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    SubjectRe: locking user memory and kiobuf
    Alan Cox wrote:
    >
    > > kiobuf sounds perfect for a problem we have. Currently I use mmap() to map
    > > pages from __get_free_pages() into user space for dma. This is not totally
    > > satisfactory, tho, in part because the resulting group of pages is not mapped
    > > contiguously into kernel.
    >
    > If you have a situation where that is hard to handle you can vmalloc a block
    > of memory then map that into user space. drivers/char/bttv.c does it. Its
    > ugly and bttv needs to switch to kiovecs in 2.3.x if I get time.

    On a tangent issue, is there an example somewhere of driver code storing
    and retrieving objects from VM? something along the lines of

    swap_in_and_lock_page(page);
    ptr = page_address(page);
    /* access ptr */
    unlock_pack(page); /* page can now be swapped out if necessary */

    --
    Jeff Garzik | Just once, I wish we would encounter
    Building 1024 | an alien menace that wasn't immune to
    MandrakeSoft, Inc. | bullets. -- The Brigadier, "Dr. Who"

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