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    SubjectRe: mmap hw behavior
    David Miller wrote:
    > From: Michal Simek <michal.simek@petalogix.com>
    > Date: Wed, 08 Jul 2009 20:03:27 +0200
    >
    >
    >> David Miller wrote:
    >>
    >>> From: Michal Simek <michal.simek@petalogix.com>
    >>> Date: Wed, 08 Jul 2009 19:03:11 +0200
    >>>
    >>>
    >>>
    >>>> When I call mmap for that open file with pointer to calloc place
    >>>> (first parameter, + length zero) it should be one tlb invalidation
    >>>> for calloc and new tlb which connect open file. We check it and we
    >>>> don't have any tlb invalidation that's why I think that kernel do
    >>>> different thigs. Or is it there any copying? Or anything different?
    >>>>
    >>>>
    >>> There is no need to tlb flush the calloc area unless that memory area
    >>> is actually touched by the user application and thus the page is
    >>> faulted in.
    >>>
    >>>
    >> That calloc area is filled by any value (in that test). Is it mean that
    >> for this case when calloc area is touched
    >> there must be tlb invalidation + remapping?
    >>
    >
    > Yes, if the calloc area is written to by the application, there
    > should be a tlb flush when the mmap() overrides that virtual region
    > with a different mapping.
    >
    Can you please point me to any code which exactly do this? (for example
    file mm/mmap.c line from ... to ... )

    Thanks,
    Michal

    --
    Michal Simek, Ing. (M.Eng)
    PetaLogix - Linux Solutions for a Reconfigurable World
    w: www.petalogix.com p: +61-7-30090663,+42-0-721842854 f: +61-7-30090663



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