > 1 - The user calls mmap() with a specific offset to flag that he wants a
    > DMA buffer
    >
    > 2 - I then 'vmalloc' the buffer, and call 'setPageReserved' for each page
    >
    > I then step over each page, and:
    >
    > 3 - call 'vmalloc_to_pfn' to get a PFN for each page, and then
    >
    > 4 - call 'remap_page_range' for that page (I instead call
    > 'remap_pfn_range' for kernels >= 2.6.10, but I'm on 2.6.9)
    >
    > This gives me the buffer, and the interrupt handler then just uses
    > 'memcpy' to copy data to the user.

    I would have thought of a bunch of alloc_page() and vm_insert_page() but I
    don't know if vm_insert_page exists in 2.6.9 and if it honors user limits.

    Plus dma_map_page() to get zero-copy operation with a DMA capable device.
    --
    Stefan Richter
    -=====-==-=- =-=- =--=-
    http://arcgraph.de/sr/


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