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    SubjectRe: More info for DSM w/r/t sunffb on 2.6.15-rc6
    From: Linus Torvalds <>
    Date: Fri, 23 Dec 2005 12:53:16 -0800 (PST)

    > So it may be that the insane sparc remap_pfn_range() users need to set the
    > dirty/accessed bits in the page protection flags by hand before to avoid
    > that. David?

    I'm pretty sure we set the dirty accessed bits at mapping time, so
    that shouldn't be an issue.

    But I wonder whether any of this is necessary at all.

    I did some digging to see how far back the "fall back to MAP_SHARED
    if MAP_PRIVATE fails" logic is in the X11R6 tree.

    I went back as far as I could in the XORG and XFree86 CVS for
    that SBUS support code, and the fallback to MAP_SHARED code has
    always been there.

    So I think something as simple as returning -EINVAL in the SBUS
    framebuffer mmap() driver if VM_SHARED is not set would be sufficient
    to deal with this.

    Something like this patch below.

    Signed-off-by: David S. Miller <>

    diff --git a/drivers/video/sbuslib.c b/drivers/video/sbuslib.c
    index 646c43f..ac937da 100644
    --- a/drivers/video/sbuslib.c
    +++ b/drivers/video/sbuslib.c
    @@ -46,6 +46,9 @@ int sbusfb_mmap_helper(struct sbus_mmap_
    unsigned long off;
    int i;

    + if (!(vma->vm_flags & VM_SHARED))
    + return -EINVAL;
    size = vma->vm_end - vma->vm_start;
    if (vma->vm_pgoff > (~0UL >> PAGE_SHIFT))
    return -EINVAL;
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      Last update: 2005-12-24 00:51    [W:0.020 / U:3.540 seconds]
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