Re: PCI DMA into USER space

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"Mayhall, Tony" wrote:
>
> Does anyone have an example (that works) of how to DMA from a PCI card into
> user space on a PC running Linux? We do this on Unix systems and need to be
> able to do this under Linux.

Have your driver use remap_page_range to make the DMA pages for your
card visible to the mmap() caller. Then have userspace mmap directly to
the DMA-able pages.

If you are really mean you want userspace to talk directly to MMIO
address space on a PCI card, then you use io_remap_page_range instead,
but otherwise the above procedure is the same.

For sample code, grep for remap_page_range in drivers/* of any recent
Linux kernel source tree.

        Jeff

-- 
Jeff Garzik              | Liberty is always dangerous, but
Building 1024            | it is the safest thing we have.
MandrakeSoft, Inc.       |      -- Harry Emerson Fosdick
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