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    SubjectRe: mmap RAM?
    From said:
    > I am trying to write a driver for a new device. It is an MPEG2 video
    > *encoder*. The device sits on a PCI bus. It wants to DMA encoded
    > video to the host RAM.

    It works a page at a time because the kernel does lazy mapping, and anyhow
    may choose to forget random pages at random times. You also need to go
    through some of the other hoops to keep module reference counts correct.
    Take a look at the example at the above ftp site.

    Also, note that you cannot either the device must scatter-gather, or
    you use something like bigphysarea to get large contiguous buffers.
    Steve Williams "The woods are lovely, dark and deep. But I have promises to keep, and lines to code before I sleep, And lines to code before I sleep."

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      Last update: 2005-03-22 13:41    [W:0.018 / U:9.364 seconds]
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