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    SubjectRe: can device drivers return non-ram via vm_ops->nopage?
    On Sun, Mar 21, 2004 at 06:23:22AM +0000, Christoph Hellwig wrote:

    > Not sure how you get to fetchop here, but that driver does map ram
    > pages so it should take pagefaults and not use remap_page_range().

    It's been a while since I looked at this.... the fetchop driver maps
    AMO space which is excluded from the EFI memory map (and any SHub
    aliases) and thus shouldn't be touching anything normally considered
    RAM.

    <pause>

    Checking the source I see:

    if (remap_page_range(vm_start, __pa(maddr), PAGE_SIZE, vma->vm_page_prot)) {
    fetchop_free_pages(vma->vm_private_data);
    vfree(vdata);
    fetchop_update_stats(-1, -pages);
    return -EAGAIN;
    }

    as part of the drivers 'mmap fop'. The underlying page is actually
    from region-6 so I'm pretty sure it's safe. If you think it is doing
    something weird please let me know.



    --cw
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